idle problems. need HELP!!!

[shinzon1]

i've been having with carbs since i've owned the bike. nearly a year now. when i first got it it was running way to rich. i'd foul out a set of plugs in about 400 miles. i pulled the carbs to see if there was anything i could see. i noticed the floats were set to high. i set to the proper 26mm with gasket removed. cylinders 1,2, and 4 still ran rich but not as bad. cylinder 3 immediatley started running to lean. only white insulator. i kept tinkering with it for a while then just gave up for a while. i pulled the carbs a few weeks later to check them again. i checked to see where the air and fuel screws were at. the air screws were 2 turns out on all cylinders and the fuel were out 3 full turns on all of them. so i tryed setting the fuel screws to 1 turn out and it wouldn't even run. i then ran them back out to the 3 turns. all cylinders ran to lean. i pulled them and tore them apart. noticed one of the screws had broken off inside. got that fixed and let them soak in carb dip for a week. put everything back together correctly and all cylinders seem to run lean cuz i can't get any color on any of the plugs. it revs fine. pulls all the to redline. no hickups or anything, except at idle. idle is all over the place it might idle at 1500 or slowly start falling till it finally cuts out. it just kinda jumps all over the place. the carb holders are good and flexible the orings are brand new. check for air leaks and can't find any, and the valves are all in spec. please help!

 

[Guest]

What are your pilot screws set at now? And what filter and exhaust are you running?

 

[Steve]

i noticed the floats were set to high. i set to the proper 26mm with gasket removed.

I don't have the specs for the '79 carbs, but the '78 carbs were to be set at 23.0 +/- 1.0 mm. Setting them at 26 will make them run lean.

the air screws were 2 turns out on all cylinders and the fuel were out 3 full turns on all of them.

If you have stock airbox and exhaust, the fuel screws (on the bottom) should be out about 3/4 turn. The air screws (on the side) should be out about 1 1/2 turn.

so i tryed setting the fuel screws to 1 turn out and it wouldn't even run. i then ran them back out to the 3 turns. all cylinders ran to lean.

This is probably because the float level is too low.


.

 

[shinzon1]

the filter is a stock foam filter with stock airbox. the exhaust is the mac 4 into 2. im not a big fan of it. it was on the bike when i got it. they r set between 2 and 3 turns out. 3 and 4 run more lean than the others i have them set at 3 and 1 and 2 are 2 turns out. ive tryed messing with them and it keeps doing the same.

 

[shinzon1]

i went ahead and put them back to where they were when i got them which im pretty sure is right around 20mm to 23mm. but im still running lean. the bike runs fine off idle on up. im just having trouble with idle.

 

[Guest]

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.

So rather than pulling the carbs and measuring 24mm or 26mm exactly and thinking they're right; the only way to really know what is happening with your fuel level, is by checking it with clear tubing - running from the drain screw hole in the bottom of the carb to the mating surface of the carb body with the float bowl. The fuel should sit about 3mm below this. Search the forums or check the manual further for more details & photos of this if you like.

When I checked mine there was 4mm difference between the carbs and the floats were set all exactly the same. One was 4mm below the mating surface and another sat right on it. The other two were in between. So my float heights ended up between 25 - 28mm to get the correct wet fuel level in the bowl.

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

 

[shinzon1]

this might be a dumb question but how can i get the tube to connect to the fuel bowl drain without fuel spilling everywhere?

 

[fishfarm]

this might be a dumb question but how can i get the tube to connect to the fuel bowl drain without fuel spilling everywhere?

Here's a thread that should help:

http://www.thegsresources.com/_forum/showthread.php?t=169615

 

[shinzon1]

ok. thanks guys! i'll try that out this weekend and let u know what i find.

 

[Guest]

Just a thought. Did you record the other carb settings when you pulled the carbs? i.e. needle height/position. If your not getting any colour on your plugs and idles a mess, too lean a needle can cause these symptoms but you'll still go pretty fast when warm. You may be compensating for this with the pilot fuel screw settings.

