812 pistons

[i:1pfwzgb3]I found that .006 worked best in my 1940 Indian 4 cylinder motorcycle (2-3/4 bore) but I know here we are talking air cooled. Ross recommended .006 probably because of Cord's history of overheating. Tom[/i:1pfwzgb3]

I thought forged required less clearance than cast. But I could be wrong. .006 sounds like a lot of clearance. I use .001 for each inch of bore, but would certainly go by manufacurers recommendations.
CORDially Mike

They made the pistons with .006 clearance. The skirts are approx 11/16" shorter than stock. I believe forged pistons require more clearance than cast ones. Rattle or not I can hardly wait to hear this thing run. I guess I was not sucessful in posting pictures. Tom

My experience with jahns pistons is the skirt is to short ( compared to the original )with to much wall clearance. so they rattle until they warm up. as where as we do not run these engines at high temperatures????
my 2 cents
K Clark

Hi Thomas, I am curious as what piston to sidewall clearance they recommended for the pistons?
CORDially Mike

In the past I have had good luck with custom pistons from Ross Racing Pistons form California in my antique motorcycles. I sent them a sample from my 812 Cord. They made me a set of modern forged pistons to fit the bore size I gave them. They are a 3 ring piston with a .875 dia. pin. The cost was around $1000.00 including rings,pins and spiral locks. In case anyone is interested my job # with them is 120829VF. This way you do not have to send them a sample. I will see if I can suceed in posting a picture of the pistons.