Bike Advise
Content
Tuning the Carb for Perfomance and mileage
Dear Biker,
• • • • • • •
Are you tired of cold starts? Need to raise the throttle everyday to get the cold engine running? Does someone have the same bike as yours and are you tired of losing to him in drag races? Suddenly, the fuel efficiency has reduced after a service? Has the mechanic has screwed up your tuning? Engine gives hiccups when you open the throttle? Or your bike is just missing that smooth acceleration whenever you want? Or your engine overheats even if you did not race too much.
May be the following will help you in tuning your mean machine for optimal power delivery and best fuel economy. This guide aims at tuning the fuel/air screw to give you an optimal air-fuel mixture. An optimal mixture gets maximum performance from your machine.
This Guide Applies To
All the single cylinder bikes, 2 stroke or 4 stroke having a carburetor. Tachometer is very handy and a must for a newbie or the tuning process will be very slow or painful or imperfect. Disclaimer: Though whatever I have written here wont do any damage to your machine, finally you must not blame me for whatever happens. I am here to help if anything goes wrong.
Getting Things In Action
Turn the idle settings screw so that rpm reaches about 3000 rpm. Now tune the air/fuel screw to make the mixture leanest as possible. Please refer to the above whether you must turn the screw clockwise or anti clockwise. As you make the mixture leaner, slowly the engine RPM decreases… Go on doing this until you have put the fuel screw to the leanest possible point. At the same time, ensure that the engine does not stall, by turning the idle-screw. Tough huh? You’ll get used to it OK the engine is running and the mixture is lean. If you notice from the engine sound OR if you see the tachometer, the engine RPM will not be steady at this point. Now very slowly start turning the fuel screw anti-clockwise, quarter to 1/8th turn at a time. You will notice that the RPM increases slowly and steadily. Again, do this very very slowly. Also count the total number of turns as you wind out the screw. You’ll notice that when you have turned it to about 3-4 full revolutions, the engine RPM slowly becomes constant. It is this point that you must stop screwing more. This probably is the optimal setting for your engine. Further on, try turning the screw even more and more to 5-7 revolutions and you’ll notice that the engine RPM will slowly decrease. When this happens, you are just putting in a too rich mixture in your engine. At this point the engine loses all the fuel efficiency and the mixture is not optimal. Repeat the process about 2-3 times. Count the revolutions each time and get the setting which you feel is correct. OK the engine is humming perfectly, now what? Decrease the idle setting screw to about 1000rpm in the tachometer. When the engine slows down, just twist the throttle. The response should be crisp and quick. It should not give any hiccups! Try shutting off the engine and restarting. The engine MUST start in a single kick or self with out giving throttle. If this happens, the setting is ok. Now get a ride and you’ll notice the difference for good or bad
You’ll immediately notice change in the engine sound and the throttle response. Your engine can become more smooth or harsh. Another important point is, Ride and Feel. Always take a ride and get the feel of the bike in each gears, check the response and the engine sound. You’ll quickly come to know once you get the feel of the bike that you want to make the mixture rich or lean. It may take a few iterations before you fix a setting as permanent. Try calculating the mileage per liter and tally it with your setting and the feeling you get. Troubleshooting Here are some symptoms and their quick solutions:
• • • • •
•
Engine dies while tuning. Try the process all over again. This time set the idle screw higher/faster. Engine gives hiccups while driving, specially while in higher gears. May be the mixture is too lean. Try again. Engine heats up. The mixture is too lean or too rich. Try again. Whenever I race up the engine, the rpm increases fast but very slowly comes down to idle. The mixture is not optimal, probably towards leaner side. Try again. Too much low end torque and the engine sound is very beaty/thumpy. You’ll face a low mileage surely, when you drive below 40kmphr. You have tuned on the higher/richer side. I have doubts or I have other problems. Why don’t you put in a comment?
How ti fit K&N filtetr and Rejet This post is for all my fellow bike riders who wish to extract the last possible juice out of your ride. This post is regarding to the fitting of free flow air filters, its effects and how to rectify it using the method of rejetting. You need to consider re-jetting your bike whenever there’s been a major change to the air intakes (like installing K&N filters which allow more air to pass to the carburetor), or adding drag pipes. Both modifications will lean out the air-fuel mix. The stock jet can only allow a certain amount of fuel to pass through and is designed according to the specification of the vehicle. Installing larger jets increases fuel to the carburetor to restore the 14 parts air to 1 part fuel optimum mix. This mixture is called stoichiometric ratio. Whenever the amount of air intake is increased, the fuel part is also to be increased. In all other cases, the stock jets will take you through 95% of your riding requirements.
