Poor Running

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
steadyrider
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Posts: 23
Joined: Wed Aug 25, 2021 1:41 pm
Location: Northumberland

Re: Poor Running

Post by steadyrider »

Thanks all,

An update on the above which I'm still to rectify.

I've steeped the tank in white wine vinegar - its' spotless but just in case I've fitted two new brass taps (with filters), two inline filters and stripped and cleaned out the carb again.

New coil, new condenser, new bob weight springs. Timing set as per the manual with bob weights open (fully advanced).

The bike still starts first kick and revs fine on the drive but struggles under load instantly.

The push rods are adjusted so that when both valves are closed they turn freely but with no slack up or down.

I've taken the rocker box off today and took the springs off the exhaust side. The valve seems to fit tight with no play and moves smoothly.

I've got a couple of things left to try - using the timing disk to determine whether the valves are opening at the correct time and or stripping out th e points, auto advance mechanism and checking the timing wheels are correct.

Any thoughts would be welcome.
Mick D
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Joined: Mon Mar 24, 2014 5:44 pm
Location: Aberdeenshire

Re: Poor Running

Post by Mick D »

Hi

I'd be looking at the auto advance mechanism, sounds like it may not be advancing correctly.

Regards Mick
steadyrider
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Posts: 23
Joined: Wed Aug 25, 2021 1:41 pm
Location: Northumberland

Re: Poor Running

Post by steadyrider »

Thanks Mick
I've changed the springs on the bob weights and they seem to have free movement, I've now taken the cam (rotor arm) off the end of the spiraled shaft to make sure there isn't a bit of grit or fluff impeding it's travel.
Anything else you thing I can check whilst I've got it stripped down ?

Sean
steadyrider
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Posts: 23
Joined: Wed Aug 25, 2021 1:41 pm
Location: Northumberland

Re: Poor Running

Post by steadyrider »

Just a thought whilst I'm working out how to get the auto timing plate off (extractor tool I'm thinking)

Could the the problem boil back down to the timing cams just being 1 tooth out ? - ie if the guys in my local bike shop set the inlet cam to mark 2 instead of 3 ?

Sean
56G80S
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Location: N YORKS UK

Re: Poor Running

Post by 56G80S »

Unless you know the cams are right, this item may help:

https://www.jampot.com/article_read.asp?id=431

You may need to be logged onto Jampot.com to get to the Tech Tips.

Johnny B
steadyrider
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Posts: 23
Joined: Wed Aug 25, 2021 1:41 pm
Location: Northumberland

Re: Poor Running

Post by steadyrider »

Excellent - Thanks Johnny - I think my problem is likely to be some anomaly such as this where the timing has been put together by interpreting the manual without knowing there maybe other factors in the equation.

I've also downloaded the 'follow the dots' article to see how this compares.

Once I have the cover off I'll upload a photo.

Thanks for your time in replying.

Sean
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1608
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Location: ESSEX UK

Re: Poor Running

Post by 1608 »

Leaking HT ( tracking ) under load can cause the symptoms you describe.
steadyrider
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Posts: 23
Joined: Wed Aug 25, 2021 1:41 pm
Location: Northumberland

Re: Poor Running

Post by steadyrider »

Well I've replaced the coil, condenser, plug, cap, points and bob weights so I'll try a new HT lead for what it's worth - the spares department will be rubbing their hands.

Sean
steadyrider
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Posts: 23
Joined: Wed Aug 25, 2021 1:41 pm
Location: Northumberland

Re: Poor Running

Post by steadyrider »

Update :-

I've taken off the auto advance mechanism (with the extractor tool) to uncover the timing wheels. As per the attached photo on the inlet side the pinion mark is pointing to the lower of the two dots - this marries with the 'joining the dots' technical article.

I am however struggling to following the valve timing (or just being thick !!). At TDC both valves are shut and there is a tiny little bit of play in the push rods and in the valve lifters. Because the engine is cold I'm not sure how much of this play will be taken up ?
When I back the engine up (using the back wheel - in top gear) the inlet push rod just nips up and takes the slack out of the valve lifter at 69 degrees before TDC - how does this marry with the 36 degrees in the manual ?
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Mick D
Posts: 2886
Joined: Mon Mar 24, 2014 5:44 pm
Location: Aberdeenshire

Re: Poor Running

Post by Mick D »

Hi

The valve clearances when cold are 0, adjust the push rods to this and see what you get.

Winding back from TDC to the point where the valve clearance is taken up indicates the point of full closure, not opening.

Regards Mick
Last edited by Mick D on Sat Oct 23, 2021 5:39 pm, edited 1 time in total.
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