Head Gasket

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
mikeydpippin
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Head Gasket

Post by mikeydpippin »

A head gasket as suggested by the spares manual ( the copper gasket) won't fit my 1963 G80 500cc

Should it be 028100
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Last edited by mikeydpippin on Sun Jan 28, 2018 9:59 pm, edited 3 times in total.
Mike
JimFitz
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Re: Head Gasket

Post by JimFitz »

Hi Mike

Looks to me like you are trying to fit a head gasket to the cylinder base gasket position. This gasket should be a thin paper one.

The mating surfaces of the crankcase halves do not look right either - looks like they may be from different engines.

Jim
Too old to Rock and Roll but too young to die.

1952 G80 rigid, 1960 G12 DL / Watsonian Monza, 1954 G80S.
mikeydpippin
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Re: Head Gasket

Post by mikeydpippin »

Thanks Jim put gasket on wrong place guess I have right gasket wrong location, been in shed too long I reckon. edited post Thanks.

Your right the crankcases do look like there from different bikes, turning into a bodge this bike considering one owner from new, engine number removed, and over tightened and cracked alloy on oil inlet pipe.
What next, hopefully the crankcases will be ok..
Mike
SPRIDDLER
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Re: Head Gasket

Post by SPRIDDLER »

Mike, I hate to say this and I know the close-up photo exaggerates the mismatch of the c/case halves but if you go ahead with that you can probably expect to have an oil leak from the cylinder base. It's only a very thin paper cylinder base gasket.
'There is a tide in the affairs of men
Which taken at the flood............'
mikeydpippin
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Re: Head Gasket

Post by mikeydpippin »

Oh dear, probably explains why the engine number was removed, probably not a G80 half on the left side ( looking at photo)
Mike
alanengineer
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Re: Head Gasket

Post by alanengineer »

Were the crankcases an ebay bargain?
SPRIDDLER
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Re: Head Gasket

Post by SPRIDDLER »

mikeydpippin wrote:...........one owner from new, engine number removed, and over tightened and cracked alloy on oil inlet pipe.
Does the bike have a V5? Is the frame number still there and unmolested?
:?
'There is a tide in the affairs of men
Which taken at the flood............'
mikeydpippin
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Re: Head Gasket

Post by mikeydpippin »

No Nev,
Bought over the phone from scouser, told one owner from new, and it had been driven into shed in good working order but been off rd for 30yrs, since delivery have found engine numbers has been removed casting around oil return pipe cracked and broken (had that repaired) fork leg bolt hole casting broken (being filled in today and I will redrill and helicoil).
Original fuel tank rotted underneath (but I have a tank that will fit, but not the knee knocker tank).and now realise the crankcases are different, just hope the flywheels been balanced.
No V5 so will have to get age related, and apply for dating cert with frame number. (frame number readable and on frame)
Tinware all good though, and most bits there, and a bit of side to side play on connecting rod, but no up and down play.
Spoke to Steve, no chance of getting a G80 crankcase with engine numbers on, Steve suggested building as it is and sorting out any probs as and when they arise. May be able to get engine numbers stamped on it, but main concern is what to do with these crankcase halves,


Lesson learnt, Go see bike before buying it.. thought £700 was a steal.
Last edited by mikeydpippin on Mon Jan 29, 2018 2:51 pm, edited 2 times in total.
Mike
bob
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Re: Head Gasket

Post by bob »

I would be checking the main bearing alignment .
Guessing that originally the crankcases were machined as a matched pair , and they obviously aren't
MikeM.
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Re: Head Gasket

Post by MikeM. »

You could use a pair of G3, Model 16 or 18 if there are any available. My Twingle has G3 stamped cases even though it's a 500!
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