Getting over 7 miles out of my G12CSR

Information relating to the Matchless G12 or AJS Model 31 650cc twin
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Pat Watty.
Posts: 1
Joined: Wed Oct 12, 2005 10:45 pm
Location: UK

Getting over 7 miles out of my G12CSR

Post by Pat Watty. »

Just rebuilt my CSR and fitted auto advance sprocket on freshly reconditioned magneto. With a new pair of 1st oversize pistons in rebored barrels, everything seemed to be going swimmingly.

Started first kick after 9 years off the road! But I suppose they all say that. In fact its true.

One small problem. Goes like a train for almost exactly 7 miles and then the left hand pot starts to cut out. Runs on right for a while but when stalled is completely impossible to restart. Left hand pipe is just yellowed - right seems to be slightly cooler or maybe just freer flowing.

Checked and rechecked the timing. Checked and rechecked valve clearances. Checked and rechecked carb settings. Oil flow is fine

Any idea about my Gremlin?
Rohan B.
Posts: 136
Joined: Wed Oct 12, 2005 10:45 pm
Location: AUSTRALIA

Getting over 7 miles out of my G12CSR

Post by Rohan B. »

Pat,
No magic solutions come to mind.

What grade of what plug are you using ? Have you tried fitting a NEW set of plugs when this happens ? What colour do they show ? What fuel are you using, there has been some funny problems with lead-replacement fuel over your way..

You checked that the breather hole in the fuel cap is clear, and fuel can flow to the carbs when this happens ?

If you had a spare magneto, I'd suggest that you try it, since this problem still sounds like magneto. Did the reconditioner fit a new condensor in it ? Is the new condensor a good one, or an ancient nos one ?

Have you tried running each cylinder one at a time, since it sounds a little like the left one is working harder ? Can you check the spark timing with a strobe, to be sure both are firing on the same ignition timing.

How is the mageto rigged to switch it off, and is the switch reliable ?

Just a few ideas other folk have reported as the source of their problems..

hopethishelps, and good luck.
Rohan.
burrage
Deceased
Posts: 88
Joined: Mon Jan 01, 1996 12:00 am
Location: WARWICKSHIRE UK

Getting over 7 miles out of my G12CSR

Post by burrage »

You may have a blocked air hole in you petrol tank cap!
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