1961 ALS 350 ?Mongerel

[Bill2181]

I've just bought a 1961 350cc, but on stripping down the engine, it has a 69mm bore, but the stroke is only81mm, not the 93mm it should be. there is also an approx. 10 mm unswept area at the top of the cylinder.
So from the figures given it's a 1962 (short stroke) bottom half mated with a 1961 cylinder and piston.
Has anyone got any thoughts? Could it have been assembled that way at the factory during the change over period between models?
The engine No is 61/16/41164 if that helps.
Alternatives are 1) fix the engine to 1961 or 1962 with second hand spares,
or )2....edited by Adverts Editor.
Thanks in anticipation of a happy outcome
Bill2181

[clive]

Hi Bill, we don't allow adverts in the open forum. You are welcome to place a wanted ad, free to paid up club members, £5 for forum guests, it will reach a much wider audience as it goes in the club magazine. Fraid I cannot help with advice on short strokes.
regards Clive Adverts Editor

[bodgert]

Probably just been fitted with short stroke flywheels Short stroke crankcases will not marry up with long stroke barrel and head

[alanengineer]

60 years of bodging. hope you find the answer. Lots of free info available for Matchless and AJS on the net and a good restoration book by Roy Bacon

[Bill2181]

Hi all, It was rude of me not to introduce myself in my first message.
I am relatively new to motorbikes, not having owned one since I was 17,and that's a very long time ago.
I have restored a few cars since retirement, but crawling underneath them has become more difficult with the advancing years.
So I decided to try a motorbike instead and the 61 AJS (mongrel) came along.
It is plainly a mix of 1962 (Short stroke) and 1961 (barrel and piston)
The unswept 10mm at the top of the bore means approx 40cmm extra combustion chamber volume which will yield a low performance engine.
I wanted to ask about the spares situation, being used to the fantastic service of the many Morris Minor and MG spares firms I've used previously, but it was unfortunately taken as advertising.
Many thanks for the replies received. I will continue and hope to get the better of Mongrel.

[clive]

The club has a spares scheme, currently working on-line only but you have to be a member to purchase from it. There are other suppliers some of whom advertise in the club magazine. A quick internet search will throw up the two key competitors AMC classics and Russel motors.

[ajscomboman]

Depending on what you require, I have barrels and pistons and rods in my shed, and only in Southampton. When this situation has finally calmed down you could pop over and have a look. I may even be able to sell a very nice roll on/off stand at the same time!


Sorry Clive, had to be done as you deprived me the opportunity the other day!

[Reynard24]

Hello Bill
If the stroke of your crank is 81mm it is indeed a 1962/3 ultra short-stroke and as Bodgert says the barrel will not fit on long-stroke cases as all the short-strokes use through studs and sleeve nuts to secure the head and barrel, the short-stroke barrels have the pushrod tunnels cast in and the head is also different. The ultra-short stroke 350s are in fact akin to a pushrod 7R and certainly are not a "low performance" engine. They thrive on revs and crack along very nicely.
To paraphrase the original AMC Owners Club poster - you cannot do better than to join the club to gain access to the forum and its many knowledgeable contributors and to search for long stroke 350 spares from the various suppliers already mentioned.
Once we're out of this C-word mess your local section would also be able to provide a huge amount of information too.
Regards
James

[Bill2181]

Depending on what you require, I have barrels and pistons and rods in my shed, and only in Southampton. When this situation has finally calmed down you could pop over and have a look. I may even be able to sell a very nice roll on/off stand at the same time!


Sorry Clive, had to be done as you deprived me the opportunity the other day!

Hi ajscomboman, many thanks for your reply. Once this corona business is over I would hope that your stock of bits and bobs may solve my problem. From the other replies it would appear that the earlier (93mm stroke) flywheel and conrod will be required.
For the benefit of Clive, I shall place an ad in Jampot.
From my Roy Bacon book it appears that the 93mm stroke was used all the way back to 1945. Can anyone confirm that?
Bill

[SPRIDDLER]

From my Roy Bacon book it appears that the 93mm stroke was used all the way back to 1945. Can anyone confirm that?
Bill

According to the factory Owners Manual it was 93 in '41:

http://archives.jampot.dk/book/Owners_m ... Manual.pdf

And as far back as 1939:
archives.jampot.dk/book/Owners_manuals/1939_AJS_Instruction_manual.pdf

1939 350 bore stroke (532x421).jpg