1955 18CS Drivetrain Rattle

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
jim501
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1955 18CS Drivetrain Rattle

Post by jim501 »

quote:
quite right, the rattly ones are often the fast ones


The rattly ones are so loose and sloppy there are no losses due to internal friction.

Things are so far out of tolerance, they rarely meet.

Bolt a 3" diameter breather pipe to the crankcase to look after the piston blowby and you could have a rocket ..


Don't rebuild it. You'll only be disappointed. It'll be quiet and boring.

cheers
jim
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TommoT
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1955 18CS Drivetrain Rattle

Post by TommoT »

quote:

Still im wondering if anyone in the club have tryed new cams and how they sound compared to some with 50-years of hard work in them.

Regards
keje?


Keje, 2 years ago my G80 engine was finally treated to the new bigend and various other bits'n pieces it had been wanting for so long. During the rebuild I decided to spend money on new cams and a timing pinion too. Mostly because I had the opportunity to use slightly sportier cam profiles from an AMC guru here in Denmark. I can honestly say that it did nothing to remove noise from my engine, which was never bad anyway.

Except for the clicking noise from the bigend the major sources of noise have always been the piston, the valve gear and the transmission. Not the gearbox (B52), which in my case has been the most reliable and flawless part, still providing slick silent shifts. The piston noise has mainly been due to a bad batch of Italian GPM pistons; the valve noise due to improper fixture of valve trays, allowing the springs to hit the rocker box cover; and the transmission due to incorrect set-up on my part, involving chain alignement and clutch issues.

So in short, changing cams may not be a noise abatement cure, but it all depends on the other parts in your engine.

On the timing issue can anyone tell me what AMC's considerations have been for using a 36 degrees BTDC inlet opening figure on the G3 as opposed to 18 degrees on the G80 (figures for 1956)? Is it because the 350 was intended to be a little more lively/revvy and the 500 to be more the staid tourer?

Let's hear how you get on!
TommoT

Ride Your Motorcycle As If Your Life Depended On It - Cos' It Does!
56G80S
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1955 18CS Drivetrain Rattle

Post by 56G80S »

Keje

Probably no help at all, but I put a piece of solder round the camshaft axle, screwed the cover up, unscrewed it and then used the depth of the squished solder as a guide to the shims necessary.

JDB
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Biscuit
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1955 18CS Drivetrain Rattle

Post by Biscuit »

Where are you looking Tom? Just looked at the AJS specs. for 1956, and they are the same, 36 Degress BTDC.



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keje
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1955 18CS Drivetrain Rattle

Post by keje »

Tom,
The engine is rebult and in perfect order I can assure you, the only thing that has not been messed around with is the cams.
I have decided to just let them be, the bike runs like a bat and with a straight pipe I will not here the rattle!
( "Stigs motor" has done the renovation of the engine, and he has the best reputation concerning engine jobs here in Sweden)
One thing that worries me is that the bike consumes sparkplugs in a hurry!... checking it out just now.

JDB!
Thank you for the tip.
During the winter I will surely try to fix the chimming your way,
Thanks!
Keje
SPRIDDLER
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1955 18CS Drivetrain Rattle

Post by SPRIDDLER »

Have you checked whether the light goes out in your fridge when you shut the door?
Blimey, I don't know how you all manage to sleep at night.
If it doesn't stop you grinning, leave it alone.
My G3LS has rattled nearly 8000 miles this year, over the Pyrenees and through snow, fog, 40 deg C and five grab-a-grannies (on multigrade - easier to get 'em started) and I'm still smiling in spite of shredding my jacket and boots when a wasp flew inside my helmet two weeks ago and sent me sliding down a lane. Haven't managed to get my leg over yet but hoping to get out tomorrow, now that I've straightened footpegs, levers, forks, headlight and front mudguard, and the splint has been returned to A&E.
Still grinning.
'There is a tide in the affairs of men
Which taken at the flood............'
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TommoT
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1955 18CS Drivetrain Rattle

Post by TommoT »

quote:
Where are you looking Tom? Just looked at the AJS specs. for 1956, and they are the same, 36 Degress BTDC.


...ahemm, just checked again, there must be an error in my 1956 handbook, but mind you this is the Matchless version, so it may differ from the AJS equivalent. The same figure makes much more sense...
TommoT

Ride Your Motorcycle As If Your Life Depended On It - Cos' It Does!
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keje
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1955 18CS Drivetrain Rattle

Post by keje »


Im being called a lier, talking to the youngsters saying that the engine, transmission and gearbox is fully restored and the strange noises is just right for this ancient bike.
Forget the rattle , just listen to the sound of the pipe I say!
That seems to do the trick.
And look, no oil on the pavement either!

Regards
Keje
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