1965 Matchless G15-CS


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Hey, all—my second bike here, following on my Royal Enfield adventures. Originally wrote about picking it up way back a few years ago at https://www.dotheton.com/index.php?threads/1965-matchless-g15-cs.66578/, and have cross-posted this latest info on AccessNorton.

So I had original thread over there about my initial attempt to get it running, tapping into all the expertise of the members there. (https://www.accessnorton.com/NortonCommando/matchless-g-15cs-get-it-running.21369/). It kind of lost focus, and I figured I’d start another, more concise thread with some updates.

Long story short, obtained the bike from the original US owner (friend of mine) in 2016 while I was living overseas; he saw the work I had put into my Royal Enfield (my first bike) and thought I’d be a good next caretaker, which meant a lot to me. He had conducted what he termed a “redneck restoration,” including the paint job, in the mid-90s. Ran when parked…but it had been a while. Due to living and work situations, it’s been hard to get to a place where I could work consistently on it.

As to why it's here in the "dirt" section...the G15-CS is a hybrid of a Norton Atlas engine with a Matchless/AJS frame and transmission, intended as a factory bike in the style of the California desert racers. (Sold with both Norton and Matchless badges and nomenclature...identical bikes aside from the tank badge.) It’s got of legend surrounding its creation, possibly having been mocked up in the US as an actual race bike then picked up by the factory for production…or, according to some seemingly less-reliable speculation, simply cobbled together from off-the-shelf parts during the consolidation of Britbike companies under AMC. Either way, it’s a pretty massive engine in a pretty small, stiff frame, and now that I have done some shakedown rides, I can vouch for how well it handles.

What I saw before I got the bike:

Picking it up….first view in the garage.

Loaded[/url] by https://www.flickr.com/photos/185106507@N04/]Mick Doul[/url], on Flickr

Got home and got full approvals for the acquisition

Then got to work

Off the bat, I found the magneto wasn’t working, so had that re-done with the Brightspark Easycap replacing the old Lucas paper capacitors...this puts the more-reliable modern capacitor in a place you can reach, and deletes the old school cap way down in the guts of the mag body.

The clutch hub was really notched up, and it didn’t seem cost-effective to try and clean it up, so I replaced it. The clutch pressure plate stripped in the center adjuster while I was working on it, so I put on a new, machined repop replacement and some barnett friction plates.

The carb slides were also sticking like hell, so I had them sleeved, then I rebuilt with new jets and gaskets.

Over an extended period of time, I also installed a reversing cam plate in the transmission so it would match my other bike, which is a right-hand, 1-down pattern. Had the Ceriani shocks rebuilt by a guy Irk Miller referred who’s into that stuff…no one else would touch them, and they appear to work well.

After finally getting it timed properly so it ran on both cylinders, I found the primary was a leak-fest. After multiple attempts to seal it, I installed a Newby belt primary, which was inevitable since I have one and love it on my Enfield. With both bikes, being able to access/remove the primary to get to other stuff without having a wet mess and constant gasket re-fitting was as much a motivation as performance…just wish I’d have ponied up to do it before fixing up the original clutch. I know I could have dressed the gasket surfaces, but it was just a mess I hated dealing with, and the Newby clutch is so much better.

Newby setup snap; you can see the access I cut into the rear cover to get to the magneto more easily, which is going to be a huge help...it will be closed off when the front cover is on, however:

Full Install report here: https://www.accessnorton.com/NortonCommando/newby-clutch-installation-report-g15-cs.29138/

I have found that the swingarm seems like it’s spaced too widely (https://www.accessnorton.com/NortonCommando/g15-cs-rear-wheel-spacer-issue.28979/#post-443070), but after a struggle with my original speedo drive which led to replacement with one of the British-made repops, I just tightened it down. Now it’s rolling without a hitch, so I’m going to leave well enough alone there, for now.

The tacho was also breaking every cable I put in it, so I think that’s due for a servicing. Haven’t yet sent it off yet, but should soon. Was focused on functional items first.

So here I sit now…

I need to do some minor cosmetic work, get the brakes optimized, and get it registered for the road and give it some more thorough shakedown rides, and also get into the forks to see what awaits me there. Previous owner said they had the typical top-out issues endemic to Roadholders, so I’m planning on doing the conversion described on the JSM Motorsports site (https://jsmotorsport.com/technical-fork-damping-sleeves/) assuming what I see inside the fork matches what the site describes. Was considering changing the solid metal fork shrouds out for the original flexible boots, but since the bike is about to be put up for three years in the spring, I’ll wait on doing that till I have the bike back in hand, and might put some of the JSM turcite bushings in at that point too.
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Thanks, man!

This week, I worked on getting a more finalized spacer for the primary rather than my arts-and-craftsy red rubber strip. (The Newby belt arrangement requires the outer cover to be moved from the stock position...) So, I got a damaged inner primary cover off Ebay cheap, then got jiggy with the sawzall...

