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I am working on the engine. Does any one have the specs for engine clearances: piston to cylinder wall clearance, ring gap, valve to valve guide clearance Any help will be greatly appreciated.
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Nothing specific on that engine, and I assume you are talking about the flat twin, but I might offer some guidelines.
For piston clearance, .001" for every inch of bore is pretty standard. It would not hurt to add an additional thou for air cooled engine, esp. for rear cylinder. Ring gap, .003" for every inch of bore. An extra thou does not hurt on an air-cooled engine. Valve guide clearance of .003 + .0005 would be safe.
Again, these are NOT specific to the flat twin. But are general guidelines for engines of that period. I can check with a friend who may have specs. if noone else jumps in.
Cheers,
Sirhr -
Hi Burch,
Maybe I can help.
I have rebuild my engine last year and can send you some photo's if you like.
You can find all the information in the service dept. Bulletin volume 1.
This is a book with service bulletins of harley davidson.
In the bulletin no 90 of feb 1921 there is alist of piston and rings including the WF and WJ models.
I can make a copy if you like.
For my own bike I had to go to oversize +060 due of a problem with the pistonpin.
I have bored and hone the cilinder also tappered like they use to be original althou there are different upinions.
I did not found the correct pistons but the harley WLA 45 has the same bore so I used new alu pistons who have oval skirts so less contact with the cilinderwall.
I had to solve the problem of a large pistonpin hole but therefore I bought pins of a vespa 150 cc.
The only difference is the weight of the pistons.
I have used the bike for 1000 Km and its working perfectly
If you want to know more please contact me.
PeterComment
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Thanks for the information. I would like a copy of the bulletin. You can email it to me olburch70@gmail.com or regular mail 5625 Woerner Rd, Manitou Beach, MI 49253. Doc BurchComment
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