Will a Yamaha QT50 engine fit a PW50?

[wylie]

I have a 1985 PW50 with blown crankcase seals & a scored cylinder. I was ready to part the thing out but a friend told me that an older QT50 moped engine (found cheap on ebay) is exactly the same and would slip right into the PW using the same driveshaft, carb, coil, etc. Has anyone successfully completed this? I'd hate to buy the engine then have bolt patterns not line up and have to do a lot of unpleasant cutting and hacking for something with such little resale value. Any opinions are appreciated. Thanks in advance.

 

[Jasle]

The motor is pretty much the same thing. The drive shaft on the QT is longer, the pipe is different but the pw pipe will fit. The biggest problem is the right hand side swingarm. The QT does not have one. You have to make a zig zag bracket to hold the swingarm on the right side.

For the cost I'd suggest just replacing the crank seals and either boring to an overbore or getting a new cylinder. Cylinders are in the $120 range and you could have fun and use a yamaha YT 60 piston and overbore your cylinder to get a 60cc pw50.
The gearing from the rear of the QT is better for takeoff but the shaft going through the center of the pinion gear is too short for the pw50 so you need to press it out and use the pw50 one.

 

[aus426]

You can use the complete YT60 top end, as both bikes share the same base gasket.

 

[wylie]

Thanks for the info. I saw a couple QT50 motors on ebay starting at $49.99 and was tempted as being a low buck easy way out. As long as my kids are going to be the riders, your suggestions would provide a much more sano solution. I'd rather have the stock swingarm setup rather than a "value engineered" patch just to fit the moped engine.

 

[Jasle]

Aus 426 is right. the entire topend off the yt 60 drops right on. Then added with the fmf pipe its flat crazy. Not a cobra beater but it smokes. its just hard finding them.