G2CS gearbox, trouble with 1st gear

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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G2CS gearbox, trouble with 1st gear

Postby Redbeardindustries » Sun Jul 21, 2019 10:03 pm

Hi all,

I recently bought a 62 G2CS and have been doing my best to get it running and riding again after sitting for many years. So far I've got the engine, electrics and clutch pretty well sorted out but the trans is being a pain.

I'll just list the symptoms
1. When engaging 1st, the kicker arm will also rotate down and cause 1st to disengage.
2. If I'm rolling in 2nd gear and downshift to first I can use first gear till I give it the beans then itll pop out of gear.
3. Sometimes when I kick the bike over the kicker will go through the motions but feels like I've pulled in the clutch slightly, so instead of rolling the engine over it's just clutch slip?
4. I added the .020 spacer per the manuals suggestion of first gear skipping, and for the first ride around the block first did work well.

Any help is greatly appreciated.

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Re: G2CS gearbox, trouble with 1st gear

Postby clanger9 » Mon Jul 22, 2019 5:44 pm

This can be caused by too much end float on the layshaft. The layshaft bushes may well be worn out.
I made a guide to overhauling the LW gearbox here: https://www.ifixit.com/Guide/AJS-Matchl ... 77#s171887
1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Re: G2CS gearbox, trouble with 1st gear

Postby Redbeardindustries » Mon Jul 22, 2019 9:06 pm

Thank you clanger9, I'll pull it back apart and have a look at the bushings. It wouldn't surprise me one bit if they were worn. It certainly looks like this bike has lead an adventurous life.

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Re: G2CS gearbox, trouble with 1st gear

Postby clanger9 » Tue Jul 23, 2019 5:11 pm

PS: looks like an excellent project. Good luck!
Genuine CS bikes are rare - hopefully it's got the proper gearbox & high compression engine. A proper little flyer! :-)
1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Re: G2CS gearbox, trouble with 1st gear

Postby Redbeardindustries » Tue Jul 23, 2019 9:43 pm

Thanks! It's my first dive into the matchless brand. I'd seen a handful at vintage shows over the years and they had always piqued my interest a bit but they rarely pop up for sale, at least around me. It's been a pain trying to find info on these bikes and I'm really happy to have stumbled upon jampot. How would I go about telling if it's a proper cs? The case number reads 62/G2CS9473 and there's a number on the frame 12179. This is all new territory for me, I've mainly been a harley, honda, triumph, bsa guy.

My overall goal with the old girl is to get her mechanically sound and preserve its "as found/raced" condition as best I can. Maybe do some vintage hare scrambles and bring it around to the vintage shows.

Thanks again for helping

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Re: G2CS gearbox, trouble with 1st gear

Postby clanger9 » Wed Jul 24, 2019 6:59 am

If you're new to these bikes then you definitely want to check out Christian's archives here: http://archives.jampot.dk
There's a wealth of information, including parts books & owner manuals for your bike.

I can't comment on whether your CS is a real one - there are others here who will weigh in!
Having a CS engine number is a good start... ;)
1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Re: G2CS gearbox, trouble with 1st gear

Postby clive » Wed Jul 24, 2019 8:39 am

Hi Ethan and welcome to the forum. You may be able to find more information through the clubs dating service at http://dating.ajs-matchless.com but having just tried it i am not sure you have the correct frame number. Has it also got a letter before it?
The club has recently bought up a large amount of lighweight spares but to access the spares scheme you will need to be a paid up member. Joining the club will give you full access to the website and and up to the minute access to the adverts. As a website guest you will only have limited access for 3 months. good luck with your project.
clive
if it ain't broke don't fix

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Re: G2CS gearbox, trouble with 1st gear

Postby garyg2mad » Wed Jul 24, 2019 1:24 pm

Hi Ethan ' you have what appears to be a genuine late model G2 Arrow CS ' The frame number number sequence is about right for 61/62 'The competition Swinging arm ' rear subframe ' And footrest mounting tray with silencer mount hole ' all correct ' The engine is definitely a CS with offset crankcase centre line ' US models had the highest compression 10.5 -1 with a valve lifter ' Which yours has ' Be carefull with the plug reach on this piston ' Gearbox number should be around GS 9--- ? If the correct one with higher first gear ' It looks like the battery mount on the fear of the frame has been removed ' This is the same as a std one ' But welded on about 1/2 inc higher for the 19' rear wheel' The rear brake plate on the US ones have two captive nuts in for mounting the sprocket guard ' Yours has this ' Looks like it's had some competition time in its past
Good luck with it
Hope this info helps

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Re: G2CS gearbox, trouble with 1st gear

Postby Redbeardindustries » Wed Jul 24, 2019 8:54 pm

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I really appreciate all the info and welcomes. I just signed myself up for a years membership, as far as I'm concerned I've already gotten my money's worth from this post alone.
The frame does not have a letter designation that I can see, I'll have to have a closer look to find the trans numbers.
Are there some good cross reference bikes for clutch parts? I ended up making clutch studs and spring nuts for this bike, unfortunately one of the original studs was unsalvageable. The studs that were in it were 3" overall length and the pn in the book lists studs as being 2.5". I'll have a look at the spares page for other bits I need like the innermost and outer one sided fibers.
All this info and resource material has got me pretty excited.

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I'll be sure to keep you all updated on the bikes progress.

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Re: G2CS gearbox, trouble with 1st gear

Postby clive » Wed Jul 24, 2019 11:04 pm

Hi Ethan. Two issues. Firstly you are not logged in as a member so you do not have full access to the site. To get this sorted out you may need to email Eamonn at webmaster@jampot.com . Secondly having tried the dating service again it has indicated that they have factory records for your frame number if you choose "all categories" rather than "lightweight" as i did last time. Welcome to the club.

Edit you are now appearing as a member
clive
if it ain't broke don't fix

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