TR5MX clutch/kickstart issue

[the general]

Last time I rode it all was running well until approaching a T junction after brisk acceleration I went to pull in the clutch and it was rock solid . There was no warning of this symptom, it just happened. I nursed the bike home with clutch-less changes and on trying to restart it found the kickstarter no longer engages – doesn’t seem to be connected to anything now.
Any ideas on what has happened?

[minetymenace]

KS not returning and ratchet has welded everything together under that cover....timing side cover off will reveal all!

[beat]

ratchet has welded everything together under that cover

someone seams to have experience in this

[minetymenace]

And I'm not the only one beat!!

[Grouty]

And I'm not the only one beat!!

Yep ! ..... flat out in top on the old B50 across the field when it all locks up. Longest rear wheel slide I have ever done. Managed to stop before hitting the hedge.
The gear had welded itself to the shaft and locked the lot up. I had to get the angle grinder out to remove it.

[the general]

Oh dear, it sounds like a whole load of trouble that I haven't got time to deal with right now

[minetymenace]

It may not be as bad as the doom and gloom merchants (including me) have predicted, whip the timing side cover off and take a picture of the contents or gloop....

[JerryT]

And I'm not the only one beat!!

Yep ! ..... flat out in top on the old B50 across the field when it all locks up. Longest rear wheel slide I have ever done. Managed to stop before hitting the hedge.
The gear had welded itself to the shaft and locked the lot up. I had to get the angle grinder out to remove it.

What was the cause?

[minetymenace]

Kickstart not returning to its "disengaged" position, possibly weak kick start return spring, cases not aligned, some binding bearing surface, return impeded by boot or leg etc...

If the kickstart pinion is the held still by the rack on the quadrant, as the mainshaft is always spinning when the engine is running (and clutch clutching, flux capacitor fluxing etc) the poor little bush starts to get hot as it pines for a splash of oil which alas, is an inch or two below. Friction welding is a well known technique...need I say more?

[Grouty]

It was (as Gerry said) a friction welding issue. This was when I first had my B50MX many years ago and was not familiar with the foibles of BSA engineering !
I rebuilt it with all new parts and it never gave trouble again. Having said that, I sold it about a year later to a nice man in Japan. Did it last ???? Who knows.
The CCM on the other hand has never given any trouble whatsoever (touches wood !). I have been racing that for probably 15 years plus.

[the general]

Today I tried to remove the timing side cover and guess what? Just as expected 3 of the screws that were already a bit mashed up won’t come out . Two at the top, one tight at the bottom. I tried a gentle chiselling but didn’t want to destroy the heads completely. I don’t have an impact driver so I suppose the next step is to buy one, although I’ve never had much success with them in the past.

[Grouty]

An impact driver is really your best bet. Just make sure the bit you use is the correct one for the screw you are undoing. Give it a "prime" and then mate with a BFH. Replace them with cap head bolts and all will be good.

[the general]

Finally managed to remove the three remaining screws having got an impact driver and got the cover off. Inside was a lot of swarf that has come from the clutch lever actuation area, which is why the clutch lever was frozen.
The starter pinion spins on its shaft but doesn't turn the engine. I'm not sure what's happened here.

[Ian Hingley]

Is the nut on the end of the mainshaft tight?

Ian

[the general]

Yes it is - I tried to undo it but need to know the best way to lock the engine from turning.

[skippy]

A battery impact wrench is the best investment you can buy, you don't have to lock anything to get it undone.

[the general]

I'm going to do that but I’m still waiting for my son to get his staff discount card from Wickes.
In the meantime, I suppose have to get a new outer timing casing to replace the mangled one, but there don’t seem to be many advertised and those I’ve found are out of stock. I was going to go to Kempton but that was cancelled. Alternatively, I might just reassemble it all and sell it as a non-runner which would be a shame after all the years I’ve had this bike.
How interchangeable are these casings? The parts book gives different part number for each year 72 & 73, mine’s a 73 according to the engine number.

[minetymenace]

The major difference is where the points wire exits, but clean up your old one first, despite the swarf it may be OK. I's investigate why it made the swarf in the first place, that nut doesn't look like it is on all the way, how much end float do you have on the mainshaft? Has the clutch fallen off?