idle problems. need HELP!!!

[shinzon1]

well i think i figured the idle problem out. it would only do it when it was good and hot. i think it was vapor locking. the fuel hose ran up just a little and i think it wasn't getting enough fuel. but i'm still having the other symptoms of it running lean. i just can't figure out why it started running lean. when i first got it u couldn't keep sparkplugs in it. it ran incredibly rich! now i can't get enough fuel to it. i've got the fuel screws out 3 turns and its enough for it run smoothly but wont put any color in the plugs. the insulator is just white. the ground strap is a light gray.

 

[Guest]

I find it odd that vapor lock would show up at idle only; it's usually the other way around, as you are using a lot less fuel at idle and the bowls have time to fill again.

It sounds to me like someone stuffed with the jetting on these carbs before & didn't get it right. I believe that Y64 needle is from a Keyster aftermarket carb kit; the stock needle should be a 5DL36 for 1979 or 5F21 if earlier. So I'm not sure where the clip on the needle should be set.

But as i stated in an earlier post I reckon you are lean on the needle and compensating with the fuel screws. I would try the needle one clip richer and put the pilot screws at 1 for fuel and 1 1/2 for air and see how it goes. But first try and get some info on that needle and see if there is a stock position for it. I've read mixed reports on tuning carbs with those needles. You may be better off in the long run sourcing stock needles and then everyone on here and you know what they're dealing with. That's if the needles are the problem.... .

 

[shinzon1]

ok. i think i may know where some of the stock needles are, but would that affect it at idle though? because with them turned one turn out it will barely idle. when u try to rev it will stumble and try to cut out. i can see where the needle would affect that part just not idle? i'll try that, but it may be few days.

 

[Guest]

ok. i think i may know where some of the stock needles are, but would that affect it at idle though? because with them turned one turn out it will barely idle. when u try to rev it will stumble and try to cut out. i can see where the needle would affect that part just not idle? i'll try that, but it may be few days.

You probably are correct about the needle not directly effecting the idle with closed throttle; but there is a relation between the pilot settings and the needle circuit. You've got your mixture screw out at 3 turns to give extra juice to the lean needle so you don't die when you rev like you mention.

I reckon you could get a nice even idle with fuel screws at say 1 1/4 turn and turning the airscrews in a little if you try. But as you said the bike will die when you rev it.

 

[GS750]

It does still sound like an air leak or you are very lean. This may be the float level as steve said. But after 30 odd years the buoyancy of the floats can differ from how they left the factory.


This is really the only way to know the fuel level in the carbs and rule float height out as a factor.

EXACTLY right!!! Mine was the same as yours, the "wet level" does not lie and mine were also 4-5mm variance even though I set them on the bench and was extremely careful!

 

[shinzon1]

i'm definately interested in those 110 mains chuck. i sent u a PM did u get it?

 

[shinzon1]

ok. so i found the original needles. 3 of them r 5dl36 and one is a 5dl35. what is the 5dl35 out of? also one of the 36s has a slight bend near the point will that hurt anything? the whole thing just looks a little bowed but u can barely see it.