Well isn't that cool!  I have never seen a brand new cylinder - only well used ones!

It will be interesting to see how much difference it makes - and what kind of wear patterns are on the piston/cylinder you remove.

FinnHammer wrote on 07/04/24 at 12:44:31:


Well dang!  I have a few rainy days here, and I have decided to pull my 95mm Wiseco DR650 piston out and try the 94mm Flat Top.  I was curious what kind of clearance you had.......I will go back into this thread and see if you listed it earler.

My cylinder was not too bad, and I can get a 0.003" feeler gauge in with a bit of coaxing (it doesn't just drop right through) - I cannot get a 0.004" feeler gauge in.

Finn, the clearance you recorded previously seems OK to me, but you never can tell.  It will be very interesting to see what sort of clearance you end up with.  A brand-new OEM cylinder matched with a new Wiseco forged piston, I don't think that combination has been tried yet.  Let us know what you end up with.

This noise seems to have you worried.  Not having the benefit of actually hearing the noise, I can only speculate.  But your clearance recorded previously was not unreasonable.  However, you did report that you massaged the top of the cylinder vigorously with a 160 grit.  I don't think your previous readings reflect that area.  The new OEM cylinder should be straight as an arrow, and the new Wiseco piston should fit in there nicely.  If anything, you will need to be concerned about too little clearance.  Quick & dirty checks with a .0025" feeler gage will be in order.

As I recall, you did some unorthodox stuff when you set up your 13-plate clutch, and you also converted to the overdrive oil pump gears.  Is there any chance that the offending noise is coming from the clutch or the oil pump drive?