Ariel Owners Motorcycle Club

Here's a picture of my WNG, resting by the side of the road, after a chain snapping and jamming incident last night.
The engine, lower, sprocket, came off it's taper as the chain jammed itself against the case.
Looks to be no damage ... the taper looks good enough.
I have a new sprocket and chain somewhere, which I'll chuck back on tonight

it wasn't silly cold, it wasn't raining, I wasn't carrying the 10 year old pillion although it was dark and annoying (as I was on the way to the pub)

Not good

HI Admin you looks like you was lucky not to break the oil pump as well

Not good, but you were lucky. A school friend of mine had a similar incident when the magdyno bolts fell out and the magdyno moving jammed the chain. The camshaft sprocket moved on the cam, effectively welding the two together. But when I bought the bike a few months later it had been fitted with a brand new magdyno.

John,
Any idea why it broke? I wouldn't have thought the chain would be under any significant stress, certainly not enough to snap a link or roller?

Cheers
Alan

You're very lucky not to have cracked casings so think of it as your lucky day.

I'm sure I've seen a thread somewhere about timing chains breaking and the mystery of it all. The upshot of the thread seemed to be that it can happen and that you should buy the best quality chain that you can.

The obvious 'others' would include...

Make sure the sprockets are aligned
Do not over-tighten the chain

This WNG is my winter one. It's not been started since march ?
It went third time, I checked all the other two chains, refilled the primary, checked the charging and the oil return and let it idle before the of about 8/10 miles before the stop.

Riding wise. I was slowing down for some traffic lights and a right turn. An odd sort of noise and then loss of engine. Clutch in and coast. A siezure was my first thought and I rolled the bike back and forth and gear, once it was off dual carriageway, to ascertain that it wasn't.
The only odd thing was that a couple, in a car, passed me literally just before and I think were indicating that something wasn't right or had fallen off or something (they may have been waving.. not sure ). This was why my first thought was a wet sump, failed return, clouds of smoke and the the feed had run dry. not so.

Nothing else in the case apart from a stray roller and a bit of the chain. The chain itself is mangled on one link, but that could well have occured post failure. it was endless. Nothing missing off either sprocket.

The replacement went on with just over 1/4" up/down, so it's possible this broken one had worn a bit and was a bit slack but there weren't any grindy marks off the inside of the case.

Everything seems to spin as it should inside ... A mystery I guess, although it's entirely possible the chain was older than I am.

one side has sheered or broken off .
It's a renold chain/made in england

it is unusual for a good make chain to break but it can be a fault in the metal or made on a Friday i have seen it a few times over the years the roller just breaks up or the link go even with a good chain it can be lack of oil geting on the chain

Work on the assumption that it was the original chain, made in wartime conditions with an expected life of a few weeks for the bike. So failure at 70-odd years isn't too bad and at least it didn't wreck the engine, not to mention the major benefit of you not being under enemy fire when it went!