Since the main jet effects all speed ranges after idle, you need to get the main jets right first, and then tune the mid-range and low end. All tuning should be done on a fully warmed up engine because that’s the way you usually ride; the spark plugs should have been previously checked and cleaned; the gas tank should be at least half full; a new or recently installed fuel filter if present; the air intake filters checked for holes, and cleaned; and all air intake and manifold connections tight and secure; the battery fully charged; and the carburetors synchronized, if it’s a multiple cylinder engine (more than one cylinder, eg: kinetic comet ) for optimum results. We are now going to tune the carburetor without the help of a tachometer (engine speed). High speed or top end main jet sizes are determined by full open throttle performance. Low and mid-range tuning is determined mainly by how the bike feels to you as you roll the throttle. Mikuni CV carburetor is different from the Keihin CV. So is the difference with other carburetors. So tuning will be different in different vehicles.
Note: If you do sense a loss of power, or rough running on a stock vehicle, it may due to some other reason. In this case re-jetting is not the solution to the current problem. Please take the bike to an authorized mechanic and rectify the problem. HIGH SPEED JETTING High speed performance (80 KPH and up) is controlled by the main jets. To make sure you have the right main jets, take your bike out to an open highway where you can safely (and legally) open the throttle all the way in top gear. Ride the bike full open and let the bike get to top speed. Again, do this only if you are experienced and comfortable running at top speed and you are not in danger of injuring yourself or someone else. A. If at top speed or before, the bike runs rough, heavy throttle feel or begins to hesitant and buck, your main jet is TOO BIG. The mix is too rich (more fuel than the optimum 1 part fuel to 14 parts air) and you are getting an uneven burn and poor performance. Install smaller main jets and take the bike for another test run. Another way to determine rich mixture is, when u cold start the vehicle and if the bike starts in the very first crank the mixture is rich (no need to use the choke in this instance). Low fuel efficiency and more smoke in the exhaust than usual are some of the characteristics of a rich mixture. B. If before top speed the engine is running smooth, but has no power, seems to be running hot or knocking from the engine and you can’t push the bike to top speed, then your main jets are too SMALL. You are running too LEAN a mix (less fuel than the optimum 1 part fuel to 14 parts air) for maximum engine performance. Put in LARGER main jets and take the bike out for another test run. Another way to determine lean mixture is the difficulty u feel when cold starting. Even after repeated cranking, if the engine does not start, the mixture is lean. When u closes the throttle in a downhill, if u hears popping or cracking sound from the exhaust, it is again due to the lean mixture.
MID-RANGE OR MID-SPEED TUNING The carburetor needle controls mid-range performance. The needle tapers down to a point that fits into the main jet. The needle is lifted upward (along with the slide) by the carburetor diaphragm as the air flow increases through the carburetor. As the needle moves upward it is withdrawn from the main jet, allowing more fuel to mix with the increased air volume. All that is needed to modify mid-range performance is to place (or remove) one or more small, thin washers between the diaphragm and the head of the carburetor needle where it’s held in the diaphragm. Adding washers effectively raises the tapered needle further out of the main jet at all engine rpm’s and allows more fuel to mix with air to create a richer mix. Removing a washer effectively leans out the air-fuel mix. There’s usually no need to replace the stock needles since they have proven over time to provide good performance and good gas mileage. If you do use a third party needle for increased performance, then anticipate lower fuel efficiency. Mid-range tuning is accomplished mainly by how the bike performance feels to you. If there’s a smooth increase in power as you roll the throttle, then you’re there. If there’s a slow response or there’s no power, then the mix may be too LEAN and you may need to add one or more washers to richen the mix. If the bike accelerate with power, but feels rough, you may be too RICH and need to remove one or more washers to lean out the mix. Now take the bike out for a test spin. LOW OR SLOW SPEED JETTING Now you can tune for low end performance. If you are getting a poor pickup or hesitation off the line, or a lot of backfiring on deceleration, then you need more fuel through the pilot jet. You increase fuel flow through the pilot jet by turning the pilot jet screw OUT a half turn. It’s best to start at 2 1/2 turns OUT on the pilot screws and then increase the turns OUT 1/2 turn at a time, and go for a test run. Do these until you get the performance you want and/or there are no back fires on deceleration. If you go more than 5 or 6 FULL turns out, you will probably have to install a LARGER pilot jets. Larger pilot jets are usually needed if you have removed the stock air intakes, air box and installed K & N filters which dramatically INCREASE air intake volume. I am not posting how to successfully repair the carburetor because of its complexity for a normal person. And friends, please make sure that a professional mechanic is always nearby if anything goes wrong. GENERAL PROBLEM SOLVING TIPS: If you get inconsistent running, fluctuations in power, you are probably running rich. Lean running is more likely to cut power completely. If you have poor power at small throttle openings and a surge at wider throttle then you may be running lean. Quick ways to see if you are running rich or lean. * APPLY CHOKE AFTER WARM – UP TO ARTIFICIALLY RICHEN THE MIXTURE. If you bike runs better with the choke on even after a few minutes of warm – up, your original mixture might be lean in the lower rev range. This test does strange things to the upper rev range, so don’t use it at highway speeds. * REMOVE THE AIR FILTER COVER AND ARTIFICIALLY LEAN OUT THE MIXTURE Temporarily remove the air liter cover (to INCREASE air to the mixture), and go for a test ride. A well tuned bike (where the air and fuel mix is right on) will run pretty badly (i.e. mixture too lean) when you do this. But if the mixture was originally too rich, the bike will run better. Then u can fix the air filter cover and lean the mixture.
