Re: Back on Trac

J o h n /
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SO! The trac jug seems to be very closely based on the Yamaha qt50/pw50/ five or six other bikes’ jug. The biggest problem with using the Yamaha parts is the wrist pin. See, the needle bearing for the trac’s wrist pin is 12x16x13 and the Yamaha one is 10x14x13. So three options. Use the stock piston with new rings in the Yamaha jug, ream the Yamaha wrist pin hole to 12mm and use the original wrist pin, or get one of THESE I’m betting on that last one being the best option. The stock piston and bore are in real nice shape still so I’m gonna keep using them for a bit, but in the name of… science? Posterity? Wheelies? Whatever. Hoping I can get a 70cc kit for a Yamaha to fit is the end goal eventually. Also I lied about the seals. Sorry. I have the specs I’m just lazy.

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