ATV Forum banner

98 foreman loosing power

3K views 4 replies 2 participants last post by  SmokeyMcBong 
#1 ·
Here's the trouble hope someone can help, 98 foreman 450es after riding awhile the bike looses power. When this happens its sounds like air coming out of exhaust and it hardly has enough power to drive in 1st or 2nd gear, and there is no backfiring when this happens
 
#2 ·
any weird noises or difficulty running from the engine when you loose power? or does it just idle away perfectly but no power in gear?? does it rev up nice and smooth in N if you goose the throttle alittle? what about in gear, does it rev up or bog down when you experience the power loss??
 
#3 ·
When you would stop while this happens, the bike would idle fine and start up no problem. I tried it again and now it will run but stall after a couple of moment. After it stalls a Whooshing sound of air seems to be coming out if exhaust almost like there is build up of air being released after being trapped somewhere.
 
#5 ·
from the little info I have, my guess would be the valves or lifters. I'm not sure on the specifics of that motor but it sounds like one or more (again, not sure about that motor) of the valves not operating properly. The intake valve(s) seem to be working but the exhaust seems to be late. the exhaust gas trapped in the cylinder chokes out the motor and it shuts off. The woosh of air you hear could be the valve opening and letting the pressure off after the machine dies.

not sure if a compression test or cylinder leakdown test would show the building pressure or not. Again, I'm just kinda stabbing at it.

good luck
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top