My Big bear has always looked and ran just like it did when new. Always kept clean, garaged and babied but lately it is gone to heck and maybe somebody can tell me what to do.

It starts fine, idles good and runs great when it is cold. After it warms up, I can take choke all the way off and it runs fine. Good acceleration and power.

After riding it a while, especially on slow. hilly roads in the woods, it juist does not have any power.

It does not sputter, backfire or run rough. It just has no power when I push the accelerator and I have to go to a low gear to get up a hill. I can tell it is running hot and sometimes the fan comes on which rarely happens normally.

The only problem I ever had was the opposite when it acted like the choke was on and I had to remove the carb and clean all the jets and passages and it ran fine after that. That was 4-5 years ago.

I don't see anything obvious. New air filter, boots to the engine are secure.

I don't know what the problem is or where to look.

I appreciate any helo.

 

Today I checked valve adjustment and it was right on.

Unless I get a different direction to go I will get into the carb one day next week.

 

A rough check for a weak mixture is to give it a little choke when the symptoms occur, if power is restored you are running weak. Go through the carb, most likely there is dirt or water in it. Check the diaphragm and slide too.

 

Choke kills it completely. I am into the carb now. Thanks!

 

Could also be a blocked tap on the tank or filler cap vent. If the carb clean doesn't work, slacken the cap off when symptoms occur. If that doesn't work, check the flow of fuel from the tap. Electrical problems are possible, plug or coil being the most likely.