First; I just rebuilt the top end of my 00" Foreman and i noticed that the unit was getting pretty warm and the fan wouldn't turn on. I have been "Dealing" with this for some time. For a while the temperature light would come on but the fan wouldn't run. I have had the fan run before so I know it isn't dead. The bearings are ok because I can still spin it relatively easy by hand.


Second; When I start to rev the motor there seems to be a dead spot if I move the throttle too fast. Most of the time I can still rev slowly up without any problems. My friend thinks that I am running too lean, but I still back fire from time to time. What should I be looking for?

 

off hand it sounds like a lean condition........the dead spot and the hot engine are two symptoms of that but it could be other things too......

 

Even if I still am backfiring it could still be lean? My spark pulg also looks pretty dark (Can't really go off of that, I am running a lot of oil in my gas).

 

i would agree with ss97, sounds lean. a backfire in decelleration means your lean. and if its overheating faster than the fan/oil cooler can heat up, that would support running too lean.

i would richen your pilot jet. its located outside the bowl on the carb, twords the engine. small brass skrew. turn it out about 1/2 turn at a time in your case. im guessing you overborad the cylinder? i would also buy a jet kit; and upgrade your main jet size.

as for the "empty" or flat spot on your throttle; you can try moveing the clip down a noch or 2 on the needle. this will improve your mid-range and throttle responce.

 

I will have to try and adjust it, but I didn't bore the cylinder. Everything is as stock as she can be.

 

hmm, have you changed the compression or timeing at all? any why are you running oil in your gas anyway? theres no bennifit to that

 

I was told by a few other people to run some oil in the first half tank of gas after I replaced my pistion rings.

 

thats kind of odd. never heard of that. doesnt really sound like it will help anything, exept make your engine run hotter. after you get it running/idoling better then i highly recommend following this break in procedure. even if you just put in a new piston.

http://www.mototuneusa.com/break_in_serets.com


are you running 2stroke oil in the gas? that will also make it run too hot

 

I have never heard of anything like that either...... what purpose would running oil in the gas do? I would think it would do nothing but clog the jets and gum up the works....

 

It would also likely make it run leaner, since the oil won't burn as well...

I think I'd put some fresh gas in it. I wonder if the temp sensor might be bad as well, if the fan runs but not consistantly...

It might also be worthwhile to blow out all the carb passages. Possibly one circuit is somewhat clogged.