AJS & Matchless Owners Club

That's so frustrating, seems like you have pretty much covered all the bases on sparking and fuel, is it time to look again at air and compression?
If I missed reference to recent compression test then I apologise but if not, then easy check bearing in mind original problem. Check it cold and hot..any difference? Wet test when cold? Is there an air slide in the carb, and is it fully open when you set off.. are you sure? Haven't left a packing rag in the carb throat, or fitted a filter?
Quick checks to remove doubt.

Thanks Andy

That's given me a few more things to check. The compression is a worry since the original valve seat problem - I can stand on the kick starter without it moving and I have to give it some wallop to turn it over but I'll look into measuring it.

The carb set up might be another one worth revisiting - after Micks message above I started the bike, warmed it up and then get it 3/4 throttle for 8 -10 seconds and it revs sweet. The choke slide works mechanically fine, the slide is completely up when I start and run the bike. I have a woven stainless steel wire (cone type) air filter - I've not tried running the bike without this on - I have washed it out in petrol and carb cleaner. Are there any other settings within the carb that might cause the problem ?

steadyrider wrote: ↑Sun Oct 24, 2021 1:29 pm .......new bob weight springs,.......

I've never had an auto A/R mag but unless I'm mistaken I believe that there are two attachment positions for the springs so is it possible that you have used the wrong ones and it's not coming off 'Retard'?

steadyrider wrote: ↑Sun Oct 24, 2021 6:55 pm I have a woven stainless steel wire (cone type) air filter - I've not tried running the bike without this on

Is the filter restricting airflow such that you should be using a smaller main jet?
(Although at up to just over a half open throttle the carb is still principally operating on the pilot jet and slide cutaway).

Hi

If you an stand on the kick start of a 350 for any appreciable amount of time there's probably something wrong elsewhere, or you're very svelte.

I can stand on mine for about a second or two before it goes over TDC.

Regards Mick

Ha..ha..not sure about svelte but my other hobby is long distance running - there isn't alot on me - my old mans Velo kicked back and threw me over the handlebars !!

steadyrider wrote: ↑Sun Oct 24, 2021 7:53 pm Ha..ha..not sure about svelte but my other hobby is long distance running -

Useful hobby when you've got an old bike.

Thanks Spriddler - I followed the manual on the springs but at this stage anything is worth a try

I haven't read all the ideas people have already said but is the bike in the "emergency" start position? Plus have you checked your condenser and reg/rec. Problems I had with my '61 Matchless.

Hi Jackstringer - no idea what the emergency start position is ?? I'll take a look in the manual.

I've changed the condensor, coil, HT lead, points, bob weights - I haven't checked any other components.

Sean

Just another idea Have you checked that the exhaust is clear If it's blocked at all the engine cannot breath properly
just a thought
Ian