new problem with motor someone help!

8

85pulsarnx

New Member
OK, here is the problem about a week ago i was riding my motor bike back from a friends and
all of a sudden the engine slows down and dies. I pedaled the rest of the way and tried starting
it when i got home it starts and runs just fine and rides perfect at about a quarter of the
throttle. As soon as i turn the throttle past a quarter it just slows down and dies.
please help. here are my motors specs:
80 cc from bikeberry.com
new carb
open exhaust =)
new spark plug
stock needle setting
Just a side note when I have the clutch in it throttles all the way to max rpm just fine.
Thanks in advance for all replies!
 
What do you mean by "open exhaust"? If it means what I think then that might be the start of your problems.
Tom
 
i own an 80cc (76cc)kit from bikeberry too haven't run into this problem, how tight is your chain? the only problem i have had was with the inner clutch spring came loose i tightened it good and everything was fine.
THis is a guess but when you try to start it does the motor sound like it is trying to start or only sometimes, and do you get a lot of drag like your pulling a heavy load and no compression. those are the symptoms i had and it turned out to be the inner clutch spring.

when you open up the throttle your putting more stress on the friction plate and causing your gears to slip then it dies.
 
when you say new carb . did you just put it on . if that's new then it probably needs to be adjusted , when you open the throttle and it has slow pickup that's normally too lean . then while running lean your motor will run too hot . and eventually not run till the motor cools . another sign of carb needing adjustment is at full throttle if you let off the throttle a little and your bike picks up speed . that is a lean mixture . you may also have an intake leak . try fiddling with the mixture screw if adjusting it really doesnt change anything its probably an air leak somewhere in the system .
 
Last edited by a moderator:
Check for oily residue between the head and the cylinder. It sounds like your losing compression. Check the plug too. You may need to re-torque the head bolts. Also like always do the wd-40 leak tests.
 
Thank you for the advice I tried a new plug,recapped exhaust.
The carb does not come with a mixture adjust knob.
I will try different needle settings today.
I removed the cylinder head all looked good
I will mention again that it runs great until I hit 1/4 throttle
and when the clutch is in it revs up all the way perfect.
 
do not remove end cap two stroke engines run off back pressure youll burn up your rings real quick then its all down hill i would say check your rings
 
85pulsarnx said:
Thank you for the advice I tried a new plug,recapped exhaust.
The carb does not come with a mixture adjust knob.
I will try different needle settings today.
I removed the cylinder head all looked good
I will mention again that it runs great until I hit 1/4 throttle
and when the clutch is in it revs up all the way perfect.
Click to expand...
Did you remove the float bowl from the carb and

check that the jet is screwed tightly in?


When you removed the cylinder head did you loosen the barrel and
break the seal at the base gasket?
 
OK I am getting extremely angered at this engine.
I pulled the whole thing apart and everything is just as it was when it was new.
I think i am just going to get a new engine.
 
Hey guys, second build here any my engine seems very weak, i started it up and goes but noting like my other bike does, its almost like it governed, is this to do it being new? I dont remember this problem with my first build? Im mixing 16:1, the bike runs fine just sounds and is weak at wot it feels like a 49cc but almost restricted a bit? any suggestions?
 
You beat me to it.

Dirt and junk enter my carb somehow.
I have both a fuel and air filter.
The jet gets clogged with junk , and will not allow the proper flow of fuel.
When my bike seems to die at 1/4 throttle .
I clean the jet.
 
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