If your bike’s performance has a hitch or hesitation at certain speeds or you can’t tell if it’s rich or lean, experiment by leaning out the mixture which is the easiest way to find out – if the mixture was originally too rich, the bike will run better immediately. If the mixture was originally too lean, your bike will run worse immediately (Use the tuning techniques listed above to adjust the low, mid- and high speed ranges). Now u might also understood why manufacturers stick to a particular setting and not going for extreme tuning. Extreme tuning will call the need for extreme keeping up of it. Friends, it’s all about experimenting with different settings. Also if found a good setting, don’t forget to check the fuel economy too. And always ride safe! Servicing CV Carbs
For the past few years we are getting CV (Constant Velocity) Carburetors in our motorcycles which are giving us very good performance and efficiency. Earlier the carbs were having round cylinder slide for throttling the engine which was directly connected to throttle cable. In CV carb. there are two throttles bodies, one is butterfly and another is round vacuum assisted cylinder. Butterfly slide connects directly to accelerator wire but round slide works on air and vacuum.
CV carbs. require special touch and understanding the construction. Earlier, mechanics used to clean carbs with some sharp needle and gasoline. But that used to damaged main, pilot jets and other tracks. By using sharp needle jet sizes used to get change. Which was not visible by regular eye and so it used to change the efficiency and performance. Now there are some cleaning liquids available in the market which can dissolve the carbon layer very fast and efficiently. Which also keeps the jets and carb body material intact. In CV carb. the most and delicate part is diaphragm, which can get damaged easily. Generally, carburetors are not cleaned often nowadays because of clean fuel. But sometimes we need to clean it due to tank rust or foreign material entry from intake side. So try to open till float chamber, where you can see main jet and pilot jet, use spray for cleaning and compressed air and re-assemble the carb properly with equal tightening. After cleaning and fixing the carb. put back to the intake manifold and start the engine. Set the air screw at 2.5 to 3 full turn or 5 to 6 half turn and set the RPM as per company slandered. But make sure while setting RPM engine is warm. Because cold engines requires little high RPM which shows which gives wrong reading at high temperature.
The exhaust should give you moisture feel or may be some water droplets. If you feel the moisture or water droplets that means you engine is properly tuned. Sometimes the carb float chamber gives cold feel or you can even see moisture on the float chamber. In some cases rider comes with acceleration problem. Check whether air screw is loose or not, because generally in CV carb. air screw gets jammed by oxidation deposition so always try to clean the air screw when ever you go for servicing. Check the diaphragm in light for small pin holes, if u see any hole then replace it. Then check the diaphragm whether it is working or not by blowing some amount of air in given holes. if the diaphragm is working then carb should be fine, but in this case you must check the diaphragm from both end of carb. First end is inlet manifold and second end is air filter end. Air filter end has got two holes on the top of carb. periphery, blow some air then the slide will activate. Next try to blow air from first end. The air should only activate slider, should not get leaked from any other side. If the air is entering through the slide or needle portion that means the carburetor body is increased by some microns. The ID of carb body which is provided for slider if it increases then the motorcycle will never go beyond 1200 to 1500 RPM or it may not stay at idle either, the bike will get heat and acceleration will slower down after some time. In that case carb. body or full carb. has to be changed, check and handle the carb very carefully and clean it from any of your skilled mechanic. All the given information is for understanding the CV carb and for maintenance, If you are a mechanic then handle the carb very carefully. But if you are not a mechanic then try not to open the carburetor alone. Make sure you are under observation of any skilled mechanic. Otherwise you may damage the carburetor. CV carburetor is one of the costly spare so you might get fooled or ask your mechanic to handle it very carefully. So keep your eyes open while your mechanic is working on it. Always use proper branded tools and sprays for repair. Your machine also need care just like our human body. Remember both the bodies are delicate. For more details about high performance and other technical things about bikes you can call us on +91 98222 12496 or you can mail us at [email protected] Common Problems All of us bike owners at some point of time must have come across problems with our machines, some may have been minor, some may have been a little serious, having ridden over 40,000 kilometres on my Apache 150, 2007, I figured my experiences would be of great help to all you riders out there. I’ve put together some of the most common problems that I and people that I have known have faced and all its solutions. As you may find out, some of it just requires a little effort from your part and nothing more, the best thing to do, though, would be to read your owner’s manual in your spare time as this will help you get a better understanding of the machine on the whole. Here we go…
Poor Performance
Another common complaint with bikes is the poor performance of the machine, this can happen after a while of ownership, there are several common reasons that you can look into as mentioned below Air Filter: The air filter is cleaned every time the bike is taken in for service, given the Indian riding conditions, it gets dirty after about a 1000Km’s, if you ride around the city or around dusty areas a lot, you must clean the air filter if you notice poor performance. Consult your owner’s manual as it will have stepby-step instructions on how to do so.
