500cc - weird engine number

Information relating to the Matchless G85 500cc Heavyweight, AJS 7R, Matchless G45 and Matchless G50
MG
Posts: 24
Joined: Sat Jan 01, 2011 4:21 pm
Location: Niederoesterreich AUSTRIA

500cc - weird engine number

Post by MG »

Hello gents!
I recently acquired this 500cc competition engine, with a very weird, but apparently unmolested engine number (see links below for pics).
Anyone got a clue whether this is a factory number or what it could be?
As luck would have it, a mate of mine has a G80CS (bitza) with a replacement competition engine and an engine number of the same type, only a good hundred units earlier (SU/fivethousandandsomething). You might have noticed that some fins on the rear of the barrel, below the carb, have been cut off, and the barrel on my mate's engine looks totally the same. So that could have something to do with the frame they have been fitted to. Did AMC sell unstamped engines for racing to go into third party frames?
Not really important for me, I'm just curious...
Cheers and all the best, Markus

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engine_pic2
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John Jarrett
Member
Posts: 438
Joined: Wed Oct 12, 2005 10:45 pm
Location: MIDDLESEX UK

500cc - weird engine number

Post by John Jarrett »

I cannot answer your question, however, I do have an interest in the answer as I have a 1962 G2CS with the same SU prefix rather than the normal year designation, so it isn't just the heavyweights that have that stamping. The common thread so far is that they are all competition engines. Hope someone can shed some light on the SU designation.
Kind regards
John
242017
Posts: 300
Joined: Mon Jan 01, 1990 12:00 am
Location: HASLEV 4690 DENMARK

500cc - weird engine number

Post by 242017 »

Its a motor sold to the Rickmans for use in a Rickman Metisse
The SU stands for "Single Unit"
It should be a norton pump engine around 1964/65
Hope that this helps
242017
Posts: 300
Joined: Mon Jan 01, 1990 12:00 am
Location: HASLEV 4690 DENMARK

500cc - weird engine number

Post by 242017 »

The cut off fins at the back were done as so the barrel would fit the Matchless g85cs which had the oil tank behind the motor
MG
Posts: 24
Joined: Sat Jan 01, 2011 4:21 pm
Location: Niederoesterreich AUSTRIA

500cc - weird engine number

Post by MG »

Thanks for that, nice to know what it is!
Yes, it has a Norton type oil pump.
Cheers!
242017
Posts: 300
Joined: Mon Jan 01, 1990 12:00 am
Location: HASLEV 4690 DENMARK

500cc - weird engine number

Post by 242017 »

Dear MG,
I found out today that these competition engines stamped SU were also sold individualy in Scandnavia by Matchless and a few AJS examples were also sold.
Did you get the motor at a good price?
MG
Posts: 24
Joined: Sat Jan 01, 2011 4:21 pm
Location: Niederoesterreich AUSTRIA

500cc - weird engine number

Post by MG »

Hmm, unfortunately the timing cover is missing, and there is no other visible hint whether it was branded "AJS" or "Matchless".
The price was more than reasonable really, I bought it together with the Lucas wader mag and a BSA Goldie s'arm frame it had obviously been fitted to (heavily modified for sidecar racing, but incl. the BSA RRT racing gearbox). It's all in a bit of a state, but nothing that couldn't be fixed (I haven't opened the engine yet though...).
I might buy the G3C frame from a mate of mine to give it a proper new home
Thanks a lot for your detective work! Interesting really, what sort of frame could they have been fitted to in Scandinavia?
Cheers again!
242017
Posts: 300
Joined: Mon Jan 01, 1990 12:00 am
Location: HASLEV 4690 DENMARK

500cc - weird engine number

Post by 242017 »

From the shape of the timing cover you can see if its a Matchless or AJS.
I think that they were probably put into Metisse frames bought seperatly..The engines are heavy old lumps and need a substantial frame....Good luck finding the gears racing with a RRT gearbox...Ive only ever found a whole bunch of Neutrals....The late Amc box stamped MA is what you need...
Timing covers were sometimes just made out of a piece of alu sheet back then
MG
Posts: 24
Joined: Sat Jan 01, 2011 4:21 pm
Location: Niederoesterreich AUSTRIA

500cc - weird engine number

Post by MG »

Good point on the shape of the timing cover, once again!
Not the best pic, but it's all I have available atm. That makes it a Matchless then:


quote: Timing covers were sometimes just made out of a piece of alu sheet back then
Such is the rocker box cover on that one.

Thanks again!
242017
Posts: 300
Joined: Mon Jan 01, 1990 12:00 am
Location: HASLEV 4690 DENMARK

500cc - weird engine number

Post by 242017 »

Jeps Thats a Matchless
The Swedes did make various frames back in the sixties for various motors..Sune Olsen was one such maker and his frames are sometimes available today unused
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