Then took it to mill down the rim to 3/8" and will install for a more rigid, less-obvious modification.
Yes! Seems inline with everything I've heard about english bikes :D
You know, pain in the ass, bad electronics, leak like a sieve

And kinda pretty, and intriguing even with the bad teeth...accent that's alluring at first, but may grate later on...

(Who do you know who's struggled with Britbikes, tho?? o_O )

Electrics on this are surprisingly good, though, given the age and hardening of the wires. The AC from the alternator is only used for the lights. The magneto...itself a huge pain in the ass in its own way...does all that ignition duty.
Glad you posted it up here man. I like the new primary spacer mod. I'm in.

Thanks, man!

I just had to take a little more material out of the dowel and screw holes to make everything fit easily by hand; didn't want it to become a struggle with the relatively fragile piece down the road and possibly bend something, plus I cleaned up the sharp edges left by machining.

I also opened up the hole in the backplate where the wires pass through a little more, and also flap-wheeled that to super-smooth. The way the cutout is designed, I no longer have to fish wires and connectors out through that stupid hole...it's open to the top when the cutout is removed, and trapped in place in the little cavity I left once I put everything back in place.

Drilled some little drain holes, too, since it's not weather-tight.

Lastly, I need to take threads off the forward chaincase plug so that they don't interfere with the belt. Gonna mark the position it's in when it's tight and just grind away what little is needed for clearance.

So I'm here now, and it's exciting!
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Damn thing even has air filters now. The Uni sock filters are a lot less cumbersome than the stock filter, which is a flat, pig-iron cage containing a foam element right at the carb mouth. So in this case, pods are a decided improvement...

Another solid shakedown ride; no one to shoot video of it in motion tho. Atlas engine has balls for days. Brakes, on the other hand...yeep. That SLS front could use some more oomph. Some high-zoot pads and a new cable should help...the one on there is too long (per original owner's notes) and I run out of adjustment trying to tighten it up.

Iiii've beeeen woooorrrkinnngg on sussspppeeennssion, all the livelong day...

Goal was to get into the fork, inspect internals, and install a kit meant to cure some of the top-out woes endemic to the Roadholder fork. The G15-CS, however, has a modified Roadholder and the purveyors of the various kits were unable to tell me exactly what I'd encounter and what I'd need to make it better. Previous owner had warned me that the top-out was really harsh and encouraged me to make the mods #1 on my list. Given that I'm waiting for a registration and some parts, figured now was as good a time as any to dig in.

Getting into the fork was a little nerve-wracking. I know it's a simple design, but the way things fit together is often problematic on anything British. Fork fits to the top crown with a taper...why bother with simple things like clamps?

Ultimately, one leg came off easily and the other needed some encouragement, which led to some mashed threads which let to some time with a file, a wire wheel, a carbide bit, a cold chisel, and the top cap in a vise and me turning the leg on and off it slowly using a screwdriver through the oil holes. This is why I am always apprehensive about digging into something new on this thing...ugh.

So once I had the top cap threads rehabilitated, it was time for the modification kit. The mod kit was simple: tap 4 existing small holes in the stanchion to 6-32, plug with provided set screws and some bearing-retainer loctite (or JB weld or other goop of great permanence), then slide on some aluminum sleeves to sit below the top bushing. The sleeves blank off the oil hole at the right time in the fork stroke to (somehow) result in a hydraulic cushion on topout. I also used some needle files and a dremel flap wheel to smooth out some snags on the rim of the existing oil hole, which tended to catch the aluminum sleeve.

I'm not honestly sure about the exact oil flow in the fork in use; the "plunging damper" arrangement is something new to me, and there's oil passing between the slider and the stanchion aside from what's going on in the damper tube. I almost wonder if the brass static "valve" and the damper cup on top could be replaced with a shim-stack arrangement of some sort...hmmmm... If it could, however, I bet the Norton racing community already would have thought of it; even Racetech told me they couldn't do a cartridge-emulator with this style of fork. (I have one of the emulators in my Enfield fork...tasty and easy...)

There's a bottom-out remedy that's similar and normally comes as part of this kit, but the damper tubes on the G15-CS won't fit these collars. Nor does it seem to need to; the oil hole on the damper tube seems to be in the right place (above the apex of the taper) that the kits relocate it anyhow. If I have clanking on compression, I'll re-visit it.

So it all sits here, awaiting a few more small parts...had to mutilate a drain plug to free it, etc. In the meantime, I may try some experiments with the damper to see if it's doing the right things. Or maybe I won't...we'll see.

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Kit I used was from JSM Motorsports. Jim, the owner, was helpful and knowledgeable...


You can see the differences between my fork and the stock Roadholder if you compare his tech notes with my photos and description...for a riveting time, let me tell you.

