Crack in crankcase.

[TwoJugs]

I would try the JB for a while with an eye on it before and after every run to see where it goes. A small groove ground in the crack to allow some of the JB Weld to get in shouldn't hurt. If it gets worse you will probably need to tear down and split the cases to do it right antway. That usually means grinding out the crack and JB again and possibly stop drilling the crack too before welding. Die penetrant will help to find the real ends of the crack.

 

[RatyXS]

That is always something that could possibly happen. However tig welding it will be much more precise/channeled heat then stick or mig welding. I have never seen the thickness of the case on one of these but based on having had dirt bike and atv cases fixed in the past, it should be able to be done. Should the case be split to do it, yes prob. but can it be fixed the way it is yes probably. Just have to keep a rag with water to cool the area in between weld passes, naturally a fire extinguisher just in case. LOL

 

[rebel542]

The bearing in your pic is for the shift cam. If it's not leaking now you can try some epoxy and it may work for a while. If you tear it down to weld it go ahead and buy some used cases and replace them. Must be a matched set.
Oh, by the way. Replace the chain and sprockets and keep them adjusted!

 

[Dancingratt]

Does anyone know if a 78xs f crankcase will fit all my 79xs sf bits.
I have found one but not sure if it will all fit straight over. ?

 

[gggGary]

yup 74 to 83 should all swap, 78 to 79 FOR SURE no issues.

 

[Dancingratt]

Thanks mate

 

[acebars]

Sorry to be off topic, I've never had a chain snap, can I ask why you think it happened? Did you need to replace it or was it set incorrectly?

 

[peanut]

a potential problem is the selector drum bearing . The needle race cage is extremely thin and would buckle under the slightest pressure if not supported by the surrounding case.

Dynamic forces on the bearing hole area could cause the needle race to break up as the crack goes right through the side of the bearing surround.

I would look to see if there were some adjacent fixings I could use to support the cracked area by bridging across with a steel bracket fixed to the crankcase bolts perhaps to stop things moving around and weakening the case further.

Regarding welding ...a bike shop welder is the last place I would take that job . I would take it to a specialist Tig welding engineer who is trained and qualified in working with aluminium but to be frank, a matched pair of used cases is the most economical solution here

 

[650Skull]

A crack like that is only going to get worse with the vibration the XS650 has if you keep riding it.

I don't know where you are in Australia, but if you join the XS650 Club here, (Aus), then there would be someone in your area that would be able to help you out with local knowledge workshop/welding and maybe hands on help.

There are members from Darwin to Perth to Adelaide.

 

[gggGary]

If misery loves company this should cheer you up...



I had stripped these cases bare, knew the bolt hole was busted but didn't see the other damage till this evening.
You can see the marks where the chain hit. Not a problem for me, it was just a parts hulk engine.