SR1 Magneto - what’s missing?

[markwhitelock]

I would like to put the correct SR1 mag on my G80S, I have the mag and the auto adv unit, but I'm struggling to see on the parts diagrams what else I need.



I see on the club shop that there is a rubber washer to go between the mag and the timing case, and I can work out how the adv unit screws onto the tip of the mag, but what other bits are there? There is a cutout for a woodruff key, is that needed? What screws into the three holes on the face around the spindle bit? How is the mag fixed to the frame/engine?

Apologies if these questions are too obvious to some of you! Happy to be pointed to a clear diagram somewhere - I can't find one anywhere that shows how the mag is fixed in place!

[clive]

no woodruff key. The screw holes may be because the mag is off a stationary engine, not needed on a our bikes. Magneto fits to the magneto carrier with 4 bolts from underneath. In addition to the platform you will need two longer studs and two spacers.

[56G80S]

It's less a rubber washer than a ring. It's purpose is to seal the gap between the rear part of the magneto chaincase and the magneto to stop water etc getting in.

When you get the parts Clive mentioned and fit everything together, don't forget that you should ensure that the mag chain runs correctly between the ATD sprocket and the cam sprocket. The SR1 mag platform will allow some adjustment across the frame but the head of the four mag mounting bolts in the platform are difficult to get to when the platform is in place!

Check the taper fit between ATD and mag. It is this that keeps the timing from slipping. Don't be tempted to overtighten the nut at the end of the camwheel shaft, it will snap. Don't ask how I know.

Johnny B

[Jdraper]

Thanks for this thread which may have answered another problem I had a year or so back, namely that the ATD unit (and hence timing) kept slipping on the taper. The spring shield and C washer are absent on my unit, so I guess that this would make it difficult to get the unit tight.

A quick visit to the spares scheme is in order..

Jeremy

[Jdraper]

While looking in the spares book it states that the magneto shield is for the model 16's only - why not the 18's?

Jeremy

[markwhitelock]

Does anyone know the sizes of the three screws that hold the bakerlite cover in place?

[56G80S]

Not offhand but be aware that the bottom single one is longer than the other two, if it's too short there's the chance of stripping threads as it may only engage to the first couple of turns. There is a paper gasket to go between the cover and the body (although I ran mine for years without and in both circumstances I usually put a smear of thick grease on the gasket or cover edge) and it's all too easy to overtighten the screws and crack the bakelite. They are NOT cheesehead but have a countersunk head like a standard woodscrew.

I use a smaller screwdriver so that I get less grip, rather like doing up small bolts and keeping one's hand close to the working end rather than using full leverage.

Johnny B

[ajscomboman]

Does anyone know the sizes of the three screws that hold the bakerlite cover in place?

I sent you the numbers from AMC Classic Spares yesterday, only Steven has them in stock.