Fuel Quality: Poor quality of fuel can also be the reason for poor performance, different pumps have different mixes that claims to deliver better performance, rather than listening to recommendations, try filling up from different petrol pumps to find the fuel that gives the best feel and performance from your bike, the engine note may also change along with the fuel quality but it’s up to you to find out what the bike likes the most. Lack of Warm Ups: Warming up the engine in the morning starts is like how the gym instructor makes you warm up before you get into the exercise. It’s something that you must do every time, for an example, BMW’s have a rev counter in which the red line RPM increases as the engine temperature goes up, as the temperature reaches an optimum level, the red line RPM will be at its maximum. This is what we must follow ourselves, when properly warmed up in the morning, you will note that the engine feels better and performs well for the whole day. It’s just the little thing that you need to take care of. Also put the choke to good use in the mornings. Tyre Pressure: As tyre pressure is low, the rolling resistance increases, this lowers performance as well as efficiency, maintain it at the optimum levels at all times, check it at least once every month and fill up as needed. Low engine Oil: Running an engine on low oil can lead to serious damage of the engine components and in some cases can also be permanent, like seized pistons and other parts, if there is by chance any leak, have it checked immediately by a mechanic and if possible, tighten any bolts around the area where it leaks. Check the oil level every 2,500 Kilometers and top up if needed. Chain Slack: A slacking chain can make engine response feel poor and can also reduce the acceleration. If you hear a lot of chain noise or noise from the chain cover, its time you greased it up and tightened it. Carburettor Tuning: Improper A/F setting can also be the reason for low performance, Click on this link to find out how you can adjust it yourself, also remember not to do this if the bike is new or hasn’t run at least 7,500 Km’s as the service mechanics would do this themselves during that period. Carbon Build Up: When my bike was 30,000 Kilometers old, it couldn’t win a drag with the 150cc Fazer, which was much heavier and was ridden by a less experienced rider, this made me even think of selling it off. But then I told this to the TVS mechanic who recommended that I do an engine decarbonisation. This required me to leave the bike at the workshop for a whole day so that the engine head had to be removed, when I saw the piston, I was genuinely shocked, it was coated in a thick and dry carbon layer, it was so hard that you needed a screw driver to even scratch the surface, he told me that it was the reason why the bike didn’t go as fast as it should. After the cleaning and valve setting, I found that I could stay on par with the same Fazer. Performance was the same as what it was in the early days and now the needle touches 80 without me even knowing it. Considering that this is a 40,000Km and almost 3 year old machine, it is quite impressive.
Electric Starter Fails
This is a useful feature that can save us the embarrassment of causing a traffic jam after stalling the engine. You may find it not working on some fine morning. Check for the following signs: Battery level: The battery may have run out of acid which must have reduced its efficiency, if you notice that the starter works once you start riding for a long time, but doesn’t when you try in the morning, get the battery acid levels checked. Your bike charges the battery as you ride so just keep it filled up at the first signs of trouble. Starter Relay: This is part of the electric system that provides current to the starter, sometimes a failure of this component can stop the starter from working, if you hear just a “tick” noise from the starter every time you press the starter button, it may be either because of a low battery or a failing starter relay.
To Remember Your bike needs a little bit of care and attention if you would want it to last long just the way you like, so here are a few tips that can help you keep the bike and eventually yourself happy: 1. Warm Ups: Warm up the engine well in the mornings before you head out for a journey, this can help a lot in extending engine life and performance. 2. Check Tyre Pressure: Once a month, inspect the tires for signs of low pressure, keep them topped up for the best. 3. Chains: If you notice chain noise or looseness, simply get the chain tightened, its just a matter of 10 minutes at the most. 4. Periodic Service: Note that most bikes have a service interval of around 2,500 Kilometers, be sure to visit the service station in the specified intervals, check the manual to know more about the intervals. 5. Avoid Cheap Parts: If in case, a part does go bad, avoid replacing it with cheap alternatives or quick fixes, all manufacturers test parts for durability and quality and that is the way you should be going. So these are the simple points you should keep in mind, I have mentioned the most common problems faced by bike owners and their possible solutions, I know there are a lot more than this, but I will be sure to cover even more areas in Part 2 of this article. Meanwhile, if you own a bike and have come across problems, please share with us, how you managed to solve it, do mention the type of bike and the Kilometers it ran along with the comment.
