The matchless lives !

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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ChrisTheChippy
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Posts: 274
Joined: Wed Feb 07, 2018 12:02 am
Location: Essex

The matchless lives !

Post by ChrisTheChippy »

Hi all
After a significant struggle another G2 will be on the road ! This little bike really put up a struggle as I knew there couldn't be much wrong with it and it was so frustratingly close to running .
Lots of little things added up to keep it from firing and I just had to be patient and deal with one problem at a time. Aside from the work I had to do on the gearbox also replacing the rubbers in the clutch , deburing the clutch plates and renewing the oil seal at the back of the gearbox . It's probably just easier to list the sequence I worked through to find the problem.
Had a good spark but still swapped the plug for one I knew was working .
Renewed the points
Thought that there was too much spark at points when they were opened manually so renewed the condenser.
Renewed the ancient coil even though it seemed to be producing a good spark .
None of the above made any difference at all bike still would not fire not even close but I now knew I had a sound ignition circuit to start from.
Cleaned carb to within an inch of it's life and renewed float needle as the old nylon one was sticking . Still made no difference but I now knew fuel system was working properly.
Cleaned and checked all electrical connections . Still no joy !
I turned my attention to the ignition timing and reset that as it didn't seem correct . Bike still would not run .
Kicked bike shut shed door and sulked for a week .
Fresh start and went straight in and checked the valve timing . Absolutely spot on so in theory bike should run . Observations of the valves moving with a bright torch through the aparture in the head and good compression meant they were seating correctly .
Ok so that meant it could only be something I had already done or fitted so I methodically went back and checked all the items one by one when I got to the ignition timing check I noticed that the advance weights had moved just fractionally and were in a slightly different position . At last I was on to something ! The weights were slipping on the shaft . Stripped ignition plate out set piston to 1/4 BTDC and tried to reset . It didn't seem to make any difference were I moved weights the points opened too soon and there was no more adjustment in the backplate to set it correctly so using a fine round file I had to elongate the slots to get somewhere near the correct ignition point . This time I gave the tapered shaft for the weights a good clean and a sharp tap to reseat them then reasembled everything with ignition timing as close as possible to correct ( well it was 11 o'clock at night by this time ).
With trepidation jumped on and gave it a kick can't describe it but I just knew it felt right , second kick and for the first time in 30 years it burst into life ! Settled down to tickover nicely while I quickly checked the oil return which was really strong and healthy.
Feeling that sense of achievement now which is one of the rewards of fettling old bikes .
Regarding the backplate were I had to file out and elongate the slots I suspect it was not the correct one for the bike . Is the points backplate for the 350 lightweight slightly different ?
So ok still some adjustments to make to the ignition timing as it's not absolutely spot on so a little more filing to do.
Have to reasemble the bike now as I didn't want to replace any engine covers seat etc until I knew it was running .
Still searching for center stand bits and all I need now is the thin rod that the spring hook's into . I have my stand stop's thanks to another club member. So if anyone has such a part please PM me .
Once it's back together I will try and post some pictures although my skills in this area are rubbish .
Cheers Chris
ChrisTheChippy
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Posts: 274
Joined: Wed Feb 07, 2018 12:02 am
Location: Essex

Re: The matchless lives !

Post by ChrisTheChippy »

Forgot to say fully advanced weights before setting ignition timing . :headbang:
Cheers Chris
MalcW
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Joined: Tue Oct 24, 2017 12:05 pm
Location: DEVON UK

Re: The matchless lives !

Post by MalcW »

Congratulations! It's a great feeling when they finally reward all of your blood, sweat, tears and curses. After spending an age on mine, and either working on or replacing a number number of parts, and fruitlessly kicking away, I was genuinely shocked when it suddenly fired up and ran.

Cheers,

Malc
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clanger9
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Joined: Sat Jun 20, 2015 9:38 am
Location: Chester, UK

Re: The matchless lives !

Post by clanger9 »

Brilliant effort - well done! :beer:

On setting the timing: you shouldn't need to elongate the slots. If you can't get it timed right, it just means the points cam isn't on the conical shaft in the right place. It's a bit trial and error, as there's no keyway - just a vague illustration in the manual. Just take the weights & cam off and move it round a few degrees...
1989 Moto Morini Dart 350
1993 Ducati 750SS
ChrisTheChippy
Member
Posts: 274
Joined: Wed Feb 07, 2018 12:02 am
Location: Essex

Re: The matchless lives !

