What is this? XS1f with four bolt tappet cover?

[ProSimex]

So took the top end off my XS1 engine today so I could check everything out. As a bonus this would also lighten it up for the trip to the basement(and out of my dining room). Everything seems tickety boo. I figured I would get it honed out and put new rings in her. This presented a problem as XS650central doesnt carry stock rings for an XS1. I asked Hugh where to source these and he suggested calling Gary Hoos. I had a look at his site and oh my.

700 big bore with 10.5-1 comp!


Fuck me sideways Margaret thats TASTY!

Looks like the engine is gonna get all kinds of love this winter. I dunno where Im gonna find the money to finish the frame now.....

Some pics

Getting ready

Oil line and ignition off

Gunnar wants to help. I only noticed that the wife took this pic once I was taking photos off the camera.

Valve cover off, loosened the cam chain and pulled the cam bearings out, allowing me to slide the cam out without cutting the chain. Im gonna put a new chain on before buttoning this back up, but for now it can just relax in the bottom of the case.

And the head is off. All parts are in ziplock bags and carefully put away.

I think Im gonna have to just take my time and do this engine right, even if it means not having it ready for next season. I still have my TX to ride so I'll be ok. Rephase, 700cc, pamco, PMA, ect. By the time I'm done Im sure I'll have spent enough money for a new triumph!

 

[Patches]

That's not an xs1 motor in your pic. Unless someone has swapped out a later model head on it.

 

[ProSimex]

Engine numbers are s650-015863, which make it a XS-1F made between 71 and 72. Does the "F" make it not an XS1 anymore?

 

[5twins]

The left front 4 bolt valve cover makes it not an XS1, or at least the head anyway.

 

[ProSimex]

Well what an earth have i got here then? It has been apart before as faras i can tell, so maby there is something interesting goin on?

 

[Patches]

Need more pics to tell for sure, like of the chain tunnel of the cylinders, and the bottom of the case. The XS1 case didn't have provisions for a starter, and the chain tunnel had a brace between the cylinders. But your head is clearly not a XS1 head.

 

[XSLeo]

On the VIN to year chart I have your number is a XS1F.
The XS2 was the first year of the electric start. In 72 and 73, the XS2 and TX650, they had a weak starter and battery. They put the decompressor valve on to help it start with the electric starter. In 74 they used a stronger starter and a bigger battery. This did away with the decompressor.
Your head has the four bolt cover of the 72 and later engines. If sounds like at some point the engine was apart and the head replaced with a 72 or later head. No biggie. It will run just fine.
Leo

 

[ProSimex]

Yay franken bike!

 

[xstra]

counting the teeth on the cam will tell you what crankshaft and camchain you have