Help identifying g15cs

Ian millard · Dec 24, 2019

hello everyone just joined the forum
I have recently bought a matchless in bits
The frame number is a75554
Chassis number starts g15cs109080m2
It’s suppose to be a pre production scramble version
It has the small tank upswept pipes knobbly tyres
It’s always been in the uk
Can anyone shed any light on this for me
Thanks for any help
Ian

mdt-son · Dec 24, 2019

Ian,

It seems you have a 1961 G12 frame and a 1963/4 G15Mk2 engine. If the frame number is genuine, I doubt the frame is a pre-production version. Why would the factory use a 2 year old frame, which has the wrong headstock? Beyond all, the G15 engine doesn't line up with a G12 frame.

Of course it's possible someone re-stamped a G15 frame for obscure reasons. This was certainly not done by the factory.
Have you tried to mate the engine and frame using the proper engine plates?
A75554 G12 would be stamped at the right downtube below the headstock. A G15 frame would be stamped at the left downtube below the headstock.

-Knut

pierodn · Dec 30, 2019

mdt-son said:
Ian,

It seems you have a 1961 G12 frame and a 1963/4 G15Mk2 engine. If the frame number is genuine, I doubt the frame is a pre-production version. Why would the factory use a 2 year old frame, which has the wrong headstock? Beyond all, the G15 engine doesn't line up with a G12 frame.

Of course it's possible someone re-stamped a G15 frame for obscure reasons. This was certainly not done by the factory.
Have you tried to mate the engine and frame using the proper engine plates?
A75554 G12 would be stamped at the right downtube below the headstock. A G15 frame would be stamped at the left downtube below the headstock.

-Knut

Hi Knut.
As i can see from my bikes, there are not main differences between G12 (the later type already with roadholder forks and Norton wheels) and G15 frames.
Could 75554 not be a G12 frame?
I have a part a 86783 frame (ii dont know from were it comes) that could seem the same of G15 (has a later swinging arm for Norton wheel) but has the main difference to have the right bottom lug larger than G15 so that you canot line up the engine plates without cutting first this lug.
Piero

pierodn · Dec 30, 2019

Ian millard said:
hello everyone just joined the forum
I have recently bought a matchless in bits
The frame number is a75554
Chassis number starts g15cs109080m2
It’s suppose to be a pre production scramble version
It has the small tank upswept pipes knobbly tyres
It’s always been in the uk
Can anyone shed any light on this for me
Thanks for any help
Ian

Hi.
My G15 has frame 10983. and engine G15CS/10983. M2 that means it is a 1964 MK2.
This type had large thank with great alu badges, both large ribbed fenders, large dual seat, and lower pipes.
Has your swinging arm the rounded join to accomodate the Norton rear wheel or is it stright like early type?
Swept back pipes were fitted on G15 CSR type, not CS.
Ask to Knut, he knows every thing, he is an autority.
Piero

mdt-son · Dec 30, 2019

pierodn said:
Hi Knut.
As i can see from my bikes, there are not main differences between G12 (the later type already with roadholder forks and Norton wheels) and G15 frames.
Could 75554 not be a G12 frame?

The G15 frame is indeed a development of the 1964 G12 frame (and the G3/G80, for that matter). If A75554 is a legitimate stamping, it can´t be a 1964-on frame.

pierodn said:
I have a part a 86783 frame (ii dont know from were it comes) that could seem the same of G15 (has a later swinging arm for Norton wheel) but has the main difference to have the left bottom lug larger than G15 so that you canot line up the engine plates without cutting first this lug.

Your frame with serial no. A86783 is probably a late model G12 frame. While I have never compared the last model G12 and G15 frames one to one, two or four front lugs will be positioned differently and stud bolt sizes may differ as well.

Edit: Going by the pictures received, the frame number as without the prefix 'A' and the number is stamped in the wrong place. Indeed, frame no. 86783 belongs to a late 1952 model.
http://archives.jampot.dk/general/Matchless_Frame_Numbers_1950-1966_AJSMOC.pdf
Now, that can't be since technically the frame corresponds to a 1964-66 duplex frame, with provision for Roadholder forks and a swinging arm to take a Norton rear wheel. Therefore, I suspect the bike was stolen and the frame re-stamped to make it "road legal".
It would be interesting trying to recover the genuine frame number!

-Knut

mdt-son · Dec 30, 2019

Ian millard said:
hello everyone just joined the forum
I have recently bought a matchless in bits
The frame number is a75554
Chassis number starts g15cs109080m2
It’s suppose to be a pre production scramble version
It has the small tank upswept pipes knobbly tyres
It’s always been in the uk
Can anyone shed any light on this for me
Thanks for any help
Ian

Hi Ian,

What´s the difference between a frame and a chassis, in your book? I took "chassis number" to be engine number stamping.

-Knut

pierodn · Dec 30, 2019

mdt-son said:
The G15 frame is indeed a development of the 1964 G12 frame (and the G3/G80, for that matter). If A75554 is a legitimate stamping, it can´t be a 1964-on frame.

