by GuS » Sun May 14, 2017 6:38 pm
Patrick, Panman and Ambike.
Tanks a lot for you answers and help.
You're right about the smaller diameter, it was the top groove that lead me to believe the crown 1/2 way down to the top ring was narrower.
I will never be able to collect the parts needed to get an autentic bike. This not my intension. Plan is as said to get it on track to have fun, and along the way find out as much I can what i got, and assemble it to right specs. So far it has paid off, as the valve timing was completely wrong.
To the radius at the bottom. I see the K/KR pistons in Jerry Branchs engine presented in that article also are radiused at bottom.
The Harley competition racer booklet states 0.007" piston to cyl clearance. In my notes I have noted the Dow metal piston should have 0.016"
I learned from the late mr Steph at fhp board that themperature difference between piston/cyl was 100 deg celsius. Thus boiling a piston in water, then measure the change in size. Has helped me if I didnt know the piston manufacturers spec,and to check pistons befor I bore. I ignore that measurement once and bored for T&O pistons avcording to their specs.... They seized forst run...
Also if you measure the cyls before and after torqing to a stress plate, you will find that this alone will steal 0.001" ( reference is wl cyl with narrower base than th Ks) . But if you ensure correct torqe when boring/honing, can control mixture (not lean) and conrol the ignition timing, you may reduce the clearance and give the cyls a longer life. As a note i run Venolia (forged) with their specified 0.007 clearance in my wl stroker. They make a lot of noise before hot.
GuS