AJS & Matchless Owners Club

I want to attempt changing the valve guides myself. I now understand the procedure is to heat up the head before attempting to drift them out - Is it right that these have to be removed thro' the head - i.e. into the combustion area?

normally you drive the valve guide out into the combustion chamber so that any build up on the lower outside part of the guide does not damage the fit. It there is a circlip fitted on your guide then you may have to drive it the other way a small amount first to allow the circlip to be removed. Use a drift that centres in the hole. Heating in the oven is best done when you are on your own, but in my experience you get caught anyway! I have done it so it must be fairly straight forward, although on a single head rather than two twin ones. Good luck

Thanks Clive. I've had this 1957 G11 in the garage, unused for ages. I bought it in 2002, initially did a rebuild, getting it rebored, big ends etc but never got round to sorting the head out ( on this model its split heads). Unfortunately the guy who did the bottom end for me didn't make a good job of sealing the crankcases as there is an oil leak behind the generator - where the felt filter is located. Plus, no matter what i do to the carburetor it the bike only runs for about 30 miles before the plugs foul up (hence why its stood there unused for so long).
Now i thought from the deposits on the plugs this fouling was fuel related, but now wonder if its actually more to do with the valve stems being worn.

So, I've decided to bite the bullet, and strip the engine down again to (try) and fix the oil leak and sort the heads out as I go.

melsajs wrote: Plus, no matter what i do to the carburetor it the bike only runs for about 30 miles before the plugs foul up (hence why its stood there unused for so long).
Now i thought from the deposits on the plugs this fouling was fuel related, but now wonder if its actually more to do with the valve stems being worn.

So, I've decided to bite the bullet, and strip the engine down again to (try) and fix the oil leak and sort the heads out as I go.

Does the bike smoke at all? you should really have plumes of smoke to foul the plugs that quickly with oil. your problems could still be fuel/ignition related, what grade of plug are you using?

If you do need to change the guides it will probably also be necessary to recut the valve seats.