Check you floats first anyway cause you want them to be right regardless.

 

[shinzon1]

the needles are on the 2nd from the top slot. which is where they were when i got it. going to be checking the float height this afternoon. i'll post again as soon as i check them.

 

[shinzon1]

ok so i checked the float levels. they r all good. if anything they r a hair on the high side but still within tolerance. any other ideas?

 

[shinzon1]

well i guess i'm just run it till dies. it runs and i'm sick of screwing with this thing. thanks for all your help guys.

 

[chuck hahn]

We need to know all the following info..you already told us your running a 4 into 1 pipe. You have also checked the float heights.

Now take the floats and float needles out and remove the float seats and be sure the screens under the seats are clean..or even there.
What size are the MAIN jets?
What size are the PILOT jets?
Whats the numbers on the NEEDLE jet..the long one attatched to the slides?
Have you dipped all the metal parts and needles in carbs dip for at least 12 hrs?
Have you dipped each carb body as well?
Have you rinsed the parts in carb spary and used compressed air to blow thru all the passages and the jets after they came out of the carb dip?
Have you taken a small wire and cleaned all the holes in the jets and the emullsion tubes?
Have you replaced all the orings in the crabs?
Have you replaced the orings between the intake pipes and the engine? They may look and feel fine, but still not be perfect.
Once all this info is provided the guys WILL be able to assess the situation properly and advise the proper jets and settings to get them in the ball park for you..I know cuz i just got one heck of an education just this weekend and they got them and me dialed in almost pefectly. I know its frustrating and youre getting really pizzed, but hang in there. Also read my thread called Carbs Mechanic Wanted,, All the things i went thru is right there and all the coaching they gave me is there also. I think it will help you out a lot to check it out.

 

[rustybronco]

What does the voltage at the primary side of the coils measure?

what do the tips of the fuel mixture screws look like? nice and sharp still?

have you checked for a broken off tip(s) in the carb body from yours, or a previous fuel mixture screw?

have you researched the correct clip position on the needle is supposed to be? is it the second or is it the third position?

 

[shinzon1]

the fuel screws are brand new i've checked them repeatedly. all the pilot holes are clear. no tips broken off. all parts and bodies were soaked for 3 days. blown threw all of them everything is clear. the bike has the mac 4 into 2 exhaust. stock air box. all orings have been replaced on the carbs as well as the intake boot rings. the intake boots themselves r still very flexible and seal tightly. i've sprayed carb cleaner around the boots while it was running and no change. so i don't think its a leak. mains are 102.5 which im sure are small, but ive never seen anything that it would affect at idle and while crusing with the throttle just barely open. pilots are 15. not sure on the needle numbers. i'm at work today, but i'll try and pull one real quick and find out. thanks!

 

[chuck hahn]

That all sounds real good.. except I think the Mains should be at least 110s or 115 and the pilots up to the 17.5s for a 4 into 1 setup. Then i would also set the clips in the center groove. The pilot screws at 1 out and the air screws at 1 1/2. That is the general conscensus as far as i have been to establish from all the teachings and tutorials i have read. If you want the jets i have there yours free..

 

[shinzon1]

the voltage is right at 12.5 volts when running. my seats do not have the screens. the only set of numbers i can find the needle on the slide is Y64. everyplace i've read says that the 17.5s are 9 times out of 10 too big? and the exhaust is a 4 into 2 not 4 into 1.

 

[chuck hahn]

I misread that its a MAC 4 into 2..MY BAD.

 

[rustybronco]

So rather than pulling the carbs and measuring 24mm or 26mm exactly and thinking they're right; the only way to really know what is happening with your fuel level, is by checking it with clear tubing - running from the drain screw hole in the bottom of the carb to the mating surface of the carb body with the float bowl.

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

idle is all over the place it might idle at 1500 or slowly start falling till it finally cuts out. it just kinda jumps all over the place.

This make me think you are having an issue with fuel levels and or flooding (too rich).

you need to externally see whats going on the the fuel levels when the idle drops.