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help me please with carb adjustment
Posted: Sun Jul 17, 2011 3:00 am
by millermike
I just opened up carbs on 1981 xj 650. and both air screws are turned all the way tight. how far out should they be ruffly.
Re: help me please with carb adjustment
Posted: Sun Jul 17, 2011 3:11 am
by HYPERR
Hard to say for sure but most bikes I've tinkered with seems to like around 2 turns out. Depends on the elevation too. I would do 2 turns out and then tweak it from there. Do you have access to them after the carb in on the bike? I usually put T-handle screws so I can mess with them afterwards.
Re: help me please with carb adjustment
Posted: Sun Jul 17, 2011 3:13 am
by millermike
no there inside carb 2 brass jets, im not sure if im even adjusting right screws there both tightened all the way down.
Re: help me please with carb adjustment
Posted: Sun Jul 17, 2011 3:15 am
by HYPERR
millermike wrote:no there inside carb 2 brass jets, im not sure if im even adjusting right screws there both tightened all the way down.
Are you talking about the jets or the mixture screw???
Re: help me please with carb adjustment
Posted: Sun Jul 17, 2011 3:18 am
by millermike
im trying to adjust mixture screw but im dummy, not really sure were located and cant afford to take it in
Re: help me please with carb adjustment
Posted: Sun Jul 17, 2011 3:34 am
by HYPERR
millermike wrote:im trying to adjust mixture screw but im dummy, not really sure were located and cant afford to take it in
You have the carbs out and apart?
You have four carbs, yes?
They are Minkuni CVs?
Re: help me please with carb adjustment
Posted: Sun Jul 17, 2011 3:36 am
by millermike
no just pulled needle valve out. my bike is running real lean and i need the mixture screw adjusted
Re: help me please with carb adjustment
Posted: Sun Jul 17, 2011 3:46 am
by millermike
4 carbs its a xj 650
Re: help me please with carb adjustment
Posted: Sun Jul 17, 2011 3:53 am
by HYPERR
millermike wrote:no just pulled needle valve out. my bike is running real lean and i need the mixture screw adjusted
What do you mean you pulled the needle valve out?
What you are talking about is the pilot screw. Those are usually capped with plastic caps or metal caps that have to be drilled out depending on the year of the bike and the severity of the emission standard of that year. I'm not sure if they even capped them in 1981, if they did, it might just be a plastic cap.
The pilot screw only adjusts the mixture at idle so it won't help much for the lean condition at rpms much above idle. For those you will need to change the jets and adjust or get a new needle.
As for the pilot screw, as a baseline, turn the pilot screw to a position that allows the highest idle. Then adjust the idle screw to get the idle back down to where it's supposed to be.
Re: help me please with carb adjustment
Posted: Sun Jul 17, 2011 3:55 am
by HYPERR
millermike wrote:4 carbs its a xj 650
Yes correct.
Are they mikunis?