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Ive got as Yamaha Big Bear that has trouble cranking especially in the cold. I can usually get it to crank if I partially cover the air intake hole under the seat cover and then it runs fine. I guess this is giving it a richer fuel mix to get it going. Any ideas on how to fix the problem? Could the choke need adjusting to give it more fuel mix? Thanks

Plug been changed lately? Depending on year they had a piece from the shut off valve that would break and get in the carb and cause probs. If that piece gets under the float it has trouble getting enough gas out of the pilot jet. I would try plug first and then take the bowl off the carb. Not real easy on some of these models.

I have a buddy with an older model BB that has a little black knob to the left side under the seat that has to be pulled out to get it to crank when cold. It has to run with that knob pulled out for a good 3 min or it will die. Check to see if you have one of these on your bike.

Basically needs to be primed sounds like?

It sounds like you doing the chokes job when you cover the intake. I would check and make sure the choke is working.

there is a vent tube running from the carb under the gas tank up to the handle bars {near the forks} make sure it is clear of mud/dirt.

judge jb

there is a vent tube running from the carb under the gas tank up to the handle bars {near the forks} make sure it is clear of mud/dirt.

Definitely take a look at this - I had discovered that problem two years ago. Seems like a dirt-dobber clogged the hose.

Also, how old is your fuel? I am now running "sea foam" in every tankfull to clear carb and as a fuel stabilizer.

FYI - I've got a 98 350 Big Bear.

Thanks for the suggestions. I have a new plug and new fuel. I will look for the vent tube and may try the sea foam cleaner.

buy a rubicon

2 things, first, this is a liquid choke can be stopped up or out of adjustment also there is a wire plugged into the bottom of the carb on the front edge next to the bowl this is the carb heater if it is bad or unpluged it will not run until the engine heats up

ewd506 wrote:buy a rubicon

buy a rubicon

thats a real helpful answer smart a@@. Why even post anything?
Sounds like SteveA knows his stuff. Thats probably a great place to start. It definately sounds like something with the choke system is not working.

I have a 400BB for 7 yrs now. I cut the gas off and let die before trlrng long way. Carry extra spark plugs on it for sure! Mine will foul one out in an eyeblink. Don't know why...was told I was running too rich/breather dirty It has fast idle lever for crankin. Runs fine; then all of sudden zip! to the plug.

I have a 99 foreman 400. If mine doesn't start on the first couple of tries I usually hit the primer a few times. It didn't want to run one night when we were going hog hunting so we started trying to figure out why. Ended up being a large dirt dobber nest in the breather tube that covered up a lot of the hole. We knocked it out and it ran like a scalded dog...

Again, I've got a '98 Yamaha Big Bear and she still runs like a champ. Rubicon that!