Post by ChrisTheChippy »

Hi clanger 9
I did remove both the cam and weights and but no matter where I positioned them I still couldn't get enough room to get the firing point right . The cam fits into the weights via a small slot so in a sense it is locked into the weights . Still wondering if the backplate is the right one ? Still looking forward now I am going to try and reclaim the original number back . The bike came with no plate but I have already got evidence from the kithead trust of the original number . I will also be contacting club dating dept ( hi Roy ) to ask advice .
I was hoping to get to the jampot with this bike but won't be legal in time so have to take something else .
Cheers Chris
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clanger9
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Location: Chester, UK

Re: The matchless lives !

Post by clanger9 »

Sorry, I wasn't very clear: the points cam & advance mechanism is bolted onto the end of the camshaft via a taper. If the points cam isn't aligned "correctly" with the camshaft, then the points plate adjustment holes don't line up like they should.

To fix this, you have to set the engine 1/4" BTDC, take bolt (000012) out & pull the points cam assembly (043114) off the end of the camshaft (042090), rotate it so it looks like Fig. 5 and fix it back on.
points cam.jpg
timing.jpg
initial setting.jpg
PS: you don't need to use a special puller like it says in the manual. You can improvise a hammer puller with a big socket, a flat washer and one of the long 1/4" retaining bolts that hold the toolbox covers onto the frame. The toolbox bolts are the same thread as the one in the advance mechanism, so it screws straight in and they're long enough that you can slide a nice heavy socket on there.
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1989 Moto Morini Dart 350
1993 Ducati 750SS
ChrisTheChippy
Member
Posts: 274
Joined: Wed Feb 07, 2018 12:02 am
Location: Essex

Re: The matchless lives !

Post by ChrisTheChippy »

Hi clanger
Thank you for the tip re removing the weights . I guess I didn't make a very good job of describing the problem .
I did remove weights from the tapered shaft and with piston set at 1/4 BTDC on firing stroke it didn't seem to matter where I positioned them I just couldn't get enough clearance to get points just separating . I tried for hours and only as a last resort decided to file out and elongate the slots a bit .
Bike then ran .
This is the reason I asked the question in my first post does the points backplate differ on the 350 ? Have I got the correct backplate ?
Thanks for your help and input thus far great to have this forum .
Cheers Chris
ChrisTheChippy
Member
Posts: 274
Joined: Wed Feb 07, 2018 12:02 am
Location: Essex

Re: The matchless lives !

Post by ChrisTheChippy »

Hi
Just did a bit of research and the ignition timing for later 250 s was 3/16 BTDC . I wonder if points backplate was redesigned ? for the late bikes and this might be the reason that I could not get enough clearance ?
Maybe it's the later backplate from the Csr ?
I noticed there were lots of different mark's scribed on the cases probably from Po s attempts to start it ?
350 has 1/4 BTDC so probably the same backplate as 250.
It might help someone else with similar ignition timing problem .
Cheers Chris
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clanger9
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Location: Chester, UK

Re: The matchless lives !

Post by clanger9 »

Oh, I see! You're talking about the points gap!
Yep, same here: the new sets of points you can buy seem to be a bit fat and you're right at the end of the adjustment to get the specified gap. I left my slightly narrow as this doesn't do any harm...

Just to clarify: you do realise that you set the points gap first to 12 thou? (with the points fully open i.e. resting on the high part of the cam). Then you rotate the backplate to set the opening point to 1/4" BTDC (or 3/16" if it's a high-compression CSR) with the bob-weights set to full advance i.e. propped open. Apologies if this is teaching you to suck eggs - for such a simple ignition system they made it a right faff to get it set right...

There's no difference between 250 or 350 parts. The only change they made that I'm aware of is they backed off the timing to 3/16" for the 1965- 9.5:1 250 CSRs. The (slightly scary) 10.5:1 CS needs even less and will likely be unhappy on modern fuel whatever it's set to.
1989 Moto Morini Dart 350
1993 Ducati 750SS
ChrisTheChippy
Member
Posts: 274
Joined: Wed Feb 07, 2018 12:02 am
Location: Essex

Re: The matchless lives !

Post by ChrisTheChippy »

Hi clanger
Yes that's it . Couldn't get the points to just open with full advance of the weights . Whatever I did there wasn't enough room in the backplate slots to get the points to just open at 1/4 BTDC . Yes I am aware points should be set to correct gap before setting ignition timing . Grew up with battered old bikes and cars so have done a bit of engine work ( and bodging :D ) in my time . We had too, just to keep them going .
Probably only had to file about 1/32 out of the slots but that was enough for the bike to run .
I absolutely don't mind anyone pointing out correct procedures to do any job remember the debarkle with the Kickstarter ! Never hurts to be reminded because you can't always see what's right in front of you .
Maybe our discussion will help someone else to solve the same problem .
Thanks for your input and help with this project .
Cheers Chris
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