My friend has a 650 vtwin and after about 5 minutes of running the atv will want to stall and is hard to restart. Also it try's to bogg down when you try to accelerate. I believe the carbs need rebuilding or the timing is off. He wants to sell the atv because he has sent it to two or three different places and one was a dealor and the atv still runs bad. The atv is In too good of shape for him to sell it.any advice guys? I would love to be able to help him keep this atv

 

If it is carburated, shouldn't be rocket science to go thru the carb.

Also check the tank and petcock for gunk. I had a honda 70 once (daughters) that kept plugging up and discovered the tank had black tar like stuff inside and came that way from the dealer because it had been sitting on the showroom floor a few years.

Check air filter.

Check breather hoses.

Oil level.

Battery good?

Spark plug wires/caps good? Maybe a plug cap is not getting contact with wire or the wire/coil connection is failing.

Now, if these easy checks are ok, maybe it is in the primary clutch. If the stock clutch has thousands of miles without maintenance, maybe check that. When you say hard to start, if the engine is lugging while turning over maybe the belt is not releasing all the way. Prob not the problem if you are in neutral while trying to start.

 

Does it start/run good for the first 5 min and then run bad? could be a stator/ignition problem, heating up can cause intermittant opens in stator windings or the cdi, causing it to miss/bog. See what the spark looks like when its cold, then run it until it starts to act up, then see if the spark has changed, like dimmer/weaker or yellowish instead of a bright blue spark. that would point to electrical issues. Running a few minutes then bogging could be a restriction in the fuel line, once the bowl runs out if it doesnt fill quickly enough it could cause problems, as MrSummit said, check the petcock screen for obstructions, probably best to pull the carbs yourself and check them out as well.

 

Thanks guys. I definitely think it's something small but I figured that the dealer would check on all of the things that u suggested.but I guess if you want something done right you have to do it your self

 

The symptom sounds like clogged pilot jets (2, since it has a twin carb).

Don't let anyone change/work on anything major components like stator, clutch, etc before trying something simple first.

 

Very true I will try that first when I see him.