I'm not sure if this is where to post my dilemma.

My wife has a 2003 Yamaha Wolverine 350cc that has me stumped. The first time it started doing this was while out playing around on the trails. I've replaced the spark plugs and tore the carburetor apart and cleaned it, but it doesn't help.

What's odd is every once in a while it will run just fine. My son and I went camping and we took it with. My son rode around on it with no problems until the end of the second day when it started chugging again. We took it home and I left it alone until I worked on it Saturday:

* - Removed the carburetor and thoroughly cleaned it.
* - Removed the gas tank and cleaned it out.
* - Removed and cleaned the pet ****. Screen looked good but had some kind of deposits at the base of the pet ****.
* - Replaced/Changed the oil, oil filter, fuel filter, gas and spark plug.
* - Cleaned the air filter and resprayed it.

It starts up just fine, but when I give it gas it just chugs. If I try driving it in gear I can barely get it to crawl. I don't know what else to check for. Any clues?

 

Sounds like you are a victim of the infamous Yamaha parking brake switch,it keeps the engine from revving if the parking brake is left on,just sputters,but the switch goes bad a lot,and will cause it without the brake on. You should find a couple of black wires going to the left hand brake ,unplug them and see how it runs, I forget if you have to short them, or leave them open, and just tape the connector off, and just remember to check the parking brake before you take off, my 95 wolverine has no switch, and I have melted a caliper, warped a rotor, and burned a few brake pads in my day !!!

 

After I posted this I did some Googling and ran across a post here that had the exact same symptoms. Thank you for confirming this. We never uses the emergency brake lever so I think it would be safe to disable it. If this is the problem, my wife is going to be extremely excited. Seemed like the only time it ran well was when my wife was unable to ride for health reasons. It has been almost a year since she's been on it.

Y'know, I've been tinkering with this Wolverine for a long time, spent hours on it Saturday. I never knew these things had a rev limiter on them. I have a 2003 Yamaha Raptor. I'll have to check and see if it has one as well.