engine problem

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.
Check and make sure when you give it full throttle that the throttle servo is actually opening the carb all the way. Maybe your throttle trims got out of whack.
 
could be a number of things /pipe too restrictive/ air cleaner too restrictive/throttle plate adjustment,but it should rev higher than that at 1/4 throttle/way too rich/no fuel tank vent ,this mostly only causes problems after a few min of running/engine timing ,did the key drop out when installing the flywheel/coil failure ,rare but possible/spark plug gap ,too large will retard timing /poor fuel/coil air gap,to large will retard timing/kill switch/ then you have all the internal mechanical possibilities ,transfer port to crankcase alignment,I have seen the base gasket installed backwards blocking the ports/compression too high, will lower RPM/poor compression,would be hard to start /crankshaft out of faze ,causes vibration and a huge loss of power/crankcase air leaks , mostly causes poor Idle / a bad carb ,try a different one if you have one.

cheers Roger
 
thank you i have tried everything i switched carbs the pipe always worked good the engine ran good when i put it away last year i even ran it without the airfilter no change i am going to tear it down and check it out
 
RAMJET said:
could be a number of things /pipe too restrictive/ air cleaner too restrictive/throttle plate adjustment,but it should rev higher than that at 1/4 throttle/way too rich/no fuel tank vent ,this mostly only causes problems after a few min of running/engine timing ,did the key drop out when installing the flywheel/coil failure ,rare but possible/spark plug gap ,too large will retard timing /poor fuel/coil air gap,to large will retard timing/kill switch/ then you have all the internal mechanical possibilities ,transfer port to crankcase alignment,I have seen the base gasket installed backwards blocking the ports/compression too high, will lower RPM/poor compression,would be hard to start /crankshaft out of faze ,causes vibration and a huge loss of power/crankcase air leaks , mostly causes poor Idle / a bad carb ,try a different one if you have one.cheers Roger
Click to expand...
very helpful thank you.i noticed that there is alot of in and out play on the crank i would say almost a 1/8' inch no leaks around nothing though
 
side to side play should not be a problem in it's self .if you have checked everything else you may want to take a close look at the crank faze, what happens sometimes when changing or replacing the clutch if you were to hold the flywheel to loosen or tighten the clutch(reason you should always use a piston stopper ) you can twist the crank (crank cheeks can slip on the lower rod pin)what happens then is the piston binds slightly when traveling up and down the bore and the crank output shafts (clutch and flywheel rotate off center )it does not take much and it kills the power of the motor.

another thought ,did you upgrade the motor with a stroker crank, if so make sure the port timing is ok, be sure the exhaust port is closed when the piston is at TDC there should be no gap under the piston skirt. some guys have removed the base gasket in an attempt to raise compression(or used the wrong gasket ) ,in some cases this causes the fore mentioned problem with the port timing.back pressure from the exhaust will then contaminate the incoming fuel charge under the piston limiting the higher rpms .

could there be something blocking the exhaust , I had mud wasps make a nest in my weed wacker exhaust once,scratched my head for a while on that one LOL.

I thought this info may be valuable to someone . sorry for the poor grammar i'm a mechanic not a English teacher LOL.Roger
 
Last edited by a moderator:
Back
Top