G11 top end off for the first time

Information relating to the Matchless G11 or AJS Model 30 600cc twin
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clive
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Re: G11 top end off for the first time

Post by clive »

a loose valve guide probably means having an oversize one made, or it may be cheaper to pick up a second hand head and keep the old one until the cost of making the oversize valve versus the cost of a head makes it useable again !
clive
if it ain't broke don't fix
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iansoady
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Re: G11 top end off for the first time

Post by iansoady »

I would have thought any small machine shop could make a guide as they're hardly complicated. Phosphor bronze or cast iron round bar are available from Mallard Metals etc.

I could probably even make some myself.......
Ian
1931 Sunbeam Model 10
1999 Honda SLR650
Various
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Re: G11 top end off for the first time

Post by Various »

Right, spent a few minutes in the garage and can now confirm that the LH exhaust valve guide is loose in the head and slightly oily, it's not falling out but is easy to turn by hand. So that needs doing.

The valve seats are reasonably pitted (especially the exhaust), so they need grinding in to improve matters. The cylinder head itself has seen some action at some point in history but it has always performed well for me so will stay in use. The valves themselves look good.

The oil level in the primary chaincase is exactly as it was when I put the oil in about 1000miles ago, so it doesn't seem to be throwing oil in there. There was some water in the oil, presumably condensation (although my last ride was about 70miles). I dropped the sump plug out and about 200ml of oil came out, I last rode the bike about 2 weeks ago and it does have an anti wet-sumping tap on it. I always check the oil return when I go out, and have never had any concerns about the return flow.

The crankcase joint looks a bit grubby, I would expect an oil leak from there to have cleaned it up.

Next I'll have a look at the RH cylinder and then I'll know what I'm dealing with in total.
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1608
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Re: G11 top end off for the first time

Post by 1608 »

I have bought over-size guides for my single, if memory serves, from T&L Engineering 01234 352418. You could make enq's re same for the twin. As far as I know the club don't supply them. You could try Russels, AMC spares or perhaps further afield with those advertised in OBM.
Try this route before having any made, its cheaper.
Various
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Re: G11 top end off for the first time

Post by Various »

Thanks for the clues on where to go. My wife is cleaning the bedroom so the cylinder head is in the oven right now and should be done before she comes down, this should help to drop the guide out and then I'll start making enquiries.

Thanks to the reading in the Archives I found out about the circlip holding the guide!
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