Broken primary chain

cbranni · Post by **cbranni** » Sat Apr 30, 2011 9:10 am

Wheeled the bike out yesterday to go for a spin, started as usual first kick, as it started there was a bang!!! primary chain snapped, as luck would have it no damage done and a clean break, now the question is can I slip a connecting link in as a fix till new chain from JSL arrives and as stocks are low, I may have to look elsewhere so may take few weeks, and as I use the bike to commute 15 miles to work (when its dry) am I pushing my luck, any thoughts guys.........thanks
Colin

TommoT · Post by **TommoT** » Sat Apr 30, 2011 10:59 am

It's a bit of a gamble, the breakage could be an indication that the chain is worn. But maybe you know the approximate age/mileage of the chain? If it has endured a fair mileage, it may be risky!

BigAl350 · Post by **BigAl350** » Sat Apr 30, 2011 12:18 pm

A new chain is easily available from several sources. I replaced my totally-knackered endless duplex on my G5 with a duplex chain and split duplex link for under £20 (Regina brand). A bit of a fiddle to get on but it's been fine for many hundreds of miles now.

The 250 Lightweights (generally) used a a simplex chain with split link quite successfully and there's not a huge amount more power available from the 350 so a split link should be fine on the 350 - assuming the original chain is not excessively-worn. Finding out just why your chain broke in the first place should be investigated as a matter of urgency though.

Al

Rob Harknett · Post by **Rob Harknett** » Sun May 01, 2011 10:26 pm

What model is the bike with the broken chain.
You may not discover why it broke. Assuming the reason was not because it was so worn out and slack and you have the correct gearbox adjuster which locks it at the correct tension. If its the tin chain case, make sure one of the little screws that hold the chain case on the crank case has not worked loose.
You may not spot this screw when the oil drains out. It happened to a friend once and I said the screws are missing, they must had broken the chain when they came out, he said what screws. ( and tab washers )

clive · Post by **clive** » Sun May 01, 2011 10:46 pm

G5 Rob, in the title your comment very appropriate for heavyweight

cbranni · Post by **cbranni** » Mon May 02, 2011 8:09 am

Thanks for the replies guys, when I stripped it down the clutch basket nut was loose, with about an eigth endfloat, (sure I tightened it up)this I imagine was the cause of the breakage.
Anyway I had a link from a local transmission stockist who kindly opened his shop on Saturday for me, I tightened said nut with pneumatic impact driver, boxed it all up and running fine, done 70 miles since, good biking weather.
While I'm here .......when I'm tootling along at 40 I have an annoying noise almost like a vibrating noise from engine, power on it goes, power off it goes, been there since rebuild, its not got worse after 500 miles, engine is solid, no smoke, no rattles, small end was changed, big end was good, the piston still on standard size, have a third gear whine, I can live with that, was thinking breather rotor from what I have read, any thoughts guys?
I have to say I am well pleased with the way the bike has turned out, I get so much pleasure from it even the commute to work is enjoyable including the 28 sets of traffic lights each way.
Cheers
Colin
PS .........looking for another bike to restore now, it has to be Matchy/Ajay for 2 simple reasons, the excellent JSL service and this website.

rex.webb · Post by **rex.webb** » Mon May 02, 2011 10:03 am

NOW !!!!!!!!!!!!!!!!!!!!!!!!!!!
YOUR CHAIN !!!!!!!!!!!!!!!!!!!!!!!!!!
IF THE SIDE PLATES of the CHAIN ARE WORN ...... THIN ????????????
AS THEY MAY WELL HAVE BEEN !.
Your courting trouble using that chain.
REDE with CARE and LIVE LONG to ENJOY your BIKES !

cbranni · Post by **cbranni** » Tue May 10, 2011 10:39 pm

Just an update, new Regina chain arrived from JSL and fitted last weekend, a good price too, no more courting trouble now Rex..........thanks
Colin