TY175 engine number starting with 487

[Julz]

Hi

I have just purchased a 1976 TY175, but the engine number does not match the frame number. Frame number correctly starts with 525, but engine number starts with 487. Can anyone tell me what the engine is out of? It says 171cc on the barrel so it seems like the right displacement.

Cheers
Julz

[TriCub]

You should post a photo of the engine showing barrel and head, the TY experts could then tell you if it is correct.
According to the Yamaha model ID book that I have the 487 is listed as a 1974 DT125FA(B).
I know that the TY250's had funny numbers but I'm not sure about the 175's.

[David Lahey]

Would be useful for ID to have side views of both sides of the motor.
Having a 487 prefix just means that the right-hand crankcase half is from an early DT175 (many parts are interchangable between DT,YZ,TY and MX 125 and 175 motors)

[Julz]

Thanks for the responses. I have been advised that the engine number (or at least the crankcase cover) comes from a 74 DT 125. I need to work out whether the gearing is DT or TY. I am hoping TY because they have closer spaced ratio's in the lower gears.

[David Lahey]

I would be more worried about the left side crankcase half because the DT crank half has a completely different flywheel housing that the bigger TY175 magneto flywheel will not fit into - and the flywheel cover from the TY175 will not fit on a DT crankcase half. Again I suggest you post photos if you want help with identification of the motor parts.