From:Doug Miller Electronic:radarsprint -A-
Subject:RE: RE: Piston size? Date:Tue Dec 27 20:06:10 2011
Response to:16725
Joe, I agree with what Dave says. I would further suggest that to re-piston the bike after it is built, runs and shows signs of excess piston clearance (a specific kind of knock) would be little problem.

The service manual will tell you many things about reassembly, somethings are not assembled in the easiest, most obvious way.



Why do you think you need a piston?

Is the engine in pieces or just the rest of the bike? I wouldn't replace the piston/rings as "preventive maintenance" unless there's a problem.

The desired piston-to-cylinder clearance is .0045" Accurate measurement of the cylinder bore and piston will require some $$$ tools that you will probably only use once. It'd be cheaper to take the cylinder and piston to an automotive machine shop and let them measure it.

The Service Manual tells you how/where to measure the cylinder and piston. Harley-Davidson sells a combined parts and service manual ("1958-1966 American-Made Lightweights - Parts/Service/Colors/Accessories" Part# 99444-93 for $40 - click on our Parts section, then see under Harley-Davidson). Good investment.

Measure the cylinder bore from the top of the cylinder about 1/4" above the exhaust port - measuring from front to back. Measure the piston at the extreme bottom of the skirt, again from front to back. The difference should not exceed .007"

Since the bike is apart, you should "de-carbonize" the cylinder ports and muffler (recommended every 5000 miles). The service manual describes how to do this. Carbon buildup will cause a loss of power.


Happy Holidays to Everyone,

I love this site. I bought a "60" super in pieces back in June. this is my first
restoration for this kind of bike. My speedo says it has over 16K miles so I am
thinking the 165 cc piston might be a thing of the past. What is the cheapest
and or easiest way to measure the cylinder. What tools would i need? Unless it
is inexpensive i would rather not have to go to a shop to find out.

Keep up the sharing of all the wonderful information.

joe in NH