Topic: CB650 pistons in a 550?

[purf_man]

So I have a pile of leftover parts from my hybred motor build.

I was looking to put together the 650 cases with the 550 top end but would like to pick up the extra compression and larger bore.  Can the pistons be trimmed down enough on the domes to work?  I have the stock 550 pistons and sleeves I can run in it but was wondering if I could pick up a little on this "leftovers" build (it is getting the 650 cam as I am going with a regrind on the 550 to retain the 550 tach drive and match my 740cc better)

[trueblue]

I would be surprised if there is enough meat in the top of the piston to cut away to allow it to go into the 550 head and still keep the crowns attached to the skirts.  The combustion chamber of the 550 is a lot smaller than that of the 650.  If you want to do this you will probably need to use the 650 head or massively reshape the chambers of the 550 head.

[purf_man]

Well my 650 head is ending up on my stroker motor.

I guess I will toss the 550 sleeves back in the jug and order up some new rings.