Quote:
Originally Posted by Douglass
Megadan - Thank you so much! you gave an excellent explanation. I am really trying to learn the functions. Of erverything on the bike this is probably the only thing that I am a little intimidated by. I can tune my car using a computer, but have the nessessary gauges to see what my fuel trims and WOT fuel readings are. If/when I decide to change the carb on my bike, I want to be able to do things with purpose, and understanding rather than guess and hope.
Thanks again, your explination I know took time to type up, and it is greatly appricated!
Douglass
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It was my pleasure guys. Just remember that my explanation is pretty simplified, but if you do a little google searching you can come up with all sorts of information that will go more in depth than I did.
If you really want to get into tuning, you can always install a wideband O2 on the exhaust to really aid in dialing in carb tuning. Kind of an expensive route to go, but it can always be used on other bikes in the future. Simply put a plug in the sensor bung when not in use.
The old fashioned way is to read the spark plug. You can find a charts like this one to help point you in the right direction.
http://bustekhub.com/wp-content/uplo...on-Chart-1.png
Really, once you start messing with carb tuning you realize how simple it really is.
The only other thing to really keep in mind is that since these carbs are purely mechanical in nature, if the air density altitude changes via temp swings or large enough elevation changes, the bike will run leaner or richer.
The general rule of thumb with Mikuni jetting is a full jet size per 5000ft altitude or 50 degree change in temp. Aka, you have a 115 main jet that is perfect in 90 degree temps, once the air temp drops below 40 degrees it is a good idea to step up a jet size to a 120, or at least half a step like a 117.5