Carb Help!!!!

[poolie]

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I own a 1984 VF500 Interceptor. It won't idle. Have adjusted pilot screws to factory settings which made no difference, I then adjusted the screw at the front of the carbs which I took to be the idle speed screw, when I did this could get the bike to idle at just over 1000 revs but when the I rev the bike it goes up but when released it hits 3000 revs and very very slowly drops, under these circumstances bike smokes (white smoke).

Without any idle it runs well when I ride it.

Any thoughts would be greatly appreciated.

[squirrelman]

has it been sitting for awhile??
run some Sea Foam through it and report back.........

[GreyVF750F]

White smoke indicates antifreeze/water in combustion chamber. Possible bad fuel, water in the fuel? Drain your tank and put some known good fuel in it. Do a compression test and a coolant pressure test. Then get back to us.

[masonv45]

Slow return to idle is classic symptom of a carb sync needed - or a binding throttle cable.

[poolie]

Hi,
tried the seafoam but everything still the same. The throttle slowly drops from 3000 revs only after I've wound the idle screw in to produce an idle. If I wind it back out so there is no idle then there is no delay in the rev counter drop, it also seems to smoke more when I wind the idle screw in.
Do you think I may be looking at a head gasket or something worse????

Thanks,

Poolie

[GreyVF750F]

The slow return to idle could also indicate a vacuum leak. Tighten the clamps that secure the rubber manifolds to the carbs and head. They are know to leak after many years of use. Like I said before in order to find out if a head gasket is bad you need to do the compression and pressure tests.

[poolie]

Did a compression test, one piston is 50% down on the others, is there any other possibility but head gasket or cracked head?

As always, thanks for any advice.

Poolie

[masonv45]

Not with the white smoke out the exhaust.

If it's a valve, head gasket, or head crack issue, you're going to have to take the head off anyway.