Engine rebuild thread

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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Re: Engine rebuild thread

Postby clanger9 » Sat Feb 03, 2018 4:16 pm

Engine in frame, inner primary case fitted. Nice & tight with new screws, thread lock and gently staked into place.
image1.jpeg

...and guess what I forgot? The gearbox retaining straps and retaining bolt must be fitted first. :headbang:
image2.jpeg

I don't want to take the primary case off again if I can help it, so I'm going to try and fit the retaining nut via the little access hole in the crankcase. I think it'll be just about possible. This is going be a test of patience...
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1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Re: Engine rebuild thread

Postby clanger9 » Sun Feb 04, 2018 6:24 pm

Good news: it is possible to fit the retaining strap bolt without taking the primary case off. Fiddly, but possible.
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Re: Engine rebuild thread

Postby Ozmadman » Sun Feb 04, 2018 6:26 pm

clanger9 wrote:I span the engine over today using a battery drill and everything seems OK. Oil feed to the cylinder head looks healthy:

Green oil? Looks like Duckhams 20w/50 from years past
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed

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Re: Engine rebuild thread

Postby clanger9 » Sun Feb 04, 2018 6:58 pm

Halfords Classic 20w/50. The factory manual says SAE 50, but the F Neill manual says SAE 20/50 is also fine...
1966 AJS Model 14 250 CSR "cafe racer"
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Re: Engine rebuild thread

Postby clanger9 » Tue Feb 06, 2018 3:13 pm

Regarding piston rings: I got a little confused because the 1965- owners' manual says that the top ring is chromed and tapered. However, I couldn't find any "TOP" indication on the replacement rings. Martin from Cox & Turner has confirmed that their replacement rings are plain and can be fitted either way up.
1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Re: Engine rebuild thread

Postby clanger9 » Mon Feb 12, 2018 8:49 pm

Success on the collet front (I think): after being delivered to the wrong address, the collets sent by Steve eventually turned up. Yay! Unfortunately, they don't fit my bike. Boo!

Steve's collets were the right internal diameter (to fit the inlet valve's unusual 9/32" stem), but were too fat for the spring retainer. Maybe my spring retainers are incorrect? Fortunately, I have one inlet collet that does fit, so I took a chance and hand-fettled an oversize collet down to something like the right size.
IMG_2336.jpg

OK, maybe not the perfect solution, but certainly better than the POs arrangement (where the valve stem was barely gripped at all). Let's hope it holds together...
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Re: Engine rebuild thread

Postby shifter » Tue Feb 13, 2018 5:53 am

Hope it works good luck
?

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Re: Engine rebuild thread

Postby clanger9 » Sat Feb 17, 2018 8:35 pm

Now this feels like progress. Valve-to-piston clearance all fine, engine timed and cylinder head on. All torqued up nicely and it feels like it has loads of compression. Previously the engine had a plain copper gasket, but I've gone with the composite type because I usually find they work better.
IMG_2375.jpg

IMG_2376.jpg
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1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Re: Engine rebuild thread

Postby clanger9 » Sat Mar 03, 2018 3:14 pm

It's done! Thank you to everyone for the help and assistance. :beer:
https://youtu.be/Z-tk6qTqJy0
https://youtu.be/8IcylR9knCA

Engine seems happy enough, if a little smoky. Hopefully it'll clear up once I take it out for a run...
1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Re: Engine rebuild thread

Postby Rangy65 » Sat Mar 03, 2018 3:44 pm

That great news!! checked out your U tube sounds great - Well done!!

Steve

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