I mentioned in passing a few weeks back that after a lot of miles, my A was getting a bit of attention, mainly in the drive side roller department . . .
Well, as folk know, nothing is ever as straightforward as it ought to be.
It started with a slipping clutch.
After 50K km or more without even looking at it, not surprising really, so it was meant to be a simple case of adjust it, get some new springs and/or some friction plates and away we'd go.
With the primary off, though, 'twas obvious there was too much float on the crank. The shock absorber nut had backed off a bit, and in fact the lobes of the cams were jammed peak-to-peak. And there was close to a millimetre of float. Aaargh!
So, this simple clutch job got instantly more difficult. Always a pain when something is running apparently perfectly, but no escape.
With the crank out, it was clear the inner race wasn't tight on the mainshaft, and the shims had been taking a hammering (although they were intact luckily, nothing nasty in the cases or the oil).
The ends were excellent at -30 and the timing side bush was remarkably good. Not trusting my measuring sticks, I made a plug and progressively shrunk it without de-chucking till it would go in - which it did, at one thou over the journal's dimensions. Seemed round as well, and parallel, but that was something for those with better measuring sticks to prove or disprove.
So I sent the crank to T&L Engineering, whom I use frequently for my AMC twins and regard very highly.
Verdict was swift - yup, 'drive side mainshaft is undersize, and the thrust face on the crank web has been worn down a bit over the years, we'll sort it with metal spray and we'll probably avoid the need for any shimming'. That was where I was at when I posted something on a thread about metal-spray a while back.
Well, all seemed well, and the crank was returned looking good, complete with rods' eyes checked for ovality (both fine), ends confirmed to be virtually unworn and timing side journal and bush as being round and parallel and with a clearance of no more than 1.5 thou. Nice. Sa
So I put it together. Seemed good. New cam followers just because, new oil pump drive and spindle just because, and a few sundry bits, like rings (I'm lucky to have original BSA marked +1mm pistons and I want them to do every mile they can) and a valve guide here and exhaust valves there, with a view to getting a whole load more miles out of the motor. Oh, and some Surflex clutch plates. Thanks to C&D Autos and to British Only Austria for the various bits, delivered fast and efficiently.
Started first kick . . . but there were 2 problems.
The first was weird - no oil return but loads of delivery as the diminishing tank showed. This proved to be very lucky. STOP engine.
Lucky because the second problem was that the cage of the new roller had picked up on the new metal on the crank's thrust face and ripped off a few bits which were sitting ominously in the gauze thing at the bottom. Really ucky, because if there had been an oil return I'd have ridden off on it and probably wrecked the whole thing.
So, out comes the crank again, to see what the shards of metal are all about - and they are as described above.
T&L were very good about it, and immediately offered to do whatever it would take - which would be to clean off the excess new material and basically start again, using a hard shim if necessary.
So back goes the crank, while I figure out that there's meant to be a transverse pin in the scavenge pipe that stops the ball being sucked up the oil pump nearly - but my pin just wasn't there. Must have disappeared a zillion miles ago, and luckily the ball had previously stayed at the sucky end and not gone all the way up to close off the return.
And in next to no time, back comes the crank . . . .
Yesterday it went back in and all the boring stuff was done - engine in, transmission etc etc - and today I kicked it. First prod again (this bike always has started just like that), and instant oil return this time as I'd wound the crank by hand for long enough on the bench to prime the crank gallery and the bearings and get enough oil into the cases for the scavenge to be seen to be working before proceeding.
So a quick 40km to see all was well, and yup, same as ever.
But what a palaver.
If there's a moral to the tale, it is probably that I am reverting to my old position on metal-spraying - which is Don't!
Bit of a pain to have to pull the motor twice etc, but it's all good practice I suppose . . . and all's(eems) well that ends well as the engine has run for an hour or more today. No lumps in the slime, no funny noises, just the same as it was before the clutch started to slip and the story began. Bit more compression, and of course the state of the guts is now known to me. For this was a bargain basement bike of unknown provenance, on which in 5 years or more I'd only ground-in the valves, made a new sleeve gear bush, fixed the electrics and bought cheapo clutch plates. Can't be bad.
Now to see whether it'll do another 50K km or more without any serious hassle . . . .