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View Full Version : no matter what i do bike wont rev above 2000rpm


frankiefrank
02-14-2014, 12:29 PM
I have a 150cc roketa. I have replaced as followed
cdi, coil, carb, cylinder, cylinder head, cam,air filter,jets etc.....
will not rev up and pipe gets glowing hot.
Ive checked for vacuum leaks up and down jetted cab.
installed after market pipe, air cleaner.
I bought the bike with 138 miles on it and they let it sit for 10 months yah
more like 5 years any have an idea other than setting it on fire

cheapeto
02-15-2014, 04:51 AM
Valve adjustment?

frankiefrank
02-15-2014, 01:14 PM
intake .oo4/ exhaust .005

carasdad
02-15-2014, 08:17 PM
I have a 150cc roketa. I have replaced as followed
cdi, coil, carb, cylinder, cylinder head, cam,air filter,jets etc.....
will not rev up and pipe gets glowing hot.
Ok..so you replaced all those items because it was getting glowing hot? Was it running the same before you did all that? First thing to remember when 'upgrading' anything.. ONE PIECE at a time..that way when you have problems..guess what it is? Exactly..it is the last part you put on..;) Otherwise who know what part it is and could be a combo the many parts you put on.
Anyway..running hot..not revving ..and glowing pipe is the #1 sign of an obstructed exhaust. If it sat that long the muffler may have a Bees nest..Mud Dauber nest..mouse house or other critters in it. Regardless it must be plugged. Now for the bad part. If the engine got so hot the muffler glowed or was even extremely hot so you could see it or smell it. The engine is most likely burned up by now..:ugh: Sad but true. If it was the CDI..it would not even start..if it was a too lean jet..it would still rev higher but get hot. If it were any of the other parts you replaced..it would either run..or not run at all...as they would not cause it to run hot. back in my day..the 70's and 80's..it was a common joke to shove a Potato in a person Car exhaust pipe. The car would run a few seconds..bog then shut down..or it would run super hot. What you describe is a picture perfect example of a plugged exhaust system. If the valves..intake or exhaust were set to tightly the engine would not even start..cause when too tight..they are partly open so no fuel gets in because there is no vacuum and there is also no compression stroke because with both or even one valve to tight..well ya get no compression. What does this all mean? Simple..an obstruction..:hmm:

carasdad
02-15-2014, 08:20 PM
Just noted..you say you used a different pipe. Ok..with all those new top end parts replaced..did you set the cam timing right? If not it may be getting a way to lean fuel/air charge. Also of importance..what is your compression?

frankiefrank
02-16-2014, 11:22 AM
compression is 150 psi.
cam is set at tdc (large hole up two small hole parallel with cylinder head)
I advance cam 1 tooth and bike went from 30 mph to 40 mph.
I am wondering if the flywheel marks are not right or pick up coil not set right.
new battery when first bought the bike it ran this way.

4getful2
02-17-2014, 11:37 AM
Verify that the piston is at top dead center and the crankshaft mark is correct, you may have a faulty flywheel key.
When setting the cam timing, you need to manually rotate the engine at least one revolution ,with the timing chain tensioner engaged and recheck the cam timing .