AJS & Matchless Owners Club

mikeydpippin wrote:checked timing again and it's spot on. starting to open 1/2” btdc.

On the compression stroke?
You said you used carb cleaner but did you remove the pilot jet to check that it isn't blocked?

Hi Nev,
Set timing with valves closed (ie able to spin pushrods) even replaced pilot jet with another cleaned one.
Just checked carb inlet rubber, all good and replaced gaskets inlet to carb..

Test a bit of petrol to see if it burns. If it's fresh and does, petrol should be OK. But if you have sumpped oil, the plug will oil up after 2/3 kicks fails to start the bike.

Will try that tomorrow Thanks Rob, possible fuel bad...
Maybe I put the cam in wrong with the lobe opposite to the correct way...
Shouldn't make any difference as timing would correct it...
I will get some easy start tomorrow...
I will win 👏

For the last few weeks I have been trying to recommission my G3L rigid. Its been at the back of the garage for 6 years and had lots of bits robbed off to keep my other singles running. The final step was a weak spark so I forked out for an exchange magneto from the club spares. Good fat spark. But it still would not start. Not even a pop or bang. Today I rechecked the timing only to find that I had managed to time it 1/2 an inch after TDC, obviously must have turned the wheel the wrong way once I had marked up the broken spoke as the timing rod. Reset it to before TDC and it started first kick.

No chance you have made the same mistake?

I remember when I was building my 36 AJS and found most of the carb. I had no cables etc. fitted. The carb had no air slide and was as found. Nothing removed altered etc. I just gave it a clean with petrol and loosely fitted in on the bike, nuts just nipped up by hand. It had no exhaust pipes. I had not touched the engine. I don't know why, but I just depressed the kick starter. There was a terrific bang. I was still wondering what the bang was when my wife came in the shed and asked what the loud bang was. Seems the bike just sucked in some petrol I used to clean the carb a bit and fired . So if everything is OK with your bike it should a least ignite fuel. It was 1986 when I was putting the 36 AJS together. When it fired. I found some 7/8" bars and levers made up cables , fitted them and the bike started first kick. 32 years later, all I have done to the bike is, found and fitted an air slide. Since then all its needed is clean points and plug ( old original type ) Also dabbed araldite on a punctured float. It will start with fuel left in the tank 2/3 years old. Have to remember its not too fussy about stale fuel. It only had 76 octane fuel when new in 1936. Perhaps that's why these old bikes seem to go faster than period road tests claimed. 95 octane fuel quite hot compare to 1936 fuel.

Thanks I keep going back to the timing..
I loosened mag cog on crank shaft (I turned rear wheel forwards (in gear) until both valves open, and piston at tdc (pushrods spinning) set A/R open with wedge against springs tdc marked with pencil, then I marked a line 1/2” above previous line and turned rear wheel BACKWARDS till top marked levelled with plug hole.
Then turned the auto advance ANTI-CLOCKWISE (towards the rear wheel) until points started to open.
Carefully replaced cog.
Exactly as instructions...
Please tell me book is wrong 🤲

mikeydpippin wrote: turned rear wheel BACKWARDS till top marked levelled with plug hole

Hi

I was originally advised and always have since, set the crank rotation in the direction of normal rotation, i.e. rotate the engine backwards past the BTDC point and then forwards to it. The theory being that this negates any backlash in the timing gear train. However I don't think this is going to cure your problem.

I think I'd be buying / borrowing / rigging up a system to gauge the output of the mag, (spark tester):



Regards Mick

Mick D wrote:
I think I'd be buying / borrowing / rigging up a system to gauge the output of the mag, (spark tester):



Regards Mick

It does seem that a weak spark is at the bottom of this.

Mike, have you followed Groily's advice? Even with mag in place and turned gently by the kickstart.

Groily wrote:I'd check first off to see if you can get a cracking 1/4 inch spark from the end of a bare HT lead to earth with a flick of the wrist on the armature. You should be able to. A plug gap isn't much of a test and you'll get a spark even if things are pretty late.

Don't rely on the Spridspark tester; they're rubbish......