timing up model 19 after mag rebuild

Easy enough, I put a timing wheel (printed of the inter web) on the crank, set it at tdc with a dial gauge then adjusted the mag to maximum advance using a cig paper, but no doubt you could use a bulb and battery!

Bulb and battery won't work with a magneto.....

These engines aren't too sensitive to timing. First of all set the points gap which is usually .012". Make sure the mag is set to full advance, use a timing stick in the plug hole marked with max advance (I believe 11/16" for your Model 19), make sure you're on the compression stroke (very easy to get this wrong!), put in top gear and use the back wheel to rotate the engine.

Then use a cigarette paper (I actually use a piece of kitchen foil) between the mag points and set so you can just withdraw it.

It's not as hard as it seems......

Bulb, maybe not ..... but you can use this http://www.davelindsley.co.uk/magneto-timing-detector.html. ð

To answer a some of your queries, Jonathan; don't forget as you retard it the spark gets weaker so starting is a matter of judgement as how far you can advance it before it kicks you over the tank. Same with idling, ease it back till it sounds right. As to when you're riding, mostly you'll be on full advance. I tend to ease it back at traffic lights or if I'm slogging up a hill and couldn't be a***d to change down. You can usually tell by the sound of it whether you have it set correctly. You'll also get banging out of the exhaust on the overrun if it's too retarded. George

I've set my (side valve) further advanced than the book, and painted a pair of dots on the lever at the book figure. That allows me to play with it a bit. Frankly it's not all that sensitive to the odd couple of sixteenths of an inch around the correct figure. And you mightfind different figures in different books - in which case I'd choose the most advanced and then you can use the lever to bring it back if you want to. If they are too far retarded they lose power quite a lot, and overheat and blue the exhausts very quickly. Mine are blue...

As George says, you don't want it to kick back. But that will happen occasionally (we all make mistakes...). But once you get it running you'll find it will probably stop if you fully retard the lever. So it follows that it might not be possible tostart when fully retarded. You'll soon work out the foibles of your own machine.

Are you near an NOC branch? There's bound to be a nosy member who'd enjoy helping you get going! Or at the very least you'll find someone to talk you through it.

Previously George Phillips wrote:

To answer a some of your queries, Jonathan; don't forget as you retard it the spark gets weaker so starting is a matter of judgement as how far you can advance it before it kicks you over the tank. Same with idling, ease it back till it sounds right. As to when you're riding, mostly you'll be on full advance. I tend to ease it back at traffic lights or if I'm slogging up a hill and couldn't be a***d to change down. You can usually tell by the sound of it whether you have it set correctly. You'll also get banging out of the exhaust on the overrun if it's too retarded. George

George, thats a snippet of info I'm not aware of; "the spark gets weaker the more you retard", can you enlighten me?

Previously Dan Field wrote:

Bulb, maybe not ..... but you can use this http://www.davelindsley.co.uk/magneto-timing-detector.html. ð

Yes but you can buy a lot of fag papers (or foil) for 40 quid.......

Previously jonathan_newton wrote:

Previously George Phillips wrote:

To answer a some of your queries, Jonathan; don't forget as you retard it the spark gets weaker so starting is a matter of judgement as how far you can advance it before it kicks you over the tank. Same with idling, ease it back till it sounds right. As to when you're riding, mostly you'll be on full advance. I tend to ease it back at traffic lights or if I'm slogging up a hill and couldn't be a***d to change down. You can usually tell by the sound of it whether you have it set correctly. You'll also get banging out of the exhaust on the overrun if it's too retarded. George

George, thats a snippet of info I'm not aware of; "the spark gets weaker the more you retard", can you enlighten me?

Magnetos work best at a single point in the rotation where the flux density is greatest. They are set up so that this coincides with maximum advance as this is where the engine will spend most of its time. Retarding the mag puts the points opening away from this most effective point thus weakening the spark.

Not a problem with a mag in good condition but it is when it gets a bit iffy.....

Hand gear changes aren't the easiest devices to use especially on down shifts where you wish you were blessed with an extra arm. So you can retard the ignition in a higher gear and the flywheels will often pull you over the summit without the need to change down.

Riders in the 20s and 30s were much less keen on gear changing before the positive stop footchange came into general use.

Normally for starting you would retard the lever about 1/3 of its full travel but you soon discover what your own bike likes.

Thanks Ian. Saved me dashing to my books to check where I'd read it! George