Cam chain tensioner ??

[racerdave]

First, oem neck decal state's 7/78 mfg date. Title says 1979. Looking at the tensioner pic's on Mikes XS, I have type E, with the cap and locknut, for a 1980 -1984. Are they interchangeable? Maybe the jug was changed?

Frame and motor case both start with 2F0

I have some original paper work that shows this was first sold in June of 1979. It states model XS650SF-B

 

[5twins]

Yes, they interchange. I stuck an '80-'84 style in my '78 to gain the locknut feature. The housings appeared the same from what I could deduce so I just swapped in the newer screw, spring, plunger, and locknut. Acorn nuts were the same so I continued using my original because it was in better shape.

It's hard to pinpoint exactly when Yamaha made the change. Most '79s I see seem to have the locknut. Some '78 Specials seem to have it too. Mine is a Standard and did not have it. I guess it really isn't that important to know exactly when the change occurred. What is nice to know is that the later parts will simply swap into the '78 housing ('77 too I would imagine) so there's no need to change housings as well.

I'll be going to look over a '78 Special this week sometime. I'll be sure to check this item out.

 

[racerdave]

Thanks 5twins. Just want to be sure.