Replacing a broken engine chunk.

[Gcraay]

I have a 1975 xs650 that I'm looking to use for a custom build. I found one with motor and all for $150.00. Heck I was just looking for a frame. Anyway, It has a chunk out of the main casing directly above the sprocket. It is not one that will be under stress from oil pressure or kick starter or anything so I was looking to get it repaired. The chunk is about the size of a triangle cut quarter sandwich. Probably ham, but definitely not salami. In addition I do not have the part and feel that the guy I bought it from is surely not looking for it. So, can I fix it? also I will need to fab out a screw hole, cause one went with it. I see some crank cases on E-Bay, fairly cheap, but don't know if that is the way to go. Any suggestions. I will need to hire this out.

 

[Soliddrummer]

We will need to see some pictures of this in order to help you.

 

[gggGary]

Yes lets see a pic please.

Clean the crap out of that area look VERY closely, you may see this.


If it isn't cracked like that, whew. once that shift shaft bearing is involved it gets a lot tougher. The crankcases need to be kept as a set, you cannot mix and match tops and bottoms.

Someone had a hole in the back of the crankcase and JB welded it worked fine for him, for a while at least......

 

[Gcraay]

This is a few angles of the break.

 

[xjwmx]

All that's broken off there is decorative stuff

 

[Soliddrummer]

That won't effect the performance of the engine at all. That is a cover for the chain and sprocket area, it acts kinda like a chain guard. Your chain will be slinging lube all over and the flap that is missing keeps it contained under the side cover. There will be an ugly space when the side cover is attached, but it won't effect the operation of the engine. If it were me, I would be looking for new cases.

 

[xjwmx]

I would be looking for new cases.

I would take a square of sheet metal and bolt it on top of the case cover so it hangs over where the piece is broken out. It would look normal to the untrained eye. Even better, use chrome plated sheet metal and use three stainless allen head bolts to hold it on, going with the philosophy of if you can't fix it, feature it

 

[Gcraay]

Yes I'm looking for one also thanks. I was just weighing my options.

 

[XSLeo]

If you get different cases be aware that they are made in matched sets. They cast them then bolt them together for machining. Once machined they stamp matching numbers in both the upper and lower cases. Near where the clutch is.
You might get away with mismatched cases but you might also get oil leaks, bearings binding or they just won't fit together.
Leo

 

[TwoManyXS1Bs]

The 6mm screw that went in there to hold the left side cover is one of the 3 screws nearest to the clutch actuator, which tries to push in on the clutch pushrod. Those three screws carry the majority of this load, this particular one more so. The cover, without that support, could flex a little, reducing your clutch disengagement travel. Or worse, lead to cracking of the cover.

If necessary, could machine/drill/tap a fresh hole in that location, then use a longer screw in there...

 

[reidbellamy]

you could also trim back the overhang to the outer wall of the case and then trim the cover to match giving you an exposed drive sprocket.