I wanted to put in his turcite bushing kit, too, but for now, I'm just testing the major modifications...I will have to store all my bikes for the next 3 years starting in May ( :confused: ) so I'll do stuff like that on my return; probably lose the metal fork shrouds for the original-style fork boots, too.
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Thanks for posting this up man. I know my forks should get this treatment but I haven't begun the homework. Great job with pics and documentation.
No worries. I'd never have gotten to this point on either the Enfield or the Matchless without the help from DTT and elsewhere.

The P-11 forks are a Matchless model, not the Roadholders, far as I know, but the other Norton forks you have should take the kit without issue. (Needing the treatment on the taper portion that mine didn't, closing off any holes at the base and putting a single smaller one higher up on the bump stop...) You can accomplish the same as the aluminum sleeves I got by using a chopped tophat bushing, and even better one that's had the center relieved to lessen stiction. Tons of stuff on the Internet and a few articles I can send you.

In the meantime, I've tried testing the damper by cycling some fluid through; Jim from JSM had some restimated times that it should take to compress/extend by hand for his preferred levels of damping. Decided to close off one of the holes to increase compression damping, as there's very little, even with 20wt. Kiley's going to weld it shut for me over the holidays...I tried brazing a plug in myself using a propane torch, but couldn't get it hot enough for the rod I was able to buy at Home Depot.

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So it occurred to me that the clutch is running fine now, but as the plates wear, I'll have slippage like I did when I first installed it...the pressure plate was resting on the transmission mainshaft. I cured it with a little grinding on the pressure plate, but that clearance will go away as the clutch pack thins out.

Therefore, I bit the bullet while the fork was off anyhow, and did some in-situ surgery to better meet the first half of Bob Newby's instructions when I asked him about my clutch slip: remove 2mm from the mainshaft.

Avert your eyes now if you can't stand lazy, amateur hackery...I know the proper solution would be to disassemble the gearbox, put the mainshaft on a lathe, and turn it down. But since there's nothing actually touching the end of the mainshaft, I figured it only had to be roughly square. My only concern with the end shape, best I could see, was ensuring the smooth, snag-free operation of the pushrod. Next time the transmission is apart, I'll probably go ahead and get it touched up on a lathe for propriety's sake.

First, I covered the primary like a good operating room (or a Dexter kill scene...) using some foam packing sheeting pressed over the mainshaft. Then I used a combination of Dremel cutting wheels, carbide bits, and flap wheels to remove the requisite material, re-chamfer it, and smooth it all out. Going slowly and using my caliper's depth gauge helped me get it roughly even while working freehand; the flap wheel largely evened out the imperfections and made everything nice and glassy-smooth.

However, the shortening of the shaft led to another issue...in clutch engagement, the ceramic ball I had on the end of the pushrod arrangement would now stand fully proud of the mainshaft, pinned against the adjuster screw. Though it's held in that position against six springs, it made me uneasy. There was still a potential for it to somehow slip out. So, I went to follow the second half of Newby's instructions: grind the pushrod end to a "bullet shape."

To do this, I set my drill up on the workbench with a clamp, with the rod in the chuck, and spun it while I worked a counter-rotating dremel flap wheel to round out the end, periodically stopping to test-fit it against the pressure plate adjuster screw. It only took two or three fittings before it was perfectly shaped.

Then, I attempted to re-harden the pushrod by heating to glowing with a propane torch, quenching in oil, and re-tempering with the torch till I got a blue sheen on the outside. (Per WikiHow instructions...) I've never done that before, and do hope I got it right. I figure I'll check for wear periodically and make a new section if I have to. (Any input welcomed!)

Fits perfectly.

Also got my tach back in record time; if you need work done on classic Smith's instruments, give Mark Bohman a call at 513-367-6402.
Interesting fork design. Essentially it is an early cartridge design which is why Racetech don't have any emulators to fit. You could look at any modern cartridge and see how to adapt them to work in your forks.

Maxton in the UK are experts at that sort of upgrade using their own cartridge design, but you might be able to adapt say a GSXR 20mm cartridge to fit and that could be a huge upgrade.
Interesting fork design. Essentially it is an early cartridge design which is why Racetech don't have any emulators to fit. You could look at any modern cartridge and see how to adapt them to work in your forks.

Maxton in the UK are experts at that sort of upgrade using their own cartridge design, but you might be able to adapt say a GSXR 20mm cartridge to fit and that could be a huge upgrade.

Yep, there's no physical way to mount an emulator. The adaptation of a cartridge is something that could be cool, but that'd be way in the future. Thinking a dirt bike cart, maybe? Lots of things to consider there. But the forks' external springs do give a lot of space to work with, internally.

The idea of a shim or two instead of the little damper cup on the rod seems intriguingly simple, too...but like I said, if it worked I'm sure someone would have done it.

Someday I'll dig into it more, not now tho! Just gonna get it running as it stands for the moment.
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