Dear Biker,
• • • • • • •
Are you tired of cold starts? Need to raise the throttle everyday to get the cold engine running? Does someone have the same bike as yours and are you tired of losing to him in drag races? Suddenly, the fuel efficiency has reduced after a service? Has the mechanic has screwed up your tuning? Engine gives hiccups when you open the throttle? Or your bike is just missing that smooth acceleration whenever you want? Or your engine overheats even if you did not race too much.
May be the following will help you in tuning your mean machine for optimal power delivery and best fuel economy. This guide aims at tuning the fuel/air screw to give you an optimal air-fuel mixture. An optimal mixture gets maximum performance from your machine.
This Guide Applies To
All the single cylinder bikes, 2 stroke or 4 stroke having a carburetor. Tachometer is very handy and a must for a newbie or the tuning process will be very slow or painful or imperfect. Disclaimer: Though whatever I have written here wont do any damage to your machine, finally you must not blame me for whatever happens. I am here to help if anything goes wrong.
Getting Things In Action
Turn the idle settings screw so that rpm reaches about 3000 rpm. Now tune the air/fuel screw to make the mixture leanest as possible. Please refer to the above whether you must turn the screw clockwise or anti clockwise. As you make the mixture leaner, slowly the engine RPM decreases… Go on doing this until you have put the fuel screw to the leanest possible point. At the same time, ensure that the engine does not stall, by turning the idle-screw. Tough huh? You’ll get used to it OK the engine is running and the mixture is lean. If you notice from the engine sound OR if you see the tachometer, the engine RPM will not be steady at this point. Now very slowly start turning the fuel screw anti-clockwise, quarter to 1/8th turn at a time. You will notice that the RPM increases slowly and steadily. Again, do this very very slowly. Also count the total number of turns as you wind out the screw. You’ll notice that when you have turned it to about 3-4 full revolutions, the engine RPM slowly becomes constant. It is this point that you must stop screwing more. This probably is the optimal setting for your engine. Further on, try turning the screw even more and more to 5-7 revolutions and you’ll notice that the engine RPM will slowly decrease. When this happens, you are just putting in a too rich mixture in your engine. At this point the engine loses all the fuel efficiency and the mixture is not optimal. Repeat the process about 2-3 times. Count the revolutions each time and get the setting which you feel is correct. OK the engine is humming perfectly, now what? Decrease the idle setting screw to about 1000rpm in the tachometer. When the engine slows down, just twist the throttle. The response should be crisp and quick. It should not give any hiccups! Try shutting off the engine and restarting. The engine MUST start in a single kick or self with out giving throttle. If this happens, the setting is ok. Now get a ride and you’ll notice the difference for good or bad
You’ll immediately notice change in the engine sound and the throttle response. Your engine can become more smooth or harsh. Another important point is, Ride and Feel. Always take a ride and get the feel of the bike in each gears, check the response and the engine sound. You’ll quickly come to know once you get the feel of the bike that you want to make the mixture rich or lean. It may take a few iterations before you fix a setting as permanent. Try calculating the mileage per liter and tally it with your setting and the feeling you get. Troubleshooting Here are some symptoms and their quick solutions:
• • • • •
•
Engine dies while tuning. Try the process all over again. This time set the idle screw higher/faster. Engine gives hiccups while driving, specially while in higher gears. May be the mixture is too lean. Try again. Engine heats up. The mixture is too lean or too rich. Try again. Whenever I race up the engine, the rpm increases fast but very slowly comes down to idle. The mixture is not optimal, probably towards leaner side. Try again. Too much low end torque and the engine sound is very beaty/thumpy. You’ll face a low mileage surely, when you drive below 40kmphr. You have tuned on the higher/richer side. I have doubts or I have other problems. Why don’t you put in a comment?
How ti fit K&N filtetr and Rejet This post is for all my fellow bike riders who wish to extract the last possible juice out of your ride. This post is regarding to the fitting of free flow air filters, its effects and how to rectify it using the method of rejetting. You need to consider re-jetting your bike whenever there’s been a major change to the air intakes (like installing K&N filters which allow more air to pass to the carburetor), or adding drag pipes. Both modifications will lean out the air-fuel mix. The stock jet can only allow a certain amount of fuel to pass through and is designed according to the specification of the vehicle. Installing larger jets increases fuel to the carburetor to restore the 14 parts air to 1 part fuel optimum mix. This mixture is called stoichiometric ratio. Whenever the amount of air intake is increased, the fuel part is also to be increased. In all other cases, the stock jets will take you through 95% of your riding requirements.
