What would cause an engine to bog half way up the rpm range?

mhornfeck72205

mhornfeck72205

New Member
#1
#1
Hi all. I'm still having problems with this engine of mine. Now it likes to entirely bog down and cut power when I hit about 4k and it sputters at that rpm until I let off and decelerate. If I start from a stand still the engine revs perfectly and sounds excellent until then. The plug reads a light tan so I'm doubting the mixture. I'm thinking possibly to clean the carb? What should I look to clean besides the jets? Could this be anything else besides the carb? Running 93 octane.

gx200 + arc rod, 18lb springs, flat top piston, milled .010", ported, 8deg flywheel advance, straight pipe, unifilter, stock carb (.036" main jet), gov removed.
 
mhornfeck72205

mhornfeck72205

New Member
#3
#3
yea it ran fine and then I had that problem of the jet being lean about 2 weeks ago after porting the head so I fixed that and it worked perfectly for a while. Going to go clean the carb in a little bit.
 
TT

TT

#4
#4
I am not an expert. However, the stock carb is running too lean and needs more fuel. The plug should be chocolate brown or darker and then lean it out later. I suggest drilling the main jet or going larger on the carb. You made lots of modifications and did not up the fuel and air mixture to the motor. Too lean will result in a hole in the top of the piston, richer is allways better, than too lean. Also, up the octane after the plug gets darker. It's not clogged, it's too darn lean..

I hope this is taken into account. All things considered, a black plug is better than a tan plug.....

TT :smile:
 
Last edited:
minibikedude

minibikedude

Active Member
#6
#6
Check your float leval, I just had this problem with a Tecumseh 3.5hp engine. That I put a new flloat in it and thought I eye ball it good enough for a 3.5hp engine. I would get up to speed good and then it would start to sputter, I would back off the gas and coast for a minute and it would take back off and do the same thing again. I had to readjust the float to let a little more fuel in, it was not open enough to let the fuel in while when running at full speed under a load.
 
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