AJS & Matchless Owners Club

You are aware that the disc will then turn at half engine speed?

Is that exactly half and will that affect the 39 degrees?

Generally a degree disc is unnecessary, if the timing is roughly where it should be by sticking something down the plug hole, try your normal starting technique a couple of times, then give it a big hand full of throttle and try again.

Yes exactly half

Thanks for your thoughts Duncan. If I were to try my method would I be looking for 19.5 degrees? Sorry my brain is currently in mush mode.

I notice that young Spriddler has suggested in other posts 7/16" btdc due to modern fuels. How do you feel about this?

Sounds about right, but your margin for error will also be doubled (1 degree out will equal 2 and so on), most find tapping the cam sprocket the most effective way of setting the timing as it avoids damaging the mag with an over enthusiastic "tap", you may struggle to do this with a timing disc on it.

I was going to connect the disc to the lower cam sprocket. I see what you mean about the margin for error. Stick down the plug 'ole it is then.

Edit: Scrap the above, I realise what you mean now tapping with a knocking stick as opposed to tapping a thread!

To be honest I have never had to reset the timing on my coil ignition 350 in over 25,000 miles it still is as the previous owner set it (have had to change the points though). My 37 250 is set to the book (with a piece of wire in the plug hole) and is a lot more sensitive to the A/R position when riding.

Thanks Duncan, your help and advice is much appreciated.