AJS & Matchless Owners Club

Hello. You will have seen that recently I have placed a couple of posts about the G9 "Bitsa" I acquired recently. It is fitted with the frame front end from a G80s. I may have the possibility of picking up a G9 frame front end to replace the one that's fitted. So far so good. However, before I do this I want to check what the pedigree is of the fuel tank that is already fitted. I have read on an old post on this forum that the fuel tanks for twins and singles are different. (Larger/smaller capacity). If that is the case if I buy the G9 frame am I going to find that the tank (if it's off a single) wiil not fit? So can anyone please send me the dimensions of a G9 tank. As well as the width and length of the tank it would be useful to have the distances between the mounting holes.

Many thanks to those who have helped me already and to those will no doubt in the future. Paul.

Paul I believe the difference is more in the cutaways underneath to clear the head and rocker box/valve lifter of a single, the location of the petrol tank mounting points are the same, if you have a twin downtube frame the tank of a single downtube frame will not clear the twin tubes.
You will need to provider details of the years of the frames and pictures of the underside of the tank for definitive answers but as a rule of thumb anything 1950's should be okay for a 1950's 500cc twin.

Paul I mentioned this in one of your earlier posts but I wonder if you realise the implications of changing a frame. Firstly of course you have to remove and replace engine, gearbox, front forks and rear frame loop and swinging arm. You will probably need to rewire it too but you may be able to slide the wiring across.
You then have two options. Firstly pretend you have not done it and continue to use the bike on current number. Unlikely anyone will check the frame number but not entirely legit. Until of course you come to sell the bike when the V5 will not match.
Alternatively you tell DVLA and they will consider it to be a different bike as the registration number is linked to the frame number. This will entail registering the bike and claiming an age related number as outlined in the dating section. https://www.jampot.com/Dating.asp
The bike will probably be inspected by an independent assessor and you cannot make an application until its fully rebuilt and has an MOT based on the new frame number. You will be issued with a non transferable registration number.

I am sorry your purchase has not turned out to be what you thought but changing the frame is going to be quite a big task. Good luck if that is the route you follow and I hope it works for you.

Thank you Duncan and Clive. My plan is to get the bike running and then assess quite what is required. I suspect it will be a great deal more than I would hope. I'll then decide how far I want to go with it. I must admit that after my initial disappointment the thought of keeping the frame that it has is becoming more agreeable. However, job one as I say is to get the machine running. Thanks again for your advice. Paul

Clive's right. I always think you can't see the frame isn't right when you're riding along enjoying yourself in the sun!
Dave.

The fact that the frame isn't right will not make the bike ride any worse or better!
Nobody but a rivet counter will ever know and their opinions count for very little anyway!
The fact is you will have got another old bike on the road and stopped it gathering dust at the back of some old shed . It will not diminish your enjoyment of the machine.

Singles tank have larger cutout beneath. A single tank fits also a twin, a twin tank doesn't have to fit a single. For capacities there were a few different ones, but that's a longer store, with less practical significance.

Paul I think the general advice is relax and enjoy the bike. I have both Bitsas and number matching bikes i get similar enjoyment from them regardless of which type.

What a nice bunch of guys! Thank you for your comments and advice. I'm certainly feeling more relaxed about the whole project with my focus moving more to getting the machine back on the road. Paul.