Mint 400 Cylinders

[tlanders]

I have two Mint 400 cylinders, one has a "1" stamped on it and the other a "2". I assumed the one with the "1" was the first type of Mint 400 cylinder and the one with the "2" was the later variety. However, the 2 came off a 1974 engine and the 1 came off a 1977 engine. What gives? Also the 2 engine's inlet ports overlap the transfer ports more than the 1 does and in general looks like it breathes better?? The top of the 1 cylinder has a narrow ridge (.075" wide and .020" high) sticking up and 2 is completely flat. Have these cylinders both been put on the wrong engines ( what are the chances of that?) or do the 1 and 2 mean nothing? Any help would be appreciated. Teddy

 

[Paul Danik]

Ted,
   As none of the "KTM experts" has answered your question, I will venture a guess or two.  I believe that BSA used to match the cylinders and pistons as close as possible when they were new.  An undersized cylinder was matched with a slightly undersized piston and vise versa.  They were stamped with a + or - as needed, maybe KTM used the 1 and 2 for the same purpose.  My other thought is that in the past 25 years who knows what all engines and cylinder swaps could have been made. Just my 2 cents worth!!
Paul

 

[tlanders]

Paul, thanks for the ideas. I keep hoping that someone knows what the transfer ports should look like and can help me ID these cylinders. Teddy

 

[Mike Lenz]

Ted  I have looked into this issue. The part number for the cylinders on 400's only changed once , in 1977. From what I have been able to tell the 77 cylinders on have a third center port in the middle of the V transfer port. However Ive noticed that the amount sticking up where the head bolts on is different in hight from the top cyl fin on some pre 77 cylinders?? Other than that I have seen no differences. I would guess one of your cyls has been attacked by a porting tool!