Identifying an engine

surferscha

New Member
Jun 25, 2013
2
0
0
florida
I recently swapped out a motor on my friends motorized bike because his motor needs a top end (cylinder, piston and rings). I want to rebuild the engine but my friend does not know whether it is a 49 cc or 68 cc. Is thier any way to tell by measureing the bore or whatever? Or are the cylinder and piston kits interchangeable for the 49 cc and 68 cc?
 

bigbutterbean

Active Member
Jan 31, 2011
2,417
2
38
Lebanon, PA
Is it possible to compare it to an engine that you do know the displacement of? Even on the outside, a 66cc cylinder looks bigger than a 49cc. If you put it beside an engine you do know the size of, you may be able to tell by looking if it is the same or different from the other engine.
 

MotorBicycleRacing

Well-Known Member
Jul 28, 2010
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SoCal Baby!!!
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I recently swapped out a motor on my friends motorized bike because his motor needs a top end (cylinder, piston and rings). I want to rebuild the engine but my friend does not know whether it is a 49 cc or 68 cc. Is thier any way to tell by measureing the bore or whatever? Or are the cylinder and piston kits interchangeable for the 49 cc and 68 cc?
Welcome to the forum. :)

The 50 cc and 66 cc / 80 are not interchangeable.

It's easy to tell the difference if the motor is apart.

There are slightly different motors though so the replacement piston and cylinder have to be the same.

This pic will help you figure it out with a little measuring.

 

surferscha

New Member
Jun 25, 2013
2
0
0
florida
thanx. MBR. I have 47 mm bore and 8 mm studs. With your info has to be a 66 cc. Dude, motor bike racing! so cool. want to start a racing club here in florida. gas powered bmx, gas powered road raceing and oval. any info on how to get it started?
 

MotorBicycleRacing

Well-Known Member
Jul 28, 2010
5,845
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SoCal Baby!!!
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thanx. MBR. Dude, motor bike racing! so cool. want to start a racing club here in florida. gas powered bmx, gas powered road raceing and oval. any info on how to get it started?
Yes, I have a lot of info on how to start motorized bicycle racing in your area.

Sorry, I don't have the time to do it right now in detail.

First find race venues near you that will let motorized bikes race
for a reasonable price.

Then get back to me when you have that done.......... :)