Disassembly of bottom half of a 750

[Anonymous]

Ok GS Pros, I am in need of some advice. I am currently in the middle of a complete rebuild of my '78 750E. I have everything removed. (i.e.: Cams, Head, & Jugs). I am planning on pulling the bottom half of the motor out of the frame this weekend to touch upsome rust spots on the frame,work over my wiring and some general cleaing. My question is this: Is it worth cracking open the bottom half to check out the bearings on the crank. I do not have any leaks and I haven't noticed any signs of the crank bearings starting to go. What kind of work is involved in opening up the bottom half of the motor. If I do go ahead and open it up, what kind of things should I keep in mind for re-assembling it. I am concerned about removing the timing mechanism. How should I go about changing the bearings?

Thoughts...advice...& or opinions are welcomed.

Thanks in advance.

[Anonymous]

If you are doing a complete rebuild I would crack the cases just to replace the cam chain. I have heard of people replacing the cam chain by breaking it and using a master link. (I'm not to crazy about the idea.)

Good luck with the rebuild.

Roman

[Anonymous]

I'm with Roman - replace the cam chain. I would also replace the crank seals, output shaft seal, and the plugs on the transmission. Clean and inspect everything. When you assemble, use Suzukibond, Honabond, Yamabond, or similar - a thin film is all it takes. If you put too much on it squeezes out, not enough and it doesn't seal. There is also an o-ring that fits the oil passage between the case halfs that I would replace, There may be a couple more, but you can find them on an exploded diagram.

Yes, it's worth it - at least to me. I hate doing something half-assed. Those seals are old, they could begin leaking any time, even if they don't now.

[SqDancerLynn1]

I agree 75% of the work is already done, you already? bought the gasket kit? SO do it

[Anonymous]

I am planning on doing the machining work this weekend. My father owns a machine shop so that will help keep the cost down. Will the bearings come out realatively easy? I have been told that they are "shrink fit" installed.

[KW]

If you're gonna strip the bottom part of the engine, remove the clutch basket, etc. BEFORE you take the engine out of the frame. The nut was an absolute b'stard to get off on my spare (out of the frame) engine as I couldn't easily stop the shaft on the other side turning!! #-o

[SqDancerLynn1]

For a 78 2 valve motor the crankshaft is a roller bearing and it should be OK. The only thing to do is make sure the brgs turn freely, no rough spots. If they need replacement it gets very expensive and I would send it out to someone the has the proper fixtures to repair it