Hi Guys, advice needed!
My Yamaha Big Bear 350 quad had a problem last year flooding and filling the crankcase and airbox with fuel. The carb was overhauled, all new parts etc and everything ok until now, the new problem is a bit strange:
With the fuel tap turned OFF, the engine will run at idle until the fuel in the bowl is used, the engine will not accelerate above idle, if the fuel tap is turned ON before the engine uses the available fuel and dies, the engine stops running! The spark plug is sooty and there is a small amount of fuel in the airbox, am I right in thinking that the problem with the float has reappeared or could it be a blocked jet? There is no contamination in the fuel. Any advice would be appreciated.

 

Sounds like what happens if the float is sticking or float level is off. Plus I'd make sure the jets from the rebuild kit match what the ones from your old carb had. Some kits,jets are different. Sooty plugs are because it's too rich somewhere. Plus the pilot screw(fuel screw) adjustment may be to rich at an idle.

 

Thanks, just what I thought, unfortunately, dissapointed that the carb kit I fitted has only lasted 14 months. All was fine when I fit the kit, so presume the supplied jets etc were right.
Thanks again for the advice.

 

i had a 99 big bear. the carb was junk. i just had it replaced and it ran like a top.

 

I guess you are right! Do you know which carb you used to replace the old one?

 

Just look on ebay,several listed that might work on your model.yamaha Big Bear 350 carb | eBay

 

You are exactly right! Just bought one from eBay, thanks

 

i think it was a 33mm mikuni. just did the same thing to my yam timberwolf a couple of months back. damn yamaha like those things..............a new one was about 250 bucks.

my little 250 screams. Wiseco .5 over piston, new head, new carb, new stator, new cam chain and guides with a new DG exhaust pipe. its scary fast for a 250.

 

Thanks for the information, hope the new carb sorts the problem.

 

Hi guys, more advice please, got new carb fitted but still got exactly same problem, anyone any other ideas, maybe not the carb after all??? What else could it be?