Since the main jet effects all speed ranges after idle, you need to get the main jets right first, and then tune the mid-range and low end. All tuning should be done on a fully warmed up engine because that’s the way you usually ride; the spark plugs should have been previously checked and cleaned; the gas tank should be at least half full; a new or recently installed fuel filter if present; the air intake filters checked for holes, and cleaned; and all air intake and manifold connections tight and secure; the battery fully charged; and the carburetors synchronized, if it’s a multiple cylinder engine (more than one cylinder, eg: kinetic comet ) for optimum results. We are now going to tune the carburetor without the help of a tachometer (engine speed). High speed or top end main jet sizes are determined by full open throttle performance. Low and mid-range tuning is determined mainly by how the bike feels to you as you roll the throttle. Mikuni CV carburetor is different from the Keihin CV. So is the difference with other carburetors. So tuning will be different in different vehicles.
Note: If you do sense a loss of power, or rough running on a stock vehicle, it may due to some other reason. In this case re-jetting is not the solution to the current problem. Please take the bike to an authorized mechanic and rectify the problem. HIGH SPEED JETTING High speed performance (80 KPH and up) is controlled by the main jets. To make sure you have the right main jets, take your bike out to an open highway where you can safely (and legally) open the throttle all the way in top gear. Ride the bike full open and let the bike get to top speed. Again, do this only if you are experienced and comfortable running at top speed and you are not in danger of injuring yourself or someone else. A. If at top speed or before, the bike runs rough, heavy throttle feel or begins to hesitant and buck, your main jet is TOO BIG. The mix is too rich (more fuel than the optimum 1 part fuel to 14 parts air) and you are getting an uneven burn and poor performance. Install smaller main jets and take the bike for another test run. Another way to determine rich mixture is, when u cold start the vehicle and if the bike starts in the very first crank the mixture is rich (no need to use the choke in this instance). Low fuel efficiency and more smoke in the exhaust than usual are some of the characteristics of a rich mixture. B. If before top speed the engine is running smooth, but has no power, seems to be running hot or knocking from the engine and you can’t push the bike to top speed, then your main jets are too SMALL. You are running too LEAN a mix (less fuel than the optimum 1 part fuel to 14 parts air) for maximum engine performance. Put in LARGER main jets and take the bike out for another test run. Another way to determine lean mixture is the difficulty u feel when cold starting. Even after repeated cranking, if the engine does not start, the mixture is lean. When u closes the throttle in a downhill, if u hears popping or cracking sound from the exhaust, it is again due to the lean mixture.
MID-RANGE OR MID-SPEED TUNING The carburetor needle controls mid-range performance. The needle tapers down to a point that fits into the main jet. The needle is lifted upward (along with the slide) by the carburetor diaphragm as the air flow increases through the carburetor. As the needle moves upward it is withdrawn from the main jet, allowing more fuel to mix with the increased air volume. All that is needed to modify mid-range performance is to place (or remove) one or more small, thin washers between the diaphragm and the head of the carburetor needle where it’s held in the diaphragm. Adding washers effectively raises the tapered needle further out of the main jet at all engine rpm’s and allows more fuel to mix with air to create a richer mix. Removing a washer effectively leans out the air-fuel mix. There’s usually no need to replace the stock needles since they have proven over time to provide good performance and good gas mileage. If you do use a third party needle for increased performance, then anticipate lower fuel efficiency. Mid-range tuning is accomplished mainly by how the bike performance feels to you. If there’s a smooth increase in power as you roll the throttle, then you’re there. If there’s a slow response or there’s no power, then the mix may be too LEAN and you may need to add one or more washers to richen the mix. If the bike accelerate with power, but feels rough, you may be too RICH and need to remove one or more washers to lean out the mix. Now take the bike out for a test spin. LOW OR SLOW SPEED JETTING Now you can tune for low end performance. If you are getting a poor pickup or hesitation off the line, or a lot of backfiring on deceleration, then you need more fuel through the pilot jet. You increase fuel flow through the pilot jet by turning the pilot jet screw OUT a half turn. It’s best to start at 2 1/2 turns OUT on the pilot screws and then increase the turns OUT 1/2 turn at a time, and go for a test run. Do these until you get the performance you want and/or there are no back fires on deceleration. If you go more than 5 or 6 FULL turns out, you will probably have to install a LARGER pilot jets. Larger pilot jets are usually needed if you have removed the stock air intakes, air box and installed K & N filters which dramatically INCREASE air intake volume. I am not posting how to successfully repair the carburetor because of its complexity for a normal person. And friends, please make sure that a professional mechanic is always nearby if anything goes wrong. GENERAL PROBLEM SOLVING TIPS: If you get inconsistent running, fluctuations in power, you are probably running rich. Lean running is more likely to cut power completely. If you have poor power at small throttle openings and a surge at wider throttle then you may be running lean. Quick ways to see if you are running rich or lean. * APPLY CHOKE AFTER WARM – UP TO ARTIFICIALLY RICHEN THE MIXTURE. If you bike runs better with the choke on even after a few minutes of warm – up, your original mixture might be lean in the lower rev range. This test does strange things to the upper rev range, so don’t use it at highway speeds. * REMOVE THE AIR FILTER COVER AND ARTIFICIALLY LEAN OUT THE MIXTURE Temporarily remove the air liter cover (to INCREASE air to the mixture), and go for a test ride. A well tuned bike (where the air and fuel mix is right on) will run pretty badly (i.e. mixture too lean) when you do this. But if the mixture was originally too rich, the bike will run better. Then u can fix the air filter cover and lean the mixture.
