16H magdyno drive chain

Previously richard_payne wrote:

If it's a '37 motor or indeed a 1938 type then it should have 42 links and each sprocket should be 15t - However, AMCs and possibly later Nortons have 16t (I think) sprockets....they can be used I believe but obviously only in pairs....

Previously richard_payne wrote:

If it's a '37 motor or indeed a 1938 type then it should have 42 links and each sprocket should be 15t - However, AMCs and possibly later Nortons have 16t (I think) sprockets....they can be used I believe but obviously only in pairs....

Hi Richard,

Both sprockets are 15t.

Regards

Hugh

Hi Richard,

The engine number is W82280 (on the engine and V5C)

I bought the bike 11 months ago, I have not yet had a factory record check

A Northampton Licences 'Documents Destroyed' document with date stamp 4th November 1964 states engine number as 57754

Regards

Hugh

Previously richard_payne wrote:

Hugh, the current engine is a 1943 ex-WD unit - broadly the 1936 pattern engine. It would originally have had the 15t sprocket / 42 pitch set-up.

Presumably you have got the mag platform levered fully forwards ? Did some cheapskate previous owner once run out of adjustment and put a half link in to replace a full one on a worn chain ?

I'm not aware of any alternative mag platform that could have been fitted to a Norton and if it is an MO1 then the spindle height is standard...unless someone raised the unit for some reason that I can't think of....

Hi Richard,

That is very useful to know what engine I have, many thanks.

A previous owner actually added a half link to make it 43 pitch.

Although we have filed away the front edge of the platform it still won't go far enough forward to fit the new 42 pitch chain.

(the spindle is still slightly rearwards of the centre of the opