ok so im putting on a new exhaust system and read that i will need to re-jet the carbs. how do i know what size jets i will need, sorry if thats a silly question, i dont wanna be loosing any power tho!!!!!

 

You won't. You need to buy a jet kit and follow the tuning instructions. Main jets , needles , needle height , pilot.

 

and balance the carbs through trial and error, ie checking the plugs after a run etc? damn, i was afraid of that, probably easier to jus let a shop do it, any ideas how much they will charge??? if im gonna be buying new jets, whats the best i can get? cheers.

 

I had mine done 8 yrs ago and it was about $500 with the kit, As for jets if you can figure out the sizes you need. Try Jetsrus, For a full system I would say around a 125 main jet

 

Honestly it's not that difficult , it just takes patience.

You really don't need to balance the carbs just because of this.

After you put the new pipe on it will be lean , probably all over. You start with the main jets. They are your wide open throttle setting. At first , it won't pull all the way to redline , you go larger in main jet size till it does smoothly. When you buy the kit , like a Dynojet or Factory or whatever , it will come with larger jets , in order , bigger than stock. Don't worry about the numbers cause different manufactures sometimes use different numbers. Work your way up till it pulls hard all the way.

When you get that then you set the needles. That is roughly your wide open throttle through the midrange. Same deal there , change needles (included in kit) till you get smooth even performance.

Then your needle height , this is like full throttle from say 2-3k rpm.

Then your pilot screws. That's pretty much everything at partially cracked throttle and all your lower cruising speeds.

Once you get it all ballparked , you can fine tune. 2 best ways are sparkplug color and temperture changes. For sparkplugs , run the bike at the area you want to check and kill the motor instantly right there. That will lock in that condition. Check the plugs and adjust from there. this works well for all the upper RPM stuff. The other is temp changes. This is pretty simple. When the bike is literally cold , it will/should be a bit lean and when it is at temperature it should be perfect. This is really evident at idle and cruise. If it get worse as it warms up your probably too rich and vice versa.

Honestly , I really like tuning it myself cause I'm the only one that rides the way I do. You can tailor the tune really finely to your needs. A service guy is going to do the whole job in the preset allotted time , which is probably close enough but it's not going to be tuned to "you". Plus, it gives you a great understanding of how the whole fuel delivery system functions and will make you a better tuner and trouble shooter for it.

 

wow, thank you so much for all that info zaqwert6, now im gonna have to print that little bible out!! cheers buddy.

 

when you say run the bike then kill it, you mean actually riding it and kill it? WHat does killing it do? I don't understand when you say 'set the condition'

 

Ride the bike. At the exact point in the range that you want to get a read from the plugs , hold the speed/rpm whatever for a second or 2 and then shut off the engine. Hit the run/stop switch or whatever without doing anything else. When the engine dies , the plugs will retain the color and condition of the burn that existed at that exact moment.

You'll have to coast to a stop and pull a plug. It's best to do this in an area where you can work or hope you have understanding neighbors.

Wide open stuff I do at the track. But an open backroad will work if you have one. Everything else you probably can do around your neighborhood.