If your bike’s performance has a hitch or hesitation at certain speeds or you can’t tell if it’s rich or lean, experiment by leaning out the mixture which is the easiest way to find out – if the mixture was originally too rich, the bike will run better immediately. If the mixture was originally too lean, your bike will run worse immediately (Use the tuning techniques listed above to adjust the low, mid- and high speed ranges). Now u might also understood why manufacturers stick to a particular setting and not going for extreme tuning. Extreme tuning will call the need for extreme keeping up of it. Friends, it’s all about experimenting with different settings. Also if found a good setting, don’t forget to check the fuel economy too. And always ride safe! Servicing CV Carbs
For the past few years we are getting CV (Constant Velocity) Carburetors in our motorcycles which are giving us very good performance and efficiency. Earlier the carbs were having round cylinder slide for throttling the engine which was directly connected to throttle cable. In CV carb. there are two throttles bodies, one is butterfly and another is round vacuum assisted cylinder. Butterfly slide connects directly to accelerator wire but round slide works on air and vacuum.
CV carbs. require special touch and understanding the construction. Earlier, mechanics used to clean carbs with some sharp needle and gasoline. But that used to damaged main, pilot jets and other tracks. By using sharp needle jet sizes used to get change. Which was not visible by regular eye and so it used to change the efficiency and performance. Now there are some cleaning liquids available in the market which can dissolve the carbon layer very fast and efficiently. Which also keeps the jets and carb body material intact. In CV carb. the most and delicate part is diaphragm, which can get damaged easily. Generally, carburetors are not cleaned often nowadays because of clean fuel. But sometimes we need to clean it due to tank rust or foreign material entry from intake side. So try to open till float chamber, where you can see main jet and pilot jet, use spray for cleaning and compressed air and re-assemble the carb properly with equal tightening. After cleaning and fixing the carb. put back to the intake manifold and start the engine. Set the air screw at 2.5 to 3 full turn or 5 to 6 half turn and set the RPM as per company slandered. But make sure while setting RPM engine is warm. Because cold engines requires little high RPM which shows which gives wrong reading at high temperature.
The exhaust should give you moisture feel or may be some water droplets. If you feel the moisture or water droplets that means you engine is properly tuned. Sometimes the carb float chamber gives cold feel or you can even see moisture on the float chamber. In some cases rider comes with acceleration problem. Check whether air screw is loose or not, because generally in CV carb. air screw gets jammed by oxidation deposition so always try to clean the air screw when ever you go for servicing. Check the diaphragm in light for small pin holes, if u see any hole then replace it. Then check the diaphragm whether it is working or not by blowing some amount of air in given holes. if the diaphragm is working then carb should be fine, but in this case you must check the diaphragm from both end of carb. First end is inlet manifold and second end is air filter end. Air filter end has got two holes on the top of carb. periphery, blow some air then the slide will activate. Next try to blow air from first end. The air should only activate slider, should not get leaked from any other side. If the air is entering through the slide or needle portion that means the carburetor body is increased by some microns. The ID of carb body which is provided for slider if it increases then the motorcycle will never go beyond 1200 to 1500 RPM or it may not stay at idle either, the bike will get heat and acceleration will slower down after some time. In that case carb. body or full carb. has to be changed, check and handle the carb very carefully and clean it from any of your skilled mechanic. All the given information is for understanding the CV carb and for maintenance, If you are a mechanic then handle the carb very carefully. But if you are not a mechanic then try not to open the carburetor alone. Make sure you are under observation of any skilled mechanic. Otherwise you may damage the carburetor. CV carburetor is one of the costly spare so you might get fooled or ask your mechanic to handle it very carefully. So keep your eyes open while your mechanic is working on it. Always use proper branded tools and sprays for repair. Your machine also need care just like our human body. Remember both the bodies are delicate. For more details about high performance and other technical things about bikes you can call us on +91 98222 12496 or you can mail us at [email protected] Common Problems All of us bike owners at some point of time must have come across problems with our machines, some may have been minor, some may have been a little serious, having ridden over 40,000 kilometres on my Apache 150, 2007, I figured my experiences would be of great help to all you riders out there. I’ve put together some of the most common problems that I and people that I have known have faced and all its solutions. As you may find out, some of it just requires a little effort from your part and nothing more, the best thing to do, though, would be to read your owner’s manual in your spare time as this will help you get a better understanding of the machine on the whole. Here we go…
Poor Performance
Another common complaint with bikes is the poor performance of the machine, this can happen after a while of ownership, there are several common reasons that you can look into as mentioned below Air Filter: The air filter is cleaned every time the bike is taken in for service, given the Indian riding conditions, it gets dirty after about a 1000Km’s, if you ride around the city or around dusty areas a lot, you must clean the air filter if you notice poor performance. Consult your owner’s manual as it will have stepby-step instructions on how to do so.