Your frame with serial no. A86783 is probably a late model G12 frame. While I have never compared the last model G12 and G15 frames one to one, two or four front lugs will be positioned differently and stud bolt sizes may differ as well.
Matchless g11

Hi Knut.
I think that 86783 could be a 1965 G3 or G80.
The larger right bottom frame stud lug is not compatible with a twin engine.
Piero

mdt-son · Dec 30, 2019

pierodn said:
Hi Knut.
I think that 86783 could be a 1965 G3 or G80.
The larger right bottom frame stud lug is not compatible with a twin engine.

Possibly. The frame was manufactured in the june-august 1964 time span, prior to the 1965 models.
Matchless roadster frame numbers were used for both AJS & Matchless, as well as type of machine (single / twin engine).
Meaning your frame could be for a single and the lugs differed from those used on the twins, AFAIK.
It´s necessary to look up the dispatch records to verify which type of machine the frame was made for.

Edit: See #5 for new information pertaining this frame.

-Knut

pierodn · Dec 30, 2019

mdt-son said:
Possibly. The frame was manufactured in the june-august 1964 time span, prior to the 1965 models.
Matchless roadster frame numbers were used for both AJS & Matchless, as well as type of machine (single / twin engine).
Meaning your frame could be for a single and the lugs differed from those used on the twins, AFAIK.
It´s necessary to look up the dispatch records to verify which type of machine the frame was made for.

-Knut

Yes

pierodn · Dec 31, 2019

AJS & Matchless Owners Club: Machine Dating Request says that 86783 is a 1952 G3L.

kommando · Jan 2, 2020

In UK DVLA language the frame number is the chassis number and the engine number is the engine number.

Ratboiler · Apr 19, 2020

Hi
Not sure this is any help but I have a G15 Mk2 1964 sitting in my garage.
I bought it without the original engine the frame number is 110804, I obtained an engine no G15CS 108984 which I believe is from a later bike.
It's been sitting in my heated garage now for 35 years ......I must get round to sorting it soon.
It has the original tank with badges, original deep valanced mudguards, new exhausts and new old stock silencers.

mdt-son · Apr 19, 2020

Hi Ratboller,

You are lucky to have a chassis with all or most of the sheet metal there. Especially the mudguards are very rare. Some repops were commisioned in India by"Ironjohn". We have not managed to track him down lately - he is possibly diseased.
I hope you get on with your restoration, and please post some pictures and a few words on how work is progressing.

- Knut

Ratboiler · Apr 20, 2020

Hi Knut
Thanks for the mail, I plan together to it and sort it out asap after the Commando.
I had a few problems while putting it together, like rear wheel locking up when tightened, tyre I bought for the rear is too wide, center stand fouling a gearbox
nut so couldn't get the primary drive on.
Bought a set of new exhausts which were for one of the other G15s didn't fit mine, engine and gearbox are all done. Gave up in the end but never got round to selling it.
I see you are in Norway my son lives in Oslo.

mdt-son · Apr 21, 2020

Hello ratboiler,
I grew up outside of Oslo but have been living in western Norway for almost 30 years. We are driven by available workplaces, right?

Did you solve the problems you had with the bike in the past? Can't help with the rear wheel - a quick search on this site will most likely render answers.
Rear tires for the G15Mk2 is 4"x18" for sidecar work (WM3x18 rim) and 3.50x18 for solo operation (WM2x18 rim). The latter is a strange choice - Dunlop recommends rim width WM3. As for the center stand fouling a g/b nut, direction of bolt matters. This is a well known issue.
For this heavy bike, upgrading the center strand to the one developed by Rob of the Owner*s Club might be a worthwile.
Yes, obtaining exhaust pipes with the correct bends is a recurring matter for several makes and models. Keep the genuine pipes, at least as templates. Old pipes do not wear out quickly, and dents can be dealth with, chrome likewise. The cigar-shaped mufflers are available, talk to Mike at Walridge Motors.

-Knut

Ratboiler · Apr 22, 2020

Hi Knut
Yep retired now, worked in Stavanger and Oslo for around 6 years got married/divorced you know the story.
No I did not sort the problems from the past they just became a pain and I gave up.
I have most of the parts to get it going including 3 original Burgess new silencers, and two fuel tanks painted and ready to go. Just need the enthusiasm to do it. At the time I did not have a hydraulic table which I do now. So finish the Commando, then the G15.
Many year ago I bought a pair of monobloc carbs from Mike one standard the other chopped.
Take care
Regards
John

Arizona · May 15, 2020

I'm a new member and this post is a little late on G15 frames but outside of the head stock bearing area a little taller and the angular lug for the steering lock, the upper front mounting lugs on the down tubes are moved up about 1/2 inch and the right one is flipped 180 so it is offset to the outside instead of to the inside for the Norton engine. The mounting points for the Matchless singles and twins are the same. Any Matchless swing arm will pin onto the frame early late or Norton style.

Help identifying g15cs

Similar threads