power in low end, barely runs after warm up

chancecube

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Mar 18, 2011
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I can start my bike while barely moving, light pedaling. Before my bike warms up it runs great, all the way up to 27mph. After it warms up, getting any pull out of the motor while under 18-20mph is rare, mostly A lot of bucking and and cutting off. If i can keep the bike above 20 and under 27 at all times it turns out to be a good ride. Cant go over 27 because of 4 stoking which should mostly go away after break in. I had a over heat problem earlier which was due from too much oil mix. 16:1
The motor is a 66cc gt-5.
83 miles ago I replaced the rings and piston.
44 tooth sprocket and in NT carb
 
If it's four stroking, it's running too fat.
No two ways abt it.
Lean it out some and see what happens.
It will improve, or it won't.

Two strokes are notorious for running crappy when cold, and running like a madman once they are good and warm.

If yours does not do that, your fuel/air mix is wrong.

rc
 
the cylinder wall did have a scratch

that means its siezed. even if its what some people call a soft sieze. a new ring can make the scratches worse. take the top end apart and see if the scratches are worse. you very well might have to replace the jug and get another piston/ring.
 
that means its siezed. even if its what some people call a soft sieze. a new ring can make the scratches worse. take the top end apart and see if the scratches are worse. you very well might have to replace the jug and get another piston/ring.

I'd like to disagree with that, T...

Now that we have a scratch to consider, we need to figger how it got there.
Could be from build-up of combustion chamber debris, (carbon fouling), a broken ring, chunk of a piston, chunk coming in through the intake, or internal engine parts from a casting flaw.

Many years back I lost a cable end from the carb slide and it buggered up the piston crown and cylinder head. Could have just as easily lodged in a place to score the cylinder wall.

...So tell us more about this scratch!
Is it there now? or was it there when the last rebuild was done ?

Do you run an air cleaner??? :)

Best
rc
 
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