'72(?) engine ID and valve adjustment question

[scott s]

I have an engine that came in a parts bike. The bike was a '74. The color, VIN, mufflers and other clues led to to belive that it was a '74.

The engine, however, almost certainly isn't. I've used the "How to ID your model" charts and that just led to more confusion.

The number on the engine appears to be 3650-120924. It's hard to read behind the engine mount, so I'm guessing that the "3" is and "S". S350-120924 would put this as a '72 engine.

HOWEVER, my manual says that the early engines hold either 3.2 or 2.6 litres. The engine case is clearly marked "oil capacity 2500cc". which would put it as a bit later.

If it IS an XS 2 or TX 650 engine, the manual states MUCH wider valve clearances. .006 and .012 vs. .002 and .004.

What do I have and where would you adjust the valves?

 

[gggGary]

.006" and .003" is "correct" for all years. There were no significant changes to the head through the whole production run. I think the general consensus was they fiddled with the clearances mainly to stop the horrible valve clatter the big gap creates. I tend to use .006 and .0025 I might go down to .005 on the exhaust some time just to see how it sounds.

 

[Scrambled]

I think the oil capacity is for when you overhaul it takes 3.2 l and an oil change is 2.5 . On my '78 the book says 2.5 fill for a dry motor and 2 l for an oil change, or something like that.

 

[scott s]

Well, this engine was completely dry. We had pulled the sump plate, etc. I put in 2.5 qts. and it brought it to the correct mark on the dipstick.

I'm pretty sure we used .004 and .006 on the valves. It sounds fine. No unusual noises or ticking.

 

[littlebill31]

Scott,
I believe you are referring to the stamp on the case regarding oil capacity. I'm pretty sure, off the top of my head, that '70-'71 had "3000ml" where as the '72-up read "2500ml".
And I think the '72 still had the compression release.

 

[scott s]

This engine didn't have the compression relief valve cover, but the rockers are different. They have that extra "arm" or "ledge" on them.