float and jetting adjustments

[sodflyer]

Adjusting the float's on my 250 and 85 bikes, in the manual it gives a range in height and says that the tang should be resting on the valve but not pressing down on it. No thios might be clear to you guys but are they talking about the inner springed shaft that's sticking out of the valve or they talking about the valve body. I adjusted the 85 lastnight, it said it should be between 71 and 79 but from the factory it was reading 60. so that could be the thick goo puking out of the tail pipe... also I have the jets on the lean side of the factory range so should I change them back to the stock jets after this float adjustment then start re-jetting from there if needed or keep the leaner jets in there and go with it? thanks for any help...I feel im close to getting this nailed down :) Jeff.

 

[sodflyer]

owhhh come on folks.......you know the answer :)

 

[JohnScott]

As far as where to measure float height: you measure it when the tang is just touching the float valve but not depressing it. There is a pretty good guide on the internet if you do a Yahoo search for Keihin. Sudco used to have some good tuning guides but I haven't been there in a while to know if they still do.

As far as jetting goes, I've had luck with my YZ250 leaning it out two sizes on the pilot and then using the shop manual as a guide on the needle clip position and main jet. I have found YZs to be pretty close from the factory - just a little rich on the bottom. I have a 2000 and 2001, BTW.

John

 

[SULLY]

I have always found this adjustment tricky, and pretty meaningless actually. You are adjusting when the tang meets the valve, but this does not take into account friction, mechanical binds, variation in float bouyancy etc....when what you actually want to acheive is an known height of fuel in the bowl.

I have never had one, but I reckon the screw in type fuel height tool must be a better way to go. If you haven't seen one it screws in where the bowl drain plug goes, and has a transparent pipe which you can hold against the side of the cab and see where the actual fuel height is settling.

Come to think of it I may even have a bash at knocking a home made varsion in the garage.

 

[motodr9]

float height made easier

This will sound a little wacky, but follow me here. The best way I've found to set the float height is to attach some fuel line (preferably new/clean) to the carb with the bowl off, then blow into the fuel line and see where the float needle closes. Use a small metric ruler held next to the float and move float up and down gently. See, hear, and feel when it opens and closes. Repeat as many times as you need, before becoming satisfied with the result. Resist urge to purchase hooka and watch Cheech and Chong movies.

 

[04-yz-250]

The float bowl on my bike was waaaay off from factory; now it alway's start's with second kick and I jet it as the manual say's for sea level.Grab float bowl in right hand and with first finger move the float just as tang touches pin. With vernier caliper's in left hand measure proper distance for height.picture in manual show's where to measure properly.I tried how other's are turning the float bowl upside down but I couldn't get a proper measurement.