Bugga, bugga, bugga (broken dynamo chain)

[Worty]

Look guys, I know there may be topics on this already, but I need a bit of convo as I'm a bit p****d off.  Returned from my usual jaunt to find no charge on the ammeter.  Checked the wires, which were the culprit last time, then into gear to double check the drive - no *&^%^& movement    Whipped off timing cover and, sure enough, broken dynamo chain link.

So, I've rescued the chain and broken link, presumably nothing will have entered the engine as it's sealed within the timing chest.  I've noticed some deepish grooves in parts of the inner timing case where the chain had previously been neglected and chewed into it.  Chain was checked a short time ago when I had to replace the mag fibre wheel and was fine.

Question - should I go for belt drive kit or just put another chain on?  If I go for the chain, do I remove the dynamo or engine sprocket to fit?  Finally, without looking at my manual, what's the procedure for adjusting the chain?  I know it has to do with some kind of cam operation (I think).  How often should tension be checked?

Humour me on this folks, I hate being put off the road and want to fix asap - and it's going to be a nice couple of days.

[muskrat]

G'day wortluck.
I put belts on both of mine. At first I snapped a few till I got the tension (or lack of it) right. I found that the screw boss had been eaten by the chain and had sharp grooves so I cut it off and used a countersunk screw in there. I was worried the belts were rubbing on it causing their failure. On the + side the ratio of the belt system increases the dynamo speed bring the charging on lower in the rev range.
To adjust you loosen the strap and turn (spin) the dynamo to get the desired tension. Set it a bit loose as when you tighten the strap it will turn the dynamo a little tightening the chain/belt. So you have to guesstamate the amount.
Cheers

[Worty]

Cheers musky.  I like the sound of belts if only because they cause no damage if they break.  Chains in an ally case are always a cause for concern.  I guess it's a toss up between a 100 GBP kit and an 11.00 GBP chain.  Either way, I need to get back on the road asap (also have a broken front mudguard stay - vibration fracture).

This is just after I got her running well after a misfire.  That time it was the HT lead on the L/H pot that just pulled straight out of the pickup - only had one small wire remaining.  Brushes were a bit oily though, is that another problem.  The slipring wasn't oily?

[berger]

I have not been to the pub , private msg sent wortluck

[duTch]

 If you have the pennies for a belt drive, well worth the investment. Like Musko, I stretched the first one having it too tight (SRM/Syncroflex), but have now done 6 or 7 Kmiles since intstalling the new one. Seems the kits recently discussed have the nod of choice (wider belt and Mike is a member here).
 I run my belt quite loose now and it doesn't seem to bother it, adjusted so the loose side, (opposite the drive side) is clear of the boss that Musky mentioned, though they'll both be tight/loose at some stage, keeping in mind that it rotates in a anti-clock direction.
 **Not fit and forget, still need to check periodically, like when doing oil changes and want to drain the oil in the pump cavity....

[berger]

unless your riding a long way at night bang the case on and enjoy, I use meths on a cotton bud {carefully} to clean inside maggy with plugs out and in 4th gear turning back wheel. what type of chain do you want? continuous or one with a split link.?{let me know before Monday dinner time please} if continuous you undo dyno clamp and spin it towards engine when you've fed it over drive sprocket, I carnt remember now if you have to drop drive sprocket  off its taper, someone will know..then adjust to a 1/4 inch play on the top run. as musky says you may well find dyno will tend to tighten the chain as you tighten the clamp, you might have to play about a bit to get it correct. I fitted one of the v belt drives a few years ago and for 60 quid its working well considering the heat the v belt gets,,,, *idea*thinking again I recon drive pully has to be dropped off to fit continuous chain. and finally don't panic mr mainwareing they don't like it up em!!

[duTch]

 I was going to say a chain would be a quick easy fix, but forgot....

 and I was thinking this too...if it's endless..

 

.....*idea*thinking again I recon drive pully has to be dropped off to fit continuous chain. and finally don't panic mr mainwareing they don't like it up em!!  

[Black Sheep]

A properly adjusted and lubricated chain will last indefinitely. I would stick with a chain. The large sprocket is fixed by shear rivets to protect the cases in event of a broken chain jamming the sprocket. BSA did think it through. 

[bsa-bill]

both my bikes - belt drive
First one was SRM - still fine no problems, the second was very similar but not SRM it's still going fine as well,
First thing I do on any future project .

[Worty]

Thanks guys, with a special thanks to berger.  I've no idea how old the chain was or what quality it was.  With hindsight, I would have asked for the chain to be replaced when the engine was rebuilt, but it was deemed to be serviceable.  It was adjusted correctly when I checked it about 1k ago.  Interestingly, it seems no damage was done by the event with the chain coiled up just above the drive and not in contact with it!  Nothing appears mangled apart from some grooves in a couple of places which were a result of neglect over the past 50 years or so.  Thankfully, the shear rivets weren't needed.
Someone said getting an endless on is possible without removing sprockets.  The trick is to manoeuvre the dynamo and persuade the chain on.  What do you think?
Berger's right, of course, I could just bang the cover back on and ride - if I had a serviceable gasket of course.  Actually, I could manage without a gasket as I discovered it only has a mild leak metal to metal - hmmm.

[JulianS]

Belt drive is quieter and the drive pinions easy to remove and slightly gears up the dynamo speed. Would not want to go back to a chain driven dynamo.

Mine is from DVR;

http://dynamoregulators.com/drive-belt-kit.php

[RogerSB]

This is SRM version. Already on there when I bought my current GF but if I ever needed to replace it my choice would be the version from Dynamo Regulators.

[Worty]

Cheers guys.  Slapped cover on (without gasket) and went for a 120m run - just a couple of spots of oil!!!  Leaks less oil without the gasket.   Found some bits of one the rollers but not the tiny bits for the broken link.  Cleaned out all the grease and checked oil, but no sign   Bike was noticeably quieter (ran beautifully) without the chain and I was intending on a 200m run.  Unfortunately I had to return with a couple of cable ties (courtesy of a random tradesman in a small North Yorks village) holding the front mudguard on because one of the side brackets broke in half (this was in addition to the lower stay breaking yesterday). 

There are words to describe the quality of materials BSA used but I cannot, in good conscience, use them here.  I guess they may be half a century old.  By the way, my side stand also crumbled, that's why I only use a the centre stand.

Think I'll do a diary of all the breakages/breakdowns and post them.

[RichardL]

Think I'll do a diary of all the breakages/breakdowns and post them.

Sorry, but all post limited to under one terabyte.

Richard L.

[RogerSB]

Could change your name to Worstluck?  .

But here's hoping you don't have any more probs  .