Fuel Quality: Poor quality of fuel can also be the reason for poor performance, different pumps have different mixes that claims to deliver better performance, rather than listening to recommendations, try filling up from different petrol pumps to find the fuel that gives the best feel and performance from your bike, the engine note may also change along with the fuel quality but it’s up to you to find out what the bike likes the most. Lack of Warm Ups: Warming up the engine in the morning starts is like how the gym instructor makes you warm up before you get into the exercise. It’s something that you must do every time, for an example, BMW’s have a rev counter in which the red line RPM increases as the engine temperature goes up, as the temperature reaches an optimum level, the red line RPM will be at its maximum. This is what we must follow ourselves, when properly warmed up in the morning, you will note that the engine feels better and performs well for the whole day. It’s just the little thing that you need to take care of. Also put the choke to good use in the mornings. Tyre Pressure: As tyre pressure is low, the rolling resistance increases, this lowers performance as well as efficiency, maintain it at the optimum levels at all times, check it at least once every month and fill up as needed. Low engine Oil: Running an engine on low oil can lead to serious damage of the engine components and in some cases can also be permanent, like seized pistons and other parts, if there is by chance any leak, have it checked immediately by a mechanic and if possible, tighten any bolts around the area where it leaks. Check the oil level every 2,500 Kilometers and top up if needed. Chain Slack: A slacking chain can make engine response feel poor and can also reduce the acceleration. If you hear a lot of chain noise or noise from the chain cover, its time you greased it up and tightened it. Carburettor Tuning: Improper A/F setting can also be the reason for low performance, Click on this link to find out how you can adjust it yourself, also remember not to do this if the bike is new or hasn’t run at least 7,500 Km’s as the service mechanics would do this themselves during that period. Carbon Build Up: When my bike was 30,000 Kilometers old, it couldn’t win a drag with the 150cc Fazer, which was much heavier and was ridden by a less experienced rider, this made me even think of selling it off. But then I told this to the TVS mechanic who recommended that I do an engine decarbonisation. This required me to leave the bike at the workshop for a whole day so that the engine head had to be removed, when I saw the piston, I was genuinely shocked, it was coated in a thick and dry carbon layer, it was so hard that you needed a screw driver to even scratch the surface, he told me that it was the reason why the bike didn’t go as fast as it should. After the cleaning and valve setting, I found that I could stay on par with the same Fazer. Performance was the same as what it was in the early days and now the needle touches 80 without me even knowing it. Considering that this is a 40,000Km and almost 3 year old machine, it is quite impressive.
Electric Starter Fails
This is a useful feature that can save us the embarrassment of causing a traffic jam after stalling the engine. You may find it not working on some fine morning. Check for the following signs: Battery level: The battery may have run out of acid which must have reduced its efficiency, if you notice that the starter works once you start riding for a long time, but doesn’t when you try in the morning, get the battery acid levels checked. Your bike charges the battery as you ride so just keep it filled up at the first signs of trouble. Starter Relay: This is part of the electric system that provides current to the starter, sometimes a failure of this component can stop the starter from working, if you hear just a “tick” noise from the starter every time you press the starter button, it may be either because of a low battery or a failing starter relay.
To Remember Your bike needs a little bit of care and attention if you would want it to last long just the way you like, so here are a few tips that can help you keep the bike and eventually yourself happy: 1. Warm Ups: Warm up the engine well in the mornings before you head out for a journey, this can help a lot in extending engine life and performance. 2. Check Tyre Pressure: Once a month, inspect the tires for signs of low pressure, keep them topped up for the best. 3. Chains: If you notice chain noise or looseness, simply get the chain tightened, its just a matter of 10 minutes at the most. 4. Periodic Service: Note that most bikes have a service interval of around 2,500 Kilometers, be sure to visit the service station in the specified intervals, check the manual to know more about the intervals. 5. Avoid Cheap Parts: If in case, a part does go bad, avoid replacing it with cheap alternatives or quick fixes, all manufacturers test parts for durability and quality and that is the way you should be going. So these are the simple points you should keep in mind, I have mentioned the most common problems faced by bike owners and their possible solutions, I know there are a lot more than this, but I will be sure to cover even more areas in Part 2 of this article. Meanwhile, if you own a bike and have come across problems, please share with us, how you managed to solve it, do mention the type of bike and the Kilometers it ran along with the comment.
