Converting an ES 175/2 to 250

[John Tickell]

I see in the parts list that the ES175/250 crankshafts have different part numbers. By fitting a 250 top end onto a 175 will there be problems?

[Rob Holusza]

Engine will be out of balance vibrating badly so you need a 250 crank.

[John Tickell]

Thanks for reply. Since posting the question have bought the bike and paperwork shows a 250 crank purchased.
It still runs a 26mm carb but doubt if that will cause much of a restriction.

[Rob Holusza]

Jetting will be definitely too small. Was it rebored to 250 or it’s completely different top end?

[John Tickell]

Sadly I don’t have too much detail on this as its changed hands a number of times since converted. Will get it running first then look further if required.
An interesting project.

[Author]

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