johnboy812

i have a force .28,and when i try to turn it over it sometimes makes a sound like the the piston is hitting the head.it isn't quite broke in yet and i was wondering if its normal and if not what would cause this.i would really like some advise before i take it apart.

Losi-Runner

If the engine is brand new and you haven't taken it apart yet then most likely it's just the tight pinch from the piston and sleeve fitting. The sleeve is taper so that is why you are getting alot of resistance when trying to turn the engine over. If this is a used engine then you might wana take the cooling head off and make sure you have the correct amount of head shim(s).

mamba4life

iTrader: (31)

get a powerhouse preheater or use a heat gun before you run it! that should stop the problem IF you have the rite shims

johnboy812

thanks guys,i was wondering about the shims myself.how many should there be.the engine is makes a (ting) sound when you turn it over but if done slowly it doesnt

toobad4u

iTrader: (93)

Is this motor a pullstart, drill start, or bump box setup. I had a .26 Force that was a pull start, and it would make a similar noise because the pin that cought the back of the crank wouldn't go in all the way and slip sometimes.

Good luck,
Stephen

kevinmajor

iTrader: (3)

Adding shims basically retards the timing. 30% nitro has a higher flash point over 20% nitro fuel so you have to retard timing to prevent detonation.

Read your instructions on head shimming with different nitro percentages.

tc5 man

well i had a force .26 pain in the butt to tune

Frank L

iTrader: (148)

Always always always pre-heat the engine to 180 or so before you start it makes it last longer and much easier on the all the internal parts.

johnboy812

well i took apart the engine and found out it was the rod.it had enough play to let the piston move up a tiny extra bit and make contact with the head.other than that everything looked good,so im gonna put in a new rod and see what happens. thanks for the help