How to fine-tune your jetting: Difference between revisions
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The best solution is taking the bike to a professional with a Dyno and an EGA (electronic gas analyzer, sometimes called a "Sniffer" or "4 gas analyzer") to see what kind of exhaust the bike is putting out at the different RPMs while under appropriate load. The next best solution is to dive head and heels into the massive amount of jetting information that's been published. There are dozens of different books dedicated to the subject. You'll have to read, then apply the information learned so you can feel what lean and rich are like. There's absolutely no way to impart that knowledge in the space of the FAQ. | The best solution is taking the bike to a professional with a Dyno and an EGA (electronic gas analyzer, sometimes called a "Sniffer" or "4 gas analyzer") to see what kind of exhaust the bike is putting out at the different RPMs while under appropriate load. The next best solution is to dive head and heels into the massive amount of jetting information that's been published. There are dozens of different books dedicated to the subject. You'll have to read, then apply the information learned so you can feel what lean and rich are like. There's absolutely no way to impart that knowledge in the space of the FAQ. | ||
You may want to [[Battery box mod for easier carb removal|modify the battery box]] if you are going to put an aftermarket exhaust on your bike or otherwise plan on rejetting. Why? Because the physical carb adjustment is simple. It's the fine tuning process that can be time consuming and tedious. It will require you to pull the carbs AT LEAST TWICE (if you are extremely lucky), but probably more like three or four times to get everything right. | |||
==Carb adjustment== | ==Carb adjustment== | ||
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Remove the black covers on the top of the carbs. The screws have different lengths, so keep track of which one goes where. The plastic vacuum pistons are held under pressure by a spring, so be careful when removing the top. | Remove the black covers on the top of the carbs. The screws have different lengths, so keep track of which one goes where. The plastic vacuum pistons are held under pressure by a spring, so be careful when removing the top. | ||
Carefully pull the vacuum diaphragm/piston unit out. The rubber diaphragm is the most delicate part of the carb | Carefully pull the vacuum diaphragm/piston unit out. The rubber diaphragm is the most delicate part of the carb and is easily damaged. | ||
Shake the needle out, raise it with (however many) 2.5 or 3 mm washers. | Shake the needle out, raise it with (however many) [[Washers for carb needles|2.5 or 3 mm washers]]. | ||
*If you're using aftermarket needles, start with the clip in the 3rd position (middle). This is usually for a stock or mildly modified setup, such as a slip-on exhaust. You can use washers to make "half" steps, too, for super-fine tuning. | |||
Reassemble. | Reassemble. | ||
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Raising the needles can actually be done without removing the carbs from the bike. Pull the tank, without pulling the upper fairing. You'll need a good-condition #2 phillips screwdriver with a shaft about 10" long. A multi-bit screwdriver won't work because the shaft is too thick. Just slide the screwdriver through the brackets to pull the screws out, pop the cover off, pull the springs, and fish out the vacuum pistons. Make your adjustments and reassemble. Make sure to drop the needle straight down, so that it goes into the collar above the emulsion tube; you can easily see if it doesn't. Put the screws and brackets back on, and you're good to go. | Raising the needles can actually be done without removing the carbs from the bike. Pull the tank, without pulling the upper fairing. You'll need a good-condition #2 phillips screwdriver with a shaft about 10" long. A multi-bit screwdriver won't work because the shaft is too thick. Just slide the screwdriver through the brackets to pull the screws out, pop the cover off, pull the springs, and fish out the vacuum pistons. Make your adjustments and reassemble. Make sure to drop the needle straight down, so that it goes into the collar above the emulsion tube; you can easily see if it doesn't. Put the screws and brackets back on, and you're good to go. | ||
The big key to this is to not have sticky bolts... If they are stuck, you'll need to pull the carbs so you can put them in a bench vise and hit them with an impact driver. | The big key to this is to not have sticky bolts... If they are stuck, you'll need to pull the carbs so you can put them in a bench vise and hit them with an impact driver. | ||
====Step 4: [[Removing idle mixture screw plugs|Adjust mixture screws]]==== | ====Step 4: [[Removing idle mixture screw plugs|Adjust mixture screws]]==== | ||
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====Step 5: [[How do I remove the carbs to work on them?|Attach carbs to bike]]==== | ====Step 5: [[How do I remove the carbs to work on them?|Attach carbs to bike]]==== | ||
==Carb Tuning== | ==Carb Tuning== | ||
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Symptoms: | Symptoms: | ||
LEAN = Blipping throttle causes the | LEAN = Blipping throttle causes the rpm to rise, hang for a moment, then drop back down. | ||
RICH = Blipping throttle causes the | RICH = Blipping throttle causes the rpm to rise, drop down below the idle speed setting, and the rise back up. | ||
==Conclusions== | ==Conclusions== | ||