G85CS possibility?

Information relating to the Matchless G85 500cc Heavyweight, AJS 7R, Matchless G45 and Matchless G50
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G85CS possibility?

Postby aljobo » Wed Dec 26, 2012 8:35 pm

By sheer good luck, I have acquired a NOS G85CS engine.
I have two alternatives : make a nice display base for it and enjoy looking at it; or make it a start point for a bike. Is the latter just a pipe dream, or could I succeed over time in getting all the right bits?
All opinions listened to.
Allan

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Re: G85CS possibility?

Postby clive » Wed Dec 26, 2012 9:45 pm

Well you can certainly make a bike whether or not its original. If you want a paper weight I will swop it for a nice (but seized) WD G3. Happy new year deciding what to do!
clive
if it ain't broke don't fix

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Re: G85CS possibility?

Postby 242017 » Wed Dec 26, 2012 10:46 pm

So what you mean Alan is that you have got a Matchless G80cs engine (with the norton oil pump) that was supplied to a Matchless G85cs bike ?
Geoff

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Re: G85CS possibility?

Postby aljobo » Wed Dec 26, 2012 11:40 pm

Yes, that's a way of describing it.
If a G85CS is a complete bike, then a G80CS is not an engine either (?).
My point was that I'd like to avoid just losing a precious new engine in a bitsa.
It really should become a part of a worthwhile project. Just don't know where to start.
But, if not, it can just as easily live on its own!
Allan

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Re: G85CS possibility?

Postby 242017 » Thu Jan 03, 2013 1:17 pm

You state the engine is "new"....so how new is that???

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Re: G85CS possibility?

Postby mdt-son » Thu Jan 03, 2013 7:41 pm

aljobo wrote:By sheer good luck, I have acquired a NOS G85CS engine.
I have two alternatives : make a nice display base for it <....> or make it a start point for a bike. Is the latter just a pipe dream, or could I succeed over time in getting all the right bits?


Third option: Sell it to me :-)
It would be interesting to learn how a NOS engine survived unmolested for nearly 40 years. Was it at the back of the Rickman Bros. workshop?

Geoff thinks it's a G80CS engine. The 85's were a bit higher tuned though. Some engines used in the Rickman scramblers even had special heads.

I can't recommend the venture of creating a G85CS Replica. Having collected parts during the last 15 years, i am still far from finished. Russell Motors had some parts 10 years ago, these are now all gone I think.
Major obstacles are at least fork yokes, petrol tank and engine plates.

My recommendation is to go for a Rickman chassis instead.

Regards, Knut

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Re: G85CS possibility?

Postby 242017 » Thu Jan 03, 2013 7:51 pm

Dear Knut,

There is NO difference between a norton oil pump G80cs engine or a G85cs engine....just the stamping on the cases...one was supplied to a Matchless G80cs and the other to a G85cs

Any work on the heads was done outside the factory..there are different castings but the heads are all the same for this model....

The Rickman Metisse was made for a triumph motor and so the inlet tract on many CS heads were welded up and bored directly to suit the frame....You cant just bolt on a straight inlet tube to a Rickman or Cheney frame using a Matchless engine

Motors to Rickman were stamped SU

"So many myths....so little truth"

Best Wishes Geoff

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Re: G85CS possibility?

Postby wilko » Thu Jan 03, 2013 9:54 pm

Just put it in any road frame and use it.

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Re: G85CS possibility?

Postby mdt-son » Thu Jan 03, 2013 10:10 pm

Hello Geoff and 'CS' fraternity,

All the best for 2013!

I have waded through the parts lists and found a few differences ... I thought there were more (?), like higher lift rocker arms and a different head;
it seems the G80CS got it's sibling's cylinder head during the '64 model year. You are therefore essentially correct, however:

028196 Piston, CR 12.5:1. Never fitted on series production G80CS, which had optionally: 026811, CR 12:1
023113 Axle, drive side. All later G80CS had p/n 026285 for alternator fitment. Yes, pre-60 CS engines w/out lighting had the short drive shaft.
NM25450 Oil pump. Series production G80CS: NM15522
030173 Oil pump worm nut. Series production G80CS: NM2076
032208 Oil discharge pipe. Series production G80CS: 024229
032205 Platform, mangeto. Series production G80CS: 030174

Because of these differences, the engines could not have been made in the same production batches.

Regards,
Knut

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Re: G85CS possibility?

Postby 242017 » Thu Jan 03, 2013 10:41 pm

The engines supplied to Rickman were the same as went into the G 85....The G80 could be supplied with the higher ratio piston and were...also the G85cs that were sent to the usa could also be supplied with both pistons and were if used for "desert racing" better off without that huge lump of a piston....good for holding doors open and thats about it....The oil pump changes occurred all the time..and were supplied to both motors...The factory scrambler of Vic Eastwood and Dave Nichol was called a G85cs,and
was made in and around Jan 1963....The first production of g85cs was in 1965....By then the bike had also changed in many details but not the engine

The engines were the same except for the stampings for all G80cs and G85cs motors

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