Engine Trouble Bike wont go faster than 24mph with 36t sprocket

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I would hate to think your particular motor was that weak but if everything checks out that might be the case.

A compression check can determine quite a bit...get a compression gauge or have a shop check it for you...if you have like 100psi with everything ok then thats all youre probably gonna get from it in my opinion without more mods done to it
 
Damn. I wouldnt be surprised. Well maybe i should be 100% honest. I bought this bike second hand. When i bought it the piston and cylinder looked in good shape and the spark plug looked lean to be honest. But i dint think anything of it tho. The lean part that is. it has torque but perhaps maybe do to possible low compression from being lean for long from the previous owner. Could that be the problem?
 
Well yea thats possible...running lean will burn a motor up but usually it either blows up or makes it out alive.

I have nothing more to suggest without knowing the compression number.

I dont know what the compression range your motor is supposed to have to be honest..i know the more powerful motors should be around 150 and above...My particular motor should read around 170psi.
 
A new motor should be broken in fairly rich...its possible the rings and cylinder was over heated and maybe warped...Again,a compression test can tell a big story about the motors health
 
My phone battery is about dead so if i dont respond for a bit i will when i get charged back up...be back later.
 
Sorry for all the questions. But lets say the compression # is lower, what could possibly be done to fix that?
 
Depends on why it is low.

If its low due to improper break in or ring seal then you need a new top end for the motor.

If its just low in general meaning not a very powerful motor (assuming the rings and cylinder are ok) then you can raise the compression by sanding down the cylinder head 1mm or so to gain power.

But dont sand on anything till you know whats going with compression...buy a compression gauge.
 
Sorry for all the questions. But lets say the compression # is lower, what could possibly be done to fix that?
I've read the thread from the start and dont think you have compression issues because you say that it has torque I think when you put the #64 jet in the plug shows rich in the bottom end and lean on top,The previous plug with the #70 jet was just all out rich, As 6blueoval9 said work your way down from the #70 jet a 67-68 will probably be right.Unfortunatly your top end is being held back by both the gear and the pipe,The gear just puts more load on initaily so if your engine is turning it up to 24mph thats 4,500 rpm and since you have no tunned pipe(expansion chamber) it's all up to the engine to make the power to overcome the gearing and then the stock exhaust is not letting it breath,You can look up on the site how to mod the stock exhaust for some improvement but you should concider getting a good pipe.
 
It looked lean to me in the first picture with the gray ashy color, and even leaner in the second pic. If its rich it's going to be oily and black not dry and gray.
 
It looked lean to me in the first picture with the gray ashy color, and even leaner in the second pic. If its rich it's going to be oily and black not dry and gray.
You could be right brother it's just deceiving in the pic with oil around the base of insulator and the threaded edge those carb's do tend to be pretty fat on the bottom witch would read like that then the whole insulator being coloured like that makes me think it's set up lean in the middle on the needle.
 
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