G80CS... and the saga continues

Information relating to the Matchless G85 500cc Heavyweight, AJS 7R, Matchless G45 and Matchless G50
Member
User avatar
Posts: 464
Joined: Wed Mar 05, 2014 4:21 pm
Location: Oxted, UK

Re: G80CS... and the saga continues

Postby Peter Morris » Tue Sep 25, 2018 8:29 pm

ajscomboman wrote:
Lap the head


What is the correct procedure for lapping head/barrel on comp bikes please Rob, same sort as style as lapping valves?, My G3C needs doing, have a problem with oil in the cylinder. I understand that a head gasket should not be used... even though I have one :? ... can't help thinking it's a valve/guide problem though (it's had a new oil ring). It will be apart straight after the Ardingly AMC show so we'll see.

Member
Posts: 197
Joined: Sun Oct 25, 2015 8:19 am
Location: AUSTRALIA

Re: G80CS... and the saga continues

Postby Matchymarty » Wed Sep 26, 2018 9:24 am

Peter,
A lot of the guys don't lap the heads. Yes, they were meant to be lapped, (though I"m not sure about the long stroke) but according to posts on this forum (if you search for them), it's a painstaking long process.
I've been running a copper gasket on mine for as long as I've had it with no major issues there. The Short Stroke models are the ones that are more of a pain, as they are definitely meant to be lapped, as the o'rings for the push rod tubes at the top of the barrel are usually supplied in a thickness that does not allow for a gasket. I know, as I've just been through this myself!


Peter Morris wrote:
ajscomboman wrote:
Lap the head


What is the correct procedure for lapping head/barrel on comp bikes please Rob, same sort as style as lapping valves?, My G3C needs doing, have a problem with oil in the cylinder. I understand that a head gasket should not be used... even though I have one :? ... can't help thinking it's a valve/guide problem though (it's had a new oil ring). It will be apart straight after the Ardingly AMC show so we'll see.

Member
User avatar
Posts: 2403
Joined: Mon Jan 01, 1990 12:00 am
Location: HAMPSHIRE UK

Re: G80CS... and the saga continues

Postby ajscomboman » Tue Oct 02, 2018 5:26 pm

You can use a head gasket on both the long and shortstroke CS models even though the heads were originally just lapped in. To compensate for the gasket you have to use the correct thicker O rings other wise it'll just piss out oil. All the bits that are required are available from AMC Classic Spares.

Personally for a road going bike I'd use the gasket every time as you're not going to strip the motor as frequently as you would if you were using it as a true comp bike.

For the record Pete the lapping procedure is the same as you would do for lapping a valve.

Previous

Return to Competition / Racers

Who is online

Users browsing this forum: No registered users and 2 guests