54 AJS 500 petrol?

**BADGRL** · 10th February 2012, 21:23

Hey guys,

I'm curious as to what octane I should be running the ol' girl on?

Also does anyone have any thoughts on the following.... http://www.trademe.co.nz/motors/moto...-447626675.htm

**pete376403** · 10th February 2012, 22:19

I'd guess it is fairly low compression so the regular swill should be ok, but you might look at a fuel additive unless the motor has had the valve seats replaced with ones suitable for lead free petrol.

edit: looked at the TradeMe ad - no experience with that at all, sorry

**DrunkenMistake** · 10th February 2012, 22:21

I should think if they needed a catalyst for 95 then I would go with 91, but I have a sneaky feeling they need mixed fuel with some oil?
Try source the likes of a maintenance guide im sure there is a forum somewhere for them

**Ixion** · 10th February 2012, 23:14

Compression ratio, if it's still standard , is 5.9:1 !

Pump petrol in the early 50's was 68 octane. Dunno where you get 68 octane now.

You,ll need to put in one of those tubes of lead replacement now and then. No idea about the gadget you link to, though tin would be a suitable lubricant. That's assuming it's an alloy head. Some early AMC purporting to be early 50's models were actually ex Army iron head models, sold off after the War.

**pete376403** · 11th February 2012, 21:43

Are we talking about the single or twin cylinder? Is this the one you were looking at selling a while back?

**BADGRL** · 11th February 2012, 22:57

It's the twin. Haha yeah I couldn't part with it! Just had everything fixed up now she's ready to roll

Lmao @ 68 octane.... could be tricky to find.

**BADGRL** · 15th February 2012, 17:33

Soooo 91 octane with additive is pinking rather badly.... perhaps 95 without? then maybe look at the timing :S

**Flip** · 15th February 2012, 20:21

Well white spirits is 50 octane unleadded petrol.

I used to do a blend with 50-50% pump gas-white spirits and a splash of Avgas for the lead and run it in a racing Austin 7. I never found it ran any better or worse than straight 91 pump gas. Valve master seems to work OK preventing the valves welding themselves into the head (VSR). I do not see how oil can prevent VSR as no hydrocarbon will sit around at exhaust valve temperature.

Sounds like the timing is out.

**craisin** · 19th February 2012, 21:15

A lot of bikes of that age had advance retard lever un the handlebars

**Paul in NZ** · 20th February 2012, 07:21

First thing I'd do is join the AJS / Matchless owners club.

http://www.jampot.co.nz/

and if you look here

http://www.jampot.co.nz/pages/help.html

They have technical specialists for the different models. The one you want is even in ChCh so how can you go wrong???

By way of a warning - this is an old bike. Wonderful things but they do require you to get 'involved' and no two are identical so what has worked for one might not work for them all. However, in general I'd be very surprised to see valve seat recession in it due to unleaded fuel and I'd be equally surprised if it didn't run very rich on the std settings for the old unleaded. You may need to go to a hotter plug but if it still has an AMAL Monoblock you can adjust the pilot jet.

Having said that - Chuck some 98 in it and see how she goes and ring the specialist ;-)

**BADGRL** · 24th February 2012, 16:30

Great thank you all for the info! I have just sent membership away to the jampot club

Ran into an older gentleman at St n Sport last week - previous owner of 3 ajs/matchless bikes and he answered all my 100 questions and more rofl.

Hehe I have discovered the retard lever along with straight 95 gas and she's running like a dream! ... Now to fix the oil pumps