How to adjust ignition timing

Not sure which engine you are working on, but if the engine is rotated forward, it will turn the mag in it's normal direction and take up the slack in the timing chain and any related timing gears. And yes you are going nuts, but you are not alone. Furthermore, speaking from experience, it doesn't get better with age.

The primary (drive chain) is irrelevant, isn't it? The aim of the mythical Mr Haycroft (he who wrote expert testimony about every British bike on the market for 50 or more years) was to make sure the timing drive is all tight.

Thanks for that, Ken. It wasn't the timing chain I was fretting about, it was the primary. The bike is an ES2 so, from the primary side, the engine rotates a/clockwise. hence my long diatribe above. Cheers, George

No need to apologize. We all get to have our turn. When you set everything, if you are off a degree or two, you can adjust things a bit by opening or closing the point gap. Just a bit though, you want to stick as close as possible to whatever the recommended gap is. Opening the gap will advance the ignition and closing it will retard it.

Except you won't know if you are a degree out if you are sticking a rod down the plug hole! I used a timing disc on the engine sprocket and a dial gauge with the head off. But to be honest I don't think these engines are that fussy, someone else suggested taking the max advance a couple of degrees further so you can adjust the timing on the run to suite the conditions. You soon get the feel for when it's running right.

dan

Dan is right George. It is a simplistic explanation in the book to turn the engine with the rear wheel until you find tdc. At what may feel like tdc with a bit of wire down the plughole can be 3 or 4 degrees out. You need a timing disc, find approximate tdc, and ideally, but not necessarily, the head off. I have the tools to do it both ways if you want to borrow them.

Cheers. Ian

George,

If you've got a manual advance and retard mag then this becomes rather academic. So long as you set the lever to fully advanced when you set the ignition that'll do fine as you can play around with the A&R lever as the load on the engine changes. These engines are very forgiving as they are low compression, unless Mike Pemberton has worked his magic on it!

I've always used a wooden skewer with the two marks for TDC and 5/8" BTDC for my timing, but it is fitted with a copper wire loop to stop it falling down the plug hole!

Just do it and ride it!

Phil.

Agreed that the rod down the plug hole does not give TDC very well - but for a relatively long stroke British single it's a pretty good way to identify degrees BTDC. And avoids all the practical issues of removing primary chain case and then working out how to attach a degree disc when there isn't enough thread left on the crank - or even if there is I don't have the correct size nut.

Not only that - but we don't necessarily know which came first out of the factory development shop. Was the height they found best then converted todegrees to satisfy new-fangled ideas, or were degrees converted to height to be helpful to ownerssetting things up in the street?

And as Dan says - you can always set it a bit 'too far' advanced so you can retard it a touch on the road.

Another pitfall with sticking a rod, or bit of wood down the plughole is that it goes in at an angle; unless you have a centre plug head; in which case your 5/8" marking on the stick is not 5/8" btdc on piston travel, so you will be retarded; no offence meant!

All this 'oh it is near enough for a long stroke low compression single' can leave you with a hole in your piston. You know what they say - if a job is worth doing it is worth doing properly!

I timed it last time with a (home made) timing disc with 47deg (from memory) marked on it but I didn't want to go to the faff of removing the p/chain-case cover and engine sprocket bolt. The footrest retaining nut (or the long bolt) is a bit iffy and the fewer times I remove it the better. I agree the rod method is crude. My calcs show that 1/16" out is equivalent to about 2.9deg when measured from TDC down. I think I'm talking myself into remover the ruddy p/chain-case cover! George

heres my timing disc with very strong magnet to hold it to the crank . you can space it out if needed.

its ok George more so for primary chain side but i have used the smaller one you stick to an old cd as well for the timing side . as per pdf. directional

http://www.brightsparkmagnetos.com/downloads/TD01/ferkt839tjv4ng89v456ng455t.pdf

Thats the advantage of the the one on the mandrel. Again, I haven't tried it on a Norton, but used it yesterday on a another British bike. You just remove the oil quill or oil feed to the crank on the timing side and slide in the disc mandrel and snug it up. Here is one example of how to make a piston stop. http://www.voc.uk.com/net/docs/3.6/3.6-287-10.pdf