Poor starting on G12

Biscuit · Post by **Biscuit** » Fri Jan 04, 2008 5:35 pm

Did you ascertain exactly what he was going to do?

Steve Dempster · Post by **Steve Dempster** » Fri Jan 04, 2008 5:45 pm

Fix it as far as I know!

Aside from being facetious - I don 't know. I tend to leave experts to do their thing - all I care about is that the thing works. Having looked round his place I can tell he is a pro - I used to work for a Lucas main agent in the 70's and recognised the test rigs etc (of which he has quite a few!) and also many of the Lucas boxes brought back memories! His collection of bikes is can't say any better than that and I'm afraid I slobbered badly but what the heck (and not a Matchie or AJS anywhere even.....)

Biscuit · Post by **Biscuit** » Fri Jan 04, 2008 8:15 pm

Re the difficult nut. You will need a lathe for this, or know someone who has.

Chuck a piece of .6" AF hex., drill and tap to suit your bolt and countersink ( I have seen all sorts of bolts in this location from Whit to metric, including one square headed bolt from a bedstead!)

Turn down to 7/16" for 1/4", part off the lenght of head you need, turn round in chuck, face off, chamfer and C/sink.

Drill the bottom hole of the mag. 7/16", insert the plain portion of the nut in the hole with a lick of Loctite, inert the bolt, with a spacer if necessary, tighten to ensure that the nut is pulled up hard to the flange.

This also works well for the rear dual seat bolts and the bottom gearbox nut, the one hidden behind the inner chaincase.

You now have a permanent nut, into which you just screw the bolt.Edited by - Biscuit on 04 Jan 2008 8:19:30 PM

Groily · Post by **Groily** » Fri Jan 04, 2008 8:56 pm

I'm intrigued by this bottom nut and bolt thing. The long-hex nut is common on many marques, either as original or as an intelligent mod by those not blessed with unnatural digital articulation. But my Mod 20 has a short (non-bedstead) 5/16th BSF bolt that passes through the mag's flange and the timing cover from the tricky side, with a nut (dab of loctite or a new nylock - don't want it undoing in there) and washer recessed into the chest behind the pinion on the oily side. Once the pinion's pulled, that nut undoes easy as falling off the proverbial with a box spanner or a turned down socket, the other 2 nuts come off their studs in a twinkle and the mag is in your hand in no time. Didn't the more grown-up twins have the same, or am I the beneficiary of a prior owner's sound common sense? Whichever, I rejoice. And Biscuit's point about the rear dual seat mounts is more than well-made - what a pain they can be. Groily

Steve Dempster · Post by **Steve Dempster** » Fri Jan 04, 2008 11:28 pm

Good points from each here. I've had the extra-long nuts (no sniggering please) suggested to me but (as well as can be seen) I'm not sure that the lower one on the mag would clear the gearbox plates. I like the idea of the Nyloc inside the timing cover to hold the bottom mounting (seems a darned good idea to me) and in fact I got mine out by jamming the existing nut and turning the bolt-head with a ground-down socket. As a piece of design it is truly terrible, along with those totally stupid rear dual seat bolts - a true stroke of daftness!

Biscuit - I'm terribly sorry old horse but I do not understand Klingon in any of its variants. "Chuck a piece of .6" AF hex.," - chuck it where? over the wall and probably through next door's greenhouse if I had anything to do with it, I can tell you - the only metalwork I understand is straight razors...(honestly)Edited by - Steve Dempster on 04 Jan 2008 11:30:02 PM

Biscuit · Post by **Biscuit** » Sat Jan 05, 2008 10:19 am

I'd have trouble explaining that with out sounding patronising. If you know somebody with a lathe, they will know what is required.

I think it is the best solution, well I would wouldn't I?

Steve Dempster · Post by **Steve Dempster** » Sat Jan 05, 2008 11:30 am

Sorry Biscuit - I did understand a bit but you've gone way beyond my skimpy knowledge! Now to track down a lathe-owner...

On the subject of awkwardly-placed nuts, I notice a little gizmo in Classic Bike Guide called 'finger spanners' - small nut-holders that slip onto the finger and, er, hold a nut. Anyone used them and if so are they any good? Might be an answer to the seat-mounts at least!

BTW - on my bike there is a panel (that I believe was listed as an 'optional extra'?) between the oil tank and battery box. It has a circular hole in it and looks like it should contain a filter box or some such. Problem is that the main downtube seems to run far too close to it to fit anything much in there. Can anyone elucidate (stands well back from the avalanche...)?Edited by - Steve Dempster on 05 Jan 2008 11:33:02 AMEdited by - Steve Dempster on 05 Jan 2008 11:33:58 AM

Don Madden · Post by **Don Madden** » Sat Jan 05, 2008 4:49 pm

What year & model? Some twin frames, up the 1955, have a hole for the air cleaner hose.
Cheers, Don.

Steve Dempster · Post by **Steve Dempster** » Sat Jan 05, 2008 4:56 pm

Hi Don - it's a '62 G12. It just seems that, although the hole is obviously for some sort of hose - it's directly in line with the carb mouth - there seems very little room for a filter box due to the downtube. Odd.

itma · Post by **itma** » Sat Jan 05, 2008 5:14 pm

I think the connecting hose carb to filter was offset to clear that frame tube; possibly some of these panels had an offset hole too.

The air filter fittted at the back of the tool box, not directly behind that panel

So few AMC bikes were fitted with air filters as new they are a rare item, and from what I remember they were quite a slim and odd shape. Probably none too efficient.Edited by - itma on 05 Jan 2008 5:16:29 PM