Performance upgrade info needed

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Janet
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Re: Performance upgrade info needed

Post by Janet »

SPRIDDLER wrote:Clip-ons and rearsets, plus a few strips of chequered tape, an empty silencer, thick white socks turned over my boot tops, white silk scarf and a Zippo lighter used to make me very fast indeed. ;)
Is this a case of "The older I get, the better I was"? ;)
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SPRIDDLER
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Re: Performance upgrade info needed

Post by SPRIDDLER »

Janet wrote: Is this a case of "The older I get, the better I was"? ;)
That may be so, Janet, but no-one ever overtook me in a dream :)
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Which taken at the flood............'
Mick D
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Re: Performance upgrade info needed

Post by Mick D »

Hi Steve

Judging from your post it seems like you are new the classic AMC machines - excuse me if I'm wrong, and if this is the case you have no reference point as to their performance.
I'm not suggesting you'll be blown away with neck breaking acceleration and braking but you may be surprised at the pleasure that can be had riding at 50's performance levels.
Yes your bike can be tweaked to deliver a little more power but nowhere near that of later machines. It will never compare handling and braking wise, so you will always be slower than them and you will be risking catastrophic failure coupled with substantial re-build costs and down time.
Why not rebuild it as per design and enjoy it - or at least give it a try before modifying it.

Regards Mick
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spookefoote1956
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Re: Performance upgrade info needed

Post by spookefoote1956 »

If you go too fast then folk won't be able to see you and you won't be able to see how gorgeous you look as a reflection in the shop windows! :D :D :D :D
Hail Joe Lucas ............ Prince of Darkness!
All my bikes are original........ to me!
"Creativity is your intelligence having fun" Albert Einstein
Andy51
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Re: Performance upgrade info needed

Post by Andy51 »

Hi Steve, I have a '54 18S fitted with scrambles cams and 8.5 to 1 piston, and no baffles in the silencer to allow the exhaust to flow freely. The performance improvement is noticeable compared with my '54 standard G80S, but on the debit side you lose a bit of tractability - it will not pull happily below 35mph in top, so all town work is in 3rd gear- and it makes a LOT more noise, to the point of being uncomfortable on long rides. I regularly ride at 60 - 70 mph and use the acceleration a fair bit, and the motor has held together without any problems. As for the brakes, they were rated as a bit marginal even back in the day, and time hasn't improved them! I am working on a 2 LS conversion at the moment, which should make matters a bit better. However, I have learnt from this bike and would probably not build it this way today. Where I live now (E Berks) the area is built up, roads are crowded and speed limits abound - I used to live in rural Wilts - and I get little benefit from the additional performance; the standard performance is more than sufficient for my normal riding. I don't know much about The Channel Islands, but my guess is that you haven't got many fast roads and will gain little benefit from big performance increases. Go with Pharisee's suggested mods by all means, but anything more will be wasted. There is also the problem of finding competition cams, they are rare and probably expensive. Hope this helps, Andy
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spookefoote1956
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Re: Performance upgrade info needed

Post by spookefoote1956 »

It is a well known fact that if you ride above 57mph your skin will begin to peel off your face. Please don't say I didn't warn you. :o
Hail Joe Lucas ............ Prince of Darkness!
All my bikes are original........ to me!
"Creativity is your intelligence having fun" Albert Einstein
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Martin.S
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Re: Performance upgrade info needed

Post by Martin.S »

How big a piston can you get in there?
MalcW
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Re: Performance upgrade info needed

Post by MalcW »

SPRIDDLER wrote: Clip-ons and rearsets, plus a few strips of chequered tape, an empty silencer, thick white socks turned over my boot tops, white silk scarf and a Zippo lighter used to make me very fast indeed. ;)
Back in the day I had Ace bars (remember them?) and a racing style dual seat that had that very thin padding that apparently mostly consisted of gravel. My only excuse is I was 18 at the time. Absolutely no faster; in fact it made journeys seem slower, mainly because it was so uncomfortable that you couldn't wait for it to be over. That lasted about a year, then the standard seat and bars went back on.

Malc
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Pharisee
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Re: Performance upgrade info needed

Post by Pharisee »

Martin.S wrote:How big a piston can you get in there?
Standard bore is 82.5mm. T & L Engineering can supply a +0.060" piston which would put the diameter up to 84.024mm. With a standard stroke of 93mm, the capacity would be 515.68cc

But I'm guessing that that's not what you're asking. If you mean what the highest compression ratio you can get... I don't know, sorry. :(
I'm from the Fens.... Gimme six.
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