what kind of engine do I have? Size and Manufacturer?

Sandvader

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Jun 23, 2021
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I'm trying to help young man who is likes getting his hands dirty. He found this bike with a motor kit and the motor is seized up. There is nothing on the motor that I can see that tells me what it is. I've never worked on motor like this, but I have enough knowledge to try to help him. I've attached a picture.
IMG_4926.jpg
 

Greg58

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May 1, 2011
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That looks to be a 48cc, manufacturer doesn't really matter because parts are interchangeable. If you take the head off you can measure the bore, if it's 40mm it's a 48cc, if it's 47mm it's a 66cc or 69cc depending on the stroke. The 66cc is 47mm x 38mm, the 69cc is 47mm x 40mm.
 

Sandvader

New Member
Jun 23, 2021
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That looks to be a 48cc, manufacturer doesn't really matter because parts are interchangeable. If you take the head off you can measure the bore, if it's 40mm it's a 48cc, if it's 47mm it's a 66cc or 69cc depending on the stroke. The 66cc is 47mm x 38mm, the 69cc is 47mm x 40mm.
You hit the nail on the head! It is 48cc. Thank you! We got the engine tore down to the piston and bore. They both look ok. Engine still won't turn. So our next step is to take off the clutch and then probably take a look at the crank shaft. Everything on this bike is rusted. The rear hub is locked up, the carburetor was filled with rust, part of the shut off valve broke off in the gas tank, the throttle won't turn, tires are sun rotted out. However the front wheel spins nice! lol It will be a good project for that kid to tear it all down and then put it back together.
 

Greg58

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May 1, 2011
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Before opening the case remove the drive chain and try to rotate the transmission with a pry bar or screwdriver, it’s only a through shaft with a spring and two bearings.
 

Larry Trotter

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Nov 26, 2017
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Before opening the case remove the drive chain and try to rotate the transmission with a pry bar or screwdriver, it’s only a through shaft with a spring and two bearings.
If the shaft is locked he won’t be able to remove the chain.
 

Larry Trotter

Active Member
Nov 26, 2017
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All the ones I have the chain won’t cleAr the case over the sprocket to remove it that way. If you put a 9 tooth on it the chain will clear.