1959 650 rebuld help

Information relating to the Matchless G12 or AJS Model 31 650cc twin
Groily
Member
Posts: 2151
Joined: Thu Jul 04, 2002 1:00 am
Location: NORMANDIE FRANCE

Re: 1959 650 rebuld help

Post by Groily »

I don't know my way round them like many others do, but this is probably where you need to be for info: http://archives.jampot.dk/Book/Spares_lists/ - Tons of stuff, but a bit of a fiddle to navigate some of it. See page 24 of this pdf for twin crank grinding instructions: http://archives.jampot.dk/book/Workshop ... CHABLE.pdf
(Matchless or AJS - all the same, just the badge.)

If your radii are off spec, then there is no good repair as the points of weakness are 'embedded' and not recoverable. A lot of machine shops will not be aware of the ins and outs of this stuff and I don't know who are the go-to folk in NZ. The only crank I ever had break had been built-up to standard on dodgy radii - and the result was a spiral fracture next to a web. It follows as night follows day if there is a defect! But apart from that I've had these engines in continuous use for over 40 years without any other major breakage.

Club members down there must be the place to start I'd have thought. The cranks can successfully be built up - if the radii remain good, the rods made good if they don't have any cracks, and barrels can be resleeved etc. I always send these sorts of problems to T&L Engineering near Bedford in the UK myself (see ads in Jampot magazine), because they are very good (and hang the postage from where I am, it's worth getting it right). Others use other specialists with similar skill sets.
McBob
Member
Posts: 151
Joined: Sun Sep 19, 2010 10:17 am
Location: AUCKLAND NEW ZEALAND

Re: 1959 650 rebuld help

Post by McBob »

Someone will know who to use http://www.jampot.co.nz/, unfortunately the bloke who rebuilt my knackered engine is
no longer with us.
SOHC
Posts: 36
Joined: Tue Mar 07, 2017 11:04 pm
Location: Newzealand

Re: 1959 650 rebuld help

Post by SOHC »

Groily wrote:I don't know my way round them like many others do, but this is probably where you need to be for info: http://archives.jampot.dk/Book/Spares_lists/ - Tons of stuff, but a bit of a fiddle to navigate some of it. See page 24 of this pdf for twin crank grinding instructions: http://archives.jampot.dk/book/Workshop ... CHABLE.pdf
(Matchless or AJS - all the same, just the badge.)

If your radii are off spec, then there is no good repair as the points of weakness are 'embedded' and not recoverable. A lot of machine shops will not be aware of the ins and outs of this stuff and I don't know who are the go-to folk in NZ. The only crank I ever had break had been built-up to standard on dodgy radii - and the result was a spiral fracture next to a web. It follows as night follows day if there is a defect! But apart from that I've had these engines in continuous use for over 40 years without any other major breakage.

Club members down there must be the place to start I'd have thought. The cranks can successfully be built up - if the radii remain good, the rods made good if they don't have any cracks, and barrels can be resleeved etc. I always send these sorts of problems to T&L Engineering near Bedford in the UK myself (see ads in Jampot magazine), because they are very good (and hang the postage from where I am, it's worth getting it right). Others use other specialists with similar skill sets.

Thank you for that link, I am going to get that printed, I took the crank and rods to a place and I will give them that info and he sed he might be able to get the radius ok,
SOHC
Posts: 36
Joined: Tue Mar 07, 2017 11:04 pm
Location: Newzealand

Re: 1959 650 rebuld help

Post by SOHC »

McBob wrote:Someone will know who to use http://www.jampot.co.nz/, unfortunately the bloke who rebuilt my knackered engine is
no longer with us.

I will try contact a few people from there, I have found a lot of the old knowledgeable guys have passed lately, Bob Nesbit was a friend of mine and helped me alot over the years but is gone now.
JEAN-NOEL
Member
Posts: 601
Joined: Wed Oct 12, 2005 10:45 pm
Location: FRANCE

Re: 1959 650 rebuld help

Post by JEAN-NOEL »

I agree with Groily. T & L were helpfull for me. I had ordered a new crankshaft, but after being waiting it for 3 years, I was in Elstow to T & L with my G12 CSR engine, and having seen my crankshaft, Derrick said me : be confident, your crankshaft is O.K. Very good service.
SOHC
Posts: 36
Joined: Tue Mar 07, 2017 11:04 pm
Location: Newzealand

Re: 1959 650 rebuld help

Post by SOHC »

is there a bigger size piston than +60?
JEAN-NOEL
Member
Posts: 601
Joined: Wed Oct 12, 2005 10:45 pm
Location: FRANCE

Re: 1959 650 rebuld help

Post by JEAN-NOEL »

No, you have to find new barrels from .20 to . 40, or resleve yours to the standard bore.
Cheers.
TrevorCSR
Member
Posts: 80
Joined: Wed Oct 07, 2015 9:12 pm
Location: HERTFORDSHIRE UK

Re: 1959 650 rebuld help

Post by TrevorCSR »

With 1 thou wear, I'd leave it as it is. Have you checked the ring gap?
SOHC
Posts: 36
Joined: Tue Mar 07, 2017 11:04 pm
Location: Newzealand

Re: 1959 650 rebuld help

Post by SOHC »

I think resleveing would be the better option, I think it would be nealy impossible to find a good pair of barrels, my frind spent over $25,000 NZD making pattons and casting Norton Domonator 500cc barrels.


I checked the ring gap only in the top of the bore and it was 014", I haven't had a chance to give the cylinders a proper measure but I think someone has all ready deliped the bore and they are tapered.

Its a shame as those +60 pistons and rings have had about 10 mins running
SOHC
Posts: 36
Joined: Tue Mar 07, 2017 11:04 pm
Location: Newzealand

Re: 1959 650 rebuld help

Post by SOHC »

I took the barrels to an old British bike mechanic and he started laughing as he saw what I had in my hands but he sed they are ok to use and don't get carried away with a resleave just yet.
Locked