Poor Running

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
steadyrider
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Re: Poor Running

Post by steadyrider »

Cheers Mick

Sean
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Duncan
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Re: Poor Running

Post by Duncan »

steadyrider wrote: Sat Oct 23, 2021 5:24 pm 69 degrees before TDC - how does this marry with the 36 degrees in the manual ?
Hi Sean, you really need to run the degree disc on the end of the crank or adjust want you read off the disc as the cams operate at half engine/crank speed.
steadyrider
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Re: Poor Running

Post by steadyrider »

Thanks Duncan

I did think later after Micks message whether the timing side pinion runs at a different speed and whether the timing disc would work the same on this side- that makes sense now.
If it were roughly half speed and I'm reading 69 degrees instead of 36 then it must be close.

Although Micks comment that if I take up the slack working backwards from TDC means the valve is just closing NOT opening - that's thrown me with the diagram in manual..

I'll adjust the push rods tomorrow and then re-assemble with the new HT lead I've bought and see if the problem is cured - I've never taken the primary chain case off ( aluminium kind) so I've no idea how big a job that is.

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Duncan
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Re: Poor Running

Post by Duncan »

Hi Sean, So long as you have engaged the inlet on "3" for a 350cc bike there should not be an issue, you do not need to use a degree disc so leave the primary alone. If you really wanted to do a rough check from the timing side it may be possible to attach the disc (print one off of the internet on stiff paper) to the crankshaft with some small permanent magnets.
As well as half speed the inlet cam will also rotate in a reverse direction to the crankshaft so it all gets a bit confusing.
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Pharisee
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Re: Poor Running

Post by Pharisee »

I used a timing disc on the crankshaft, a dial gauge to determine TDC and a magneto timing light to set up the ignition on my G3LS. The magneto had a manual advance which was set to full advance, of course, but I still found it easier to slacken the camshaft sprocket rather than the magneto sprocket when setting the timing.
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SPRIDDLER
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Re: Poor Running

Post by SPRIDDLER »

Pharisee wrote: Sun Oct 24, 2021 12:22 pm I used a timing disc on the crankshaft, a dial gauge to determine TDC and a magneto timing light to set up the ignition on my G3LS.
Blimey, John! That's O.K. if you've got the kit but I've had to slum it with a bit of coat hanger and Rizlas (50 papers for 35p at ASDA) for 60 years ..........(and they fit in the G3LS toolbox). ;)
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Which taken at the flood............'
steadyrider
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Re: Poor Running

Post by steadyrider »

Nice kit John.

I've put it all back together including new plug, HT lead, coil, condensor, points, immaculate tank, spotless carb, new inline filters, new bob weight springs, checked the timing, adjusted the push rod tubes, charged the battery. Starts first kick (choke lever 1/4 from fully tight) ticks over nicely but bogs down immediately when I take it off the drive.
The spark looks weak but given all the above I'm not sure how it could be made stronger ?

Any ideas welcome.
Mick D
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Re: Poor Running

Post by Mick D »

Hi

It's the classic symptom of timing not advancing, (or possibly too far retarded). Will the bike rev to 3/4 throttle at rest or does it start to falter at high revs?

Regards Mick
steadyrider
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Re: Poor Running

Post by steadyrider »

I'll give it a go......warm it up and give it 3/4 throttle - wake the neighbours up on a Sunday afternoon..
steadyrider
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Re: Poor Running

Post by steadyrider »

Hi Mick

It revs no problem at 3/4 throttle (sustained for 10 seconds)

As soon as I put it in gear and pull off it runs poorly (like a car running on 3 cylinders) and then starts to fade, when you pull the clutch back in the revs pick back up.
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