AJS & Matchless Owners Club

I've just put the gearbox back in the bike, I was the layshaft bush saga, and rode around the neighbourhood a little. This is actually the first time I've ridden the bike since buying almost a year ago. I'm chuffed with my gearbox rebuild but now I have a question; do I have a hardened valve seat for unleaded?
I didn't get much history when purchased and the p.o. whom I can't contact at the moment only had it a short while. It has been extensively restored sometime and there is a bar code "phantom restorations" 2011under the seat. It's had extensive work because the piston is +40.
I had the head off 2019 and attached is a pic of the valves. I did take both valves out at the time and where in goo nick.Leading question; can I assume it'll take unleaded?

Sent from my SM-T580 using Tapatalk

Not had a problem in that regard. The only problem I had was when the exhaust valve guide came loose and had a valve seat replaced subsequently. That was due to letting someone who was supposed to know what they were doing and didn't do a job I could've (and had previously) done myself with no problem.

I'd ride it and not worry.

Johnny B

EDIT There are sometimes problems with valve seats turning but they are very unlikely to fall out because of the way they were installed, they're wider within the alloy than the part you can see.

The standard seats are fine with unleaded. Problems only occur if you exceed 4,000 rpm for long periods - unlikely on one of these bikes. Andy

Don't worry about it, these old bike engines are tough enough to withstand a bit of missing lead in the fuel. I would be more concerned about the up and coming E10 fuel and the corrosion issues than this. I have have my model 8 since 2011 and not had any problems

As stated above, these engines are fine on unleaded. The exhaust valve seat is a hardened insert.
For fuel, I'd recommend super unleaded. It's more expensive (and you don't need the extra octane), but super usually has much less ethanol in it...

Ok fellas that's reassured me.
Now to the next issue; last year when I bought this bike it didn't run. Head off and the gasket had been pinched on the spigot. Replaced gasket, blue smoke evident so moved on to gearbox refurb which is total success.
Now I've ridden only total of 5 mls and it's a struggle, symptoms are, starts well and accepts "choke" off so far so good. The engine tugs,snatches, hunts in all throttle or load configs. New idium spark plug quickly black and oily which wipes off with rag. There is no excessive smoke blue or otherwise following me.
The inlet valve needle is open the smallest amount, how good is it? I will torque check the head and the 5th head bolt which was nipped up is heli out to M8.
A pic earlier in this entry shows the head smeared with oil, this was last year after replacing gasket, running and having smoke, I suspect the same is happening again. How or why oil is getting into the cylinder is the Q. I think I'll end up taking head off again and then what?

Sent from my SM-T580 using Tapatalk

Copper or composite head gasket??? Is the timing correct??

Copper gasket. Timing, seems to start and run well. But if that could cause the problem I should check it. Sounds a bit elemetry but how do I check the timing. My strobe was binned at the airport security.

You might want to look at the auto advance and retard mechanism, they are nearly always worn out and replacements are not available, electronic ignition is the way to go.

That's a good point Dodger. I also had a dream last night that the plug fouling could be unburnt fuel not oil. Today I'll check timing, auto advance and maybe drop the needle a notch. Thanks chaps.