Hello,
This is my first post to see if I might get the benefit of the collective wisdom here while in the process of topping a KHK. I'm retired from the aviation business and now spend much of my time fussing with old bikes in my friend's shop. He also is retired from the AvBiz and tinkers with vintage bikes and cars. I've mostly owned and worked on Guzzi, Ducati (Bevel), Triumph and a smattering of other sundry bikes, but this is the first Harley that's come across the transom. In ages past I worked at a Harley shop north of Atlanta where Clete Borchert was the service manager if he's familiar to some here as the "Old Dude" in Old Dude Motorcycles.
Anyway, I pulled the top end apart for smoking and plug fowling problems and found that the rings are shot and the pistons (.070: O.S.), though in reasonable shape, had a bore clearance of about .005" which I take to be rather over limits per the manual that the bike owner provided. I noticed that the cylinders had aluminum spacers that you can see below leading me to wonder if they are actually K Model cylinders spaced up to the appropriate KHK height. Common practice?
I see that at least one parts supplier has .080" pistons for 750cc flatheads ( http://www.45restoration.com/ ) so hope is to bore for a set of those to clean it up and get back to an appropriate bore clearance. 45restoration in their catalog recommends .003 - .004" rather than the .001 - .0015" that the manual I have recommends for the early Sportster. Thoughts?
Also, this bike has 18mm spark plugs which from what I can find on the internet is not correct for a KHK. It has Champion K-12G fine wire plugs installed, but thinking of replacing with NGK A6 or Champion D16 which it appears are appropriate for earlier flatheads. Again - thoughts?
George
Vancouver BC