Just viewed the photos and video of the ex-police G12CSR- most interesting! I recently bought a 1963 G12CSR rolling chassis- sans engine- to use to construct a 1963 G15/45 (750 cc twin). I have all the other pieces for that bike, but needed a 1963 frame with a proper number to be close to correct. I have another fully restored 1963 G15/45 to use as a guide, and the engine and frame numbers on that one are as shipped from Plumstead in December, 1962. The rolling chassis I bought has a frame number just 28 units different from what my second G15/45 engine number approximately calls for.

One note, which your G12CSR also shows: In 1963, AMC began using their "interim" rear hub on road heavyweights, a QD unit with a wider brake drum. In 1964 they moved on to use the Norton QD rear hub, which was a bit different. They used Norton forks, front & rear wheels and brakes on their larger "hybrid" road bikes to the end. 1963 AMC "interim" hubs are very hard to come by. Fortunately, I found one to use for the latest G15/45 project.

I was a bit surprised to find that my 1963 G12CSR rolling chassis had a conventional non-QD rear hub and brake, not the "interim" unit. Yours also has a conventional rear brake, so they must have done that on the '63 G12CSR's, at least. My chassis, your bike, and my restored G15/45 do have the proper G80CS-style Matchless 5-fin front hub, with wider brake shoes, which was also introduced to road heavyweights in 1963 as a braking improvement.

Best wishes on your restoration- Paul Allen, San Luis Obispo, California.

Hi Paul, sounds like you know a lot more about these than me, this is my first ever Matchless, but I have been told but my mate that did the engine for me pretty much the same as what you have said. This paticular model is rare as rocking horse poo here in AU at least.
For your interest the frame is A84488, engine G12 CSR 8952.

I am cleaning the tank inside this week so should have a first test ride later in the week. Hope I can remember that the brake pedal is on the wrong side:)

If you cn post some pics of your bike here.

cheers.chris

Hi Chris- Thanks for a prompt reply. As background on me, my first motorcycle came during my college years in about 1964- a 1957 basket case G80CS scrambler. I assembled it in my upstairs bedroom, and several college roommates helped me carry it downstairs one night. While they stood around with flashlights and a fire extinguisher, just in case, I tried to start a motorcycle for the first time in my life. It started on first kick, idled nicely, and I have been stuck on Matchless ever since.

Later I worked 6 years or so as a motorcycle mechanic, then got away from them to raise my family, while I worked 30 years for a local air pollution control district as air monitoring manager, then as their fiscal/administrative services manager. Now retired, I got back to classic Brit motorcycles about 8 years ago, and have been a member of both the UK matchless Owner's Club and the North American Section of AJSMOC for about that same time. I have learned a lot of good tech info reading their monthly newsletters, and have written perhaps 5-6 tech articles for both the US section club and the UK parent club over the years.

I now have four Matchlesses, each restored to show quality. They win awards, but unfortunately don't get ridden as often as I would like: a 1967 G80CS 500cc single; a 1966 G12CSR 650cc twin; a 1963 G15/45 750cc twin, and a "1967" Rickman Metisse MK3 with a G80CS 500cc engine, licensed for street riding, with total loss electrics and lights, since I don't ride off road.

The newly purchased '63 G12CSR rolling chassis I mentioned earlier has frame #A84092, but of course has no engine number. The frame on my complete '63 G15/45 is #A84121. Several years ago I happened to buy the bottom end of another '63 G15/45 engine just 2 units earlier than the one for my complete restored bike (#272 vs #270), so the "new" frame will serve well to assemble a second G15/45. Over the past 2-3 years, almost all of the further parts I need have materialized. Over the two years of production, AMC made about 220 G15/45's, virtually all sent to the US. Not sure yet whether it's a blessing to have two of those or not.

A tech note for '63 twins: Both the "complete" G15/45 engine and the partial one had the same problem, caused by reduced flow of oil to the bottom end and crankshaft. On the "complete" G15/45, clearance on the drive side con rod had opened up a bit, so the rod was loose on the crank. It surely made noise, which may be why it was parked before failing completely- a blessing. I had the rod and center main journals reground, and had the crank dynamically balanced when I rebuilt it.

The second bottom end I later bought consisted of crankcases, crankshaft, and con rods. It was very rough and had sat open on a dirt floor for perhaps a decade or two. The timing side crankcase had corroded badly as a result. I was able to find a NOS G15/45 timing side crankcase to replace the corroded one, and repair that damage when I rebuild the engine.

The drive side con rod on the second G15/45 engine had opened up excessive bottom end clearance in its earlier operating life, to the point of the rod hitting and wearing away the inside of the crankcase. Years ago, the owner had heli-arced that damage, reground the crank, replaced the rod, and returned the engine to service. Then, shortly after that, the same failure happened again. He took the engine out, took it apart enough to find out what went wrong, and when he saw the same damage again, he just left the engine in the dirt, in complete disgust.

When I got the bottom end, I found the felt oil filter, which crosses the engine in front, completely clogged and collapsed by pump oil pressure. The felt filter in the "complete" G15/45 engine was also very clogged, but hadn't yet collapsed.

What happens when oil flow is restricted by oil filter clogging and/or collapse in the 1963-era twins is oil flow to the drive side rod is lost first, so it fails first. This probably also happens
in other year model twins. AMC made lots of changes to the oil system on twins in the last 10 years of production, even increasing the capacity of the feed and return pumps in 1964 and later years.

But the real culprit wasn't pump capacity, it was owners not diligently cleaning that felt filter. At one point, AMC dropped the felt and just used a fine screen filter, but unfortunately that doesn't do much but keep the big chunks out.

Good oil filtration is essential for long engine life, and to minimize the chance that some metal contamination will cause quick failure. I thoroughly clean my engines when they are apart for rebuild, and wash and clean the cross-engine felt filter every time I change oil.

As added safety, on the '63 G15/45 and '66 G12CSR, I have added a Norton full-flow canister filter in the oil return line from the engine to the oil tank. I will do the same on the next G15/45. I modify the return line banjo fitting from the engine (the rear one), and solder in a new, longer length of 1/2" copper tubing. Before I solder that in, I have bent it in a fairly tight 180 degree arc with a good tubing bender, so it comes forward to the front of the engine. I make a bracket to hold the Norton filter body, positioned in the curved cavity where the generator was located before the alternator was used. Then I run the rubber return line back to the tank, bundled with the feed line as normal. For that matter, I also installed a Norton full-flow filter in the return line of the Metisse/G80CS. Clean oil is so essential!

Whether you choose to install a good filter in your oil system is up to you, but at the very least, don't ignore the factory felt filter in the front of the crankcases. Clean it OFTEN!

Matchless developed a bad reputation in the United States in the 60's for having "weak cranks". They lost a big market share as a result. I truly believe the real fault was owners not cleaning their filters regularly.

This response has gone on way too long. I would love to send a few photos, but am unsure how to attach them. If you have any tips, I can try that next time. Best wishes- Paul

Well I took the beast on it's first small test ride today, bloody aftermarket gaskets, blew the left head gasket within 1k, so made my own this time, will test that tomorrow.

BTW see here for loading images
http://auction.netbikes.com.au/vjmw.php?page=forum#bn-forum-1-1-744363701/8574/757429/show

Hi again Chris- On my '66 G12CSR, I blew out two composition head gaskets, one in the first 1K, the second (same side) at about 2K. This was despite careful re-torquing and repeated warm up/cool down cycles on the new engine. Evidently, aftermarket composition gaskets often have this problem. AMC used a composition gasket with embedded wire mesh, but no one makes these any longer.

So I made my own solid copper head gaskets, about 0.040" thick, I think. LOTS of work! Made four of them. Have since found a local source for them (in Arizona, USA- Copper Gaskets Unlimited, available online). I annealed my handmade ones properly, and they haven't given me compression blowout problems since, with another 800 miles on the bike. Solid copper head gaskets for twins are now also available from the AJSMOC Jampot Spares scheme in the UK, and can be ordered online by members or non-members.

I did recently develop another head gasket problem with my solid copper gaskets- an oil leak between head and barrel on one cylinder. Reading over the years in the Jampot newsletters, this is evidently the shortcoming of solid copper gaskets. I pulled that one head off, and drilled out the oil feed hole in the copper gasket at the top end oil gallery on that side, to accept a viton "o" ring that was about 0.010" thicker in chord than the head gasket. There isn't much meat left in the copper gasket at tight spots, but if carefully located, it can be done.

I re-annealed that modified but original gasket, and re-installed it. So far, so good. I won't do the same fix on the other cylinder until/if a leak develops there. It's possible that the Jampot Spares copper gaskets can be ordered with "o" rings already installed.

Oh, another note- I sprayed the solid copper gasket with a high-temp copper silicone sealer this last time- that might also help well with possible oil leaks.

Thanks for the info on attaching photos. I will try that soon, but this posting has gone on too long again. Regards- Paul

Yes we did the same O-ring method too, so far so good, I'll take the bike for a decent run in the near future to really test it. Will also do a small video and upload it here.
Thanks for the lead on the copper gaskets, they have a ebay store too which makes for easy purchase.

chris

Small Video of the Matchy in the garage.

http://www.youtube.com/watch?v=cBanaaFA4gs