1970 XS1 Cylinder Removal

[patentgeek]

My 1970 XS1 came with a very stuck engine, which is now out of the frame. I removed the head and have managed to free up the pistons courtesy weeks of soaking in ATF, a blowtorch, and a small sledge.

The cylinders need to come off, but there is a web cast into the cylinders that prevents removal without breaking the chain - - - and I can't find a master link. I search the archives but couldn't find any threads on point, other than this one that doesn't really describe a solution.

http://www.xs650.com/threads/xs1-engine-dissasembly-question.27467/#post-273505

I suspect this web is an early XS1 feature that was dropped on later bikes. I'm hoping I'm missing something obvious as the chain appears to be in good condition.

 

[5twins]

If there's no master link, then how did Yamaha get the chain in there, lol. You don't think they cast the cylinders around it, do you? Turn the motor over slowly and carefully inspect every link. The riveted side of the master link is usually on the left side, or points side, of the chain. It looks very similar to all the other links and the rivet job isn't a total flattening of the link pins, usually just one line across .....

 

[patentgeek]

My definition of master link is a link that can be removed without having to grind off rivet heads. . . . .

 

[5twins]

Clip style master links aren't used on these cam chains, probably not on any cam chains. You will need to grind the riveted pin heads down to get it apart. Then use a new rivet style master link when reassembling.

 

[patentgeek]

Got it. Nothing my Dremel tool can't handle. Hopefully I can salvage the chain.

Replacement timing chains on 1970 and later BMW airhead engines use clip style master links, but that's not an overhead cam engine.

Do the later cylinders have the same webbing to prevent the timing chain from falling into the bottom of the cases?

 

[5twins]

No, no cast-in webbing on the later models, but the chain has to be threaded through the rear tensioner assembly. It's possible to put an endless chain on them but it involves so much more extra work, even the factory didn't use them. The bottom end has to be opened up so the endless chain can be slipped over the end of the crank. Then, the rear tensioner base has to be split apart by drilling it's rivets out. All in all, it's a ton of extra work for no real benefit or gain. There was never a problem with riveted cam chain failures on these.

 

[patentgeek]

Just for reference, Heiden Tuning has rivet links for the Tsubaki BF05T cam chain used from 1970-73. I'll add one to my shopping list of Heiden goodies.

https://www.heidentuning.com/xs650-...am-chain-rivet-link-70--73-models-detail.html

 

[vr3506]

beware that putting a camchain on a early engine (17-34 sprockets) is more difficult than on the later engines (with the 18-36 sprockets), sometimes you need some rings and bushings to torque the cilinderhead down a little to get the chain on the sprockets ( my experience is with a new chains)
when your engine has done a lot of miles, i should put on a complete new chain!

 

[5twins]

Yes, if the motor has anywhere near 20K miles on it, I replace the chain while in there. They will last much longer than that if properly cared for (adjusted frequently and correctly) but most never were.

 

[TwoManyXS1Bs]

Just some cylinder & tensioner FYI.

http://www.xs650.com/threads/cam-chain-tensioner-on-256-motor.38674/

http://www.xs650.com/threads/excessive-timing-chain-slack.42215/

http://www.xs650.com/threads/71-xs1b-conversion-to-cafe.45115/