This is a GREAT quad!!! Bought new in '06 and never had a problem 'til now. Was sitting for about 2 years (but run about once/mo. for 10 to 20 mins.). Will not idle "off-choke". Starts on full choke, but when gradually reducing choke, engine just dies at a certain point. However, runs fine off choke with advanced throttle (higher RPMs). Have drained tank and added fresh fuel and fuel system cleaner (B-12 Chemtool). Also, replaced spark plug. BTW I have 900 hrs. on the engine and 450 miles on the quad. Any help appreciated. Thanx. Danno

 

You don't mention cleaning the carb out, you either have dirt or water in a jet. Clean the carb by blowing through the jets and passageways with compressed air. No rebuild kits, just air.

 

... thanx merryman. Having performed this "surgery" on my brother's Eiger, I was hoping to remedy the problem with just medicine (B-12 Chemtool fuel system cleaner). Do you think, over time, this chemical will breakdown the clogged jet so that the engine will run normally? Is there another way, aside from dissecting the carb to remedy this problem?

 

Carb cleaning is fairly easy. It is years since I did a Vinson, but on most, including the Eiger, remove the fuel pipe, you may need to take off the tank, slacken the carb intake and manifold clips, wriggle the carb out, remove breather. Then turn the carb on it's side, on some you have to take the choke cable out to do this, on some you can get away with leaving it connected. Once you can get at the four float bowl screws, take them out, a good fitting screwdriver is essential here. With the bowl removed, you take out the main jet and emulsion tube and blow it out, check by holding it to the light that it is clean, blow the hole it came from out and put it back. Repeat for the other jets. Check the float bowl for water, blow any dirt out and re-assemble.

 

... thanx. I've done a complete carb removal and dissection on my brother's Eiger about 3 years ago. I was hoping to not have to do this on my Vinson. Do you think, with time and use, the "chemtool" cleaner will dissolve the gum deposits and result in normal operation? Knowing a little bit about the symptoms, do you think the diaphragm may be damaged (torn or in someway compromised) and that may be preventing idling off-choke? Thank you.

 

If it is water it will either get worse as more gets through, or cure itself. Dirt is usually jammed in there and needs compressed air or a bit of wire to get it out. You may be lucky and it could clear as you drive. All sorts of symptoms are caused by a holed diaphragm, but yours sound like dirt in the slow running jet. If you do remove the diaphragm be warned, it took a week in the fresh air before the rubber had shrunk down small enough to put back, on an Eiger I checked last month.

 

... thanx, again. I'll give it a little more time before it goes "under the knife". But to be sure I'm understanding, the slow speed jet is accessed via the bowl removal and not under the "sealed plug" on the area of the carb where it connects to the intake port of the cylinder (the plug faces downward)... I drilled-out this "plug" and removed this needle valve on the Eiger, but I don't believe I ever got the adjustment right when I reassembled the carb. Are there any other jets besides these 2? //d

 

Not trying to hijack this thread,but there are several videos on the Vinson carb(if it's the right year model) on you tube that may be of help also.

 

Your pilot jet is clogged...that's why it will idle with choke on (adds more fuel), but not with it off...giving it throttle means you're moving off the pilot (idle) circuit and into the needle/main circuit.


These idle jets have tiny little holes...sometimes a carb cleaner (gas additive) can break it down, sometimes not.


I'd bite the bullet and pull/clean the carb...you will need more than just compressed air as that won't remove the shellac the old gas creates (yellow/green nasty stinky stuff). I use an ultrasonic cleaner - but a small wire brush and some carb/brake cleaner will also do the job...

 

... thanx, so much. 'Sorry for this late response. The videos are GREAT. Just this evening I performed the "carbectomy". Removed all jets, cleaned and blew out with compressed air. I'll stitch it up tomorrow. Expecting a good prognosis ... //d