Magneto drive chain.

[Harry44]

There may be a lot of questions as I pull the engine apart on my 18S Bearing in mind the idiots that have had their hands on and in this engine.

So I've just taken the magneto drive chain cover off and there's no oil in there. Should there be? also is there an adjustment for the chain?

[Stuoyb]

Maybe you need to get yourself a manual from the frequently mentioned archives.

http://www.archives.jampot.dk/

1. Grease for the chain - not oil, hence the lack of a gasket and the large hole behind the Mag. sprocket.

2. As per the manual, the Mag. platform pivots to adjust the chain.

[Harry44]

Brilliant thanks

[Rob Harknett]

I would certainly do as Stu advises. Get a workshop manual and a parts list for the bike. Having first made sure you do have a 1957 18S engine. Do not adjust the chain until you know how to do it correctly. Do not assume the previous owners that have meddled with the engine were right or wrong. You do need to know for yourself what is right or wrong. I cannot remember if you asked about the metal gasket under the barrel. If so there may had been a sinister reason why this was done, so need to find out why. Was it to try and seal the joint and why? Miss matched cases? lower compression / shorten stoke due to wrong piston fitted ?

[Harry44]

Yes. Sorry if it seems I'm asking daft questions, but, without doubt whoever worked on this engine last either through incompetence or an attempt to deceive has done a lot of things wrong. I'm an experienced vehicle mechanic but new to AMC bikes. So I thought I'd take advantage of the experience on here even if only to confirm my own opinions. The copper gasket under the barrel could be to lower the compression but why? The paper head gasket makes me think sheer stupidity. now I have the magneto off I can see how it was meant to be fitted that would allow chain adjustment.

In the next few days I'll be separating the cases as I have to fit a new big end bearing and as that means splitting the crank halves I'd welcome advice of experienced people there too.

Thanks to every one who has helped so far

[Tolly]

My advise before you split the crank cases is to make careful note of the valve timing marks. There are so many options out there especially if it's a bitsa.

[Harry44]

My advise before you split the crank cases is to make careful note of the valve timing marks. There are so many options out there especially if it's a bitsa.

A very good idea unfortunately when I took the timing cover off................... the inlet cam came out with it