81' parts compatibility

[gbftats7]

Hello, I purchased an 81' xs650 motor. Its missing the camshaft and all the guts from the valve springs up. It seems more cost effective to just buy the top end with the cam and components rather than fishing on ebay piece by piece. Im curious if 74-82 will be compatible? I saw an 81 top end, but the 4 bolt cover has a different pattern than mine. Any help would be appreciated

 

[gbftats7]

 

[Jim]

Im curious if 74-82 will be compatible?

Yes. No changes in those years that affect interchangeability. One thing to watch for is the numbers on the head and rocker box need to match. The cam journals are line bored as a set.

 

[gbftats7]

Yes. No changes in those years that affect interchangeability. One thing to watch for is the numbers on the head and rocker box need to match. The cam journals are line bored as a set.

thanks for the info, i'll take a look at mine in the morning.

 

[5twins]

The one in your picture, is that yours? The top cover is on backwards, lol. That's why the pattern on the 4 stud valve cover is off. Also, that head is older than an '81. The "tell" is the little nubs or protrusions on the ends of the rocker arms. They were there for the compression release to act upon on the '72 model, but were carried on into '73 and maybe even '74 even though the compression release was removed. I guess Yamaha had a lot of them to use up, lol.

 

[nj1639]

The one in your picture, is that yours? The top cover is on backwards, lol. That's why the pattern on the 4 stud valve cover is off. Also, that head is older than an '81. The "tell" is the little nubs or protrusions on the ends of the rocker arms. They were there for the compression release to act upon on the '72 model, but were carried on into '73 and maybe even '74 even though the compression release was removed. I guess Yamaha had a lot of them to use up, lol.

Yeah, if that's the sellers photo I'd be a little wary.......

 

[gbftats7]

The one in your picture, is that yours? The top cover is on backwards, lol. That's why the pattern on the 4 stud valve cover is off. Also, that head is older than an '81. The "tell" is the little nubs or protrusions on the ends of the rocker arms. They were there for the compression release to act upon on the '72 model, but were carried on into '73 and maybe even '74 even though the compression release was removed. I guess Yamaha had a lot of them to use up,

ah thats better! i just slapped everything together when i picked it up so nothing would get damaged, the alignment pins were in the wrong locations.

 

[gbftats7]

Yeah, if that's the sellers photo I'd be a little wary.......

it was an 18yr kid rebuilding it, i'm going to check everything.

 

[nj1639]

Mystery solved! Too funny......it does show there are some discerning eyes around here........

 

[5twins]

As mentioned, the head and it's top cover are a matched set. There are numbers stamped on the front of both so check yours and make sure they match .....