1982 GS650e - 342 or 420 Cam Sprocket

[KillerGriller]

I bought a used head to replace the existing one on my 1982 GS650e, pulled everything apart and compared the pieces. Everything looks good with the exception of the cam sprockets; the previous sprockets are smaller than new ones, and stamped with 342 (new) vs 470 (old).

any suggestions on what I’m looking at? Advantages/disadvantages to either?

[KillerGriller]

*Edit - the new cam sprocket says 470, not 420 (maybe it was starting the weekend early?)

After doing some digging on the web, I think the 342 sprockets are from an 1100? Would there be any benefits to running smaller cam sprockets?

[Grimly]

*Edit - the new cam sprocket says 470, not 420 (maybe it was starting the weekend early?)

After doing some digging on the web, I think the 342 sprockets are from an 1100? Would there be any benefits to running smaller cam sprockets?

No can do, as the gear on the crankshaft is fixed for life. The cam sprockets must match it in the normal ratio.

[KillerGriller]

Cheers, thought so, but it’s always safer to ask first.

Any chance an 1100 crank would fit in a 650 bottom end? (if not it would save me pulling it apart to check)