Sunday, July 27, 2008

No fault found

Well, not in the gearbox anyway. After carefully disassembling the gearbox, labelling all the bits and pieces to ensure a proper reassembly, I couldn’t find anything wrong with the box. Gears all slid smoothly up and down the shafts; no broken teeth or unusual wear patterns; no excessively worn bearings. In short, everything seemed just fine.

However I did find a bottom end full of powdered aluminum. The last person who had the engine apart had reassembled it with the forward cam chain slipper installed incorrectly. As a result the cam chain wore away a large part of the inside of the case, generating a huge amount of aluminum powder that was being carried around by the oil. So my thinking is that perhaps (hopefully!) this was all just a bit of aluminum grit that caused one of the gears to bind on the shaft, and now that it’s cleaned out no more problems.

That’s my theory and I’m sticking to it.

So now it’s time to reassemble the motor and put the whole plot back together. Fortunately the gaskets all came off the cases without undue damage, so they are being re-used. I expect it may leak a bit, but there’s really no option as gasket kits for 34 year old motorcycles are not that easy to come by. And I have a coffee tin of metric bolts somewhere (just need to find it – not necessarily an easy task) that I can use to replace all the stripped Phillips-head bolts originally used to hold the cases together. Even with an impact driver, they are getting tough to remove and replace, so I’ll do what the factory should have done in the first place and use ‘advanced technology’ fasteners.

Aside from the aggravation of having to tear it all down and put it back together, this little exercise did give me a chance to check out the engine’s innards, and they are in very good shape indeed. The barrel is clean with no scratches or serious wear marks; the piston and rings are fine; there is very little carbon build-up on the head and valves; bearing play is minimal; and generally everything looks good. So, aside from the cam chain slipper problem, it looks like the engine has been well taken care of and not abused. That can’t be said of the rest of the bike as it shows a healthy dose of ‘good honest wear and tear’, but I’m now at least confident that the engine isn’t the weak link.

And, truth be known, taking stuff apart and getting it all back together in working order (without any shop manual I might add) is kind of fun!

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