Carb Help

[ZacH_GrifF]

This doesn't directly relate to a three wheeler but I like this forum and there really isn't much difference. I have a 92 Yamaha Timberwolf that runs fine at WOT and just putting around but it revs way up at idle. And you have to throttle it a little while starting for it to catch. Oh and choke doesn't make a difference till you pull it almost all the way out then it revs real high. Could this possibly be a intake leak? Can anyone help?

[fallguy666]

Sounds like it could be an intake leak.get the child fixed first! Check the pilot circuit next.it may be clogged causing a lean condition at idle.I have two of these ATVs.they are awesome little putt around things

[ZacH_GrifF]

Thanks I'll squirt some ether around the intake and see if I changes rpm any. If nothing happens is their any other possible problems?

[fallguy666]

Could be valve adjustment.could be the throttle cable is binding.did it just start doing this?

[ZacH_GrifF]

Throttle cable is free. The valves are tapping pretty loudly. I got the bike from a friend. It didn't run when I got it. Long story short the rings were stuck to the piston and it had no compression. I got them free with some oil thrown in the cylinder. I went through the carb and cleaned it. It runs it just has the high revving idle.

[fallguy666]

Def check the valves.is the idle screw to far in?and def check for air leaks

[ZacH_GrifF]

Thanks I just went and adjusted the valves a few minutes ago will see what it does in the morning. I can't crank it at night due to a stupid noise ordinance. And I have the idle screw set at the stock setting one and a quarter turns.

[YTZ drew]

I second the air leak. Valves won't make it rev up, just cause a misfire if too tight (which isn't your issue if they're tapping), check for air leaks and make sure your carb is clean. Also, I have seen a worn out slide / carb body cause that issue, as well as the little rubber tip on Mikuni choke plungers not sealing. Does that carb have a plunger style choke or a butterfly in the air filter side of the carb?

[ZacH_GrifF]

It has the plunger/o-ring choke and no butterfly just slide.

[ZacH_GrifF]

Ok so I went out and did a little troubleshooting. I sprayed ether all over the carb and intake mating areas and where the intake meets the head still could not get it to change any in rpm. What it's doing is, I'll crank it and it'll idle fine then all of a sudden it revs up real high. It stays there for about a minute or two then it will idle back down to normal. It does this on and off.

[ZacH_GrifF]

Well I found the problem! The spark plug was loose in the head and I put a new o-ring on the choke plunger. I was taking the plug in and out trying to check for spark when I got it. I guess I forgot to tighten it after I left it finger tight. I don't know which one fixed my problem it might have been both but its fixed. So if some one is experiencing this problem and can't find the regular suspects (vacuum leak) check the spark plug and make sure its tight.

[DohcBikes]

It was likely the o-ring, not the plug.

[ZacH_GrifF]

Oh well thanks for clearing it up. I just figured it might be sucking air from around the plug. It was pretty loose.