ATV Forum banner
1 - 5 of 5 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter · #1 ·
I was having some sputtering issues with my Big Bear 400, so I went through my usual steps. Replaced plug, cleaned air filter, pulled the carb and cleaned the jets. I was in a bit of a hurry and forgot to check/clean the float valve (the significance of this is about to become obvious).

Anyway, after my cleaning it ran great...until I hit an incline. When I accelerate on an incline, it stalls and will usually continue to sputter for a while. I could drive it for miles on flat land with no issues. It's only a problem on a hill (which is problematic, given that we ATV folks tend to encounter hills quite frequently).

What could be causing it to sputter only on incline? I'm going to pull the carb again and clean/check everything related to the float, but am wondering if anything else could be causing my problem.

Thanks.
 

·
Registered
Joined
·
522 Posts
On some of the Yamaha carbs there are 2 O rings under the float assembly. Make sure they're not split and fit snug into the carb body. If you replace them use Viton O rings. And check your float level.

Mad
 

·
Registered
Joined
·
2 Posts
Discussion Starter · #4 ·
Updating this for some future searcher's reference. After the aforementioned carb work that didn't work, I drained and completely flushed the fuel tank, replaced the petcock and gas tank cap (one without the auto shutoff bearings). Fixed and running great. Hard to tell which of the above did the trick, but I it's rolling. Thanks for the input.
 

·
Registered
Joined
·
140 Posts
Onya.

If the problem had been the fuel cap not allowing air in, the problem would have been time dependent, it wouldn't have shown up till you had drawn enough fuel to cause a vacuum in the tank, and cured itself when you loosened the cap to check you weren't running out.

Bad tap would seem to be it.

It's always best practice to do the simple checks first, which in a case like this is to check there is a good flow of fuel getting to the carby.
 
1 - 5 of 5 Posts
Top