AJS 18S valve guides (again!)

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
Locked
andyblue
Posts: 36
Joined: Thu May 01, 2003 1:00 am
Location: WEST SUSSEX UK

AJS 18S valve guides (again!)

Post by andyblue »

Hello team

A while back I asked for help with the valve guides for my '55 18S which after having new ones fitted were not tight enough in the head and so had slipped down until the exhaust valve was held off its seat.

As advised I fitted the little circlips to the guides which were a later mod ('56?) and also I nickel plated the exhaust valve guide to build up the diameter and give a tighter fit. So far so good.

The trickier bit seems to be modifying the underside of the hairpin valve spring plates to give clearance for the guide circlip. These plates are b***** hard. I have been grinding them with a selection of small spherical shaped grinding stones in the old bench drill. Trouble is I have nearly gone through the whole thickness of the plate now and it still wont sit flat on the head over the guide due to the circlip. If I go any further and enlarge the diameter of the hole that seems like bad news as the plate can then slop around on the guide. Any ideas?

Presumably later spring plates had clearance for this circlip. Does anyone know the part number for these later ones and can you get them from the club spares or Russells, in case I mess my old ones up completely?

Frustratedly.....

Andrew

User avatar
Biscuit
Deceased
Posts: 3924
Joined: Thu Jan 01, 1998 12:00 am
Location: KENT UK

AJS 18S valve guides (again!)

Post by Biscuit »

Fitted a circlip to my '54 head with no problems. I hesitate to say this, but have you got the dimple ( or is it a peg) located in the hole on the cylinder head spring seat? This stops the spring rotating.



andyblue
Posts: 36
Joined: Thu May 01, 2003 1:00 am
Location: WEST SUSSEX UK

AJS 18S valve guides (again!)

Post by andyblue »

Hi Alan

Good point but yes, I am lining up the dimple/peg on the underside of the plate with the corresponding hole in the head.

I can only think that yours must have been fitted with the later style spring plates which already have clearance for the circlip.

The AJS singles maintenance manual I got from the Club tells you to fit the new style plates but also says you can use the old style plates if you grind clearance for the circlip from the underside. This 'aint as easy as it sounds hence my enquiry.

So if anyone knows if these plates with circlip clearance are available, or has a couple of spare ones kicking about I would be very pleased to hear from you!

Andrew

User avatar
Biscuit
Deceased
Posts: 3924
Joined: Thu Jan 01, 1998 12:00 am
Location: KENT UK

AJS 18S valve guides (again!)

Post by Biscuit »

You could be right Andrew, I did take the springs from a later head which was wrongly fitted to the bike.



Locked