I rebuilt a Yamaha YZF-R 125 a few weeks back for none runner, low compression.
Stripped it all down and only thing wrong was head gasket. Head and cylinder still perfectly flat.
When putting it back together I did think it was a pretty poor design and would be very easy to miss-fit the camchain on lower crank sprocket.
Well roll on a couple of weeks and I got a Yamaha WR-125 in (same engine).
Had had a major service and new timing chain fitted at another shop.
To me this looks like the timing chain was riding on the outside of the crank sprocket and eventually ground the teeth off?.
Customer is weighing up options, a new crank, piston and set of valves should make a decent engine again, valve guides look OK.
Stripped it all down and only thing wrong was head gasket. Head and cylinder still perfectly flat.
When putting it back together I did think it was a pretty poor design and would be very easy to miss-fit the camchain on lower crank sprocket.
Well roll on a couple of weeks and I got a Yamaha WR-125 in (same engine).
Had had a major service and new timing chain fitted at another shop.
To me this looks like the timing chain was riding on the outside of the crank sprocket and eventually ground the teeth off?.
Customer is weighing up options, a new crank, piston and set of valves should make a decent engine again, valve guides look OK.