**"Perplexed"**

dubbstepped1

New Member
Joined
Nov 7, 2018
Messages
24
Me, and my friend built him a motobike, we installed a fairly new head, and also a hi-performance carburator, My question is;
The bike fires up well enough, first try even, but the problem is max speed is approximately 8-12 miles an hour, also i noticed there was two sections on gas line, that was barley seeping, that one i put zip ties on, would that cause bike to have no power, i figure its probably the head or carb, but im unsure where to start, if someone could give me some advice, i'd really apreciate it................(here's some pic's/if they'll help/also**"the motor is an 80cc goplus motorized bicycle motor., "thank-you".......
 


gary55

Well-Known Member
Joined
Nov 27, 2012
Messages
3,463
if it's a stock head fairly new could mean warped. What is the compression, which carb is it, how much oil are you mixing? usually when it's that big of a dog it's a compression issue.
 

dubbstepped1

New Member
Joined
Nov 7, 2018
Messages
24
Me, and my friend built him a motobike, we installed a fairly new head, and also a hi-performance carburator, My question is;
The bike fires up well enough, first try even, but the problem is max speed is approximately 8-12 miles an hour, also i noticed there was two sections on gas line, that was barley seeping, that one i put zip ties on, would that cause bike to have no power, i figure its probably the head or carb, but im unsure where to start, if someone could give me some advice, i'd really apreciate it................(here's some pic's/if they'll help/also**"the motor is an 80cc goplus motorized bicycle motor., "thank-you".......
 

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gary55

Well-Known Member
Joined
Nov 27, 2012
Messages
3,463
The fuel line is not the prob. Those carbs tend to run rich so jetting to a smaller jet will probably be in the future, but it's not the issue for 8 to 12 mph. Can you do a compression test on it? Do you remember how far the plug extends into the chamber. Was it a complete engine when you got it or has it been pieced together? The reason I ask is the cylinder on your engine is a good cylinder, but it is made for a certain type of engine thar uses an A type piston. It's aprox. 1mm taller than those used in a B type engine and will cause low compression when used in the wrong application.
That is probably too much info, so lets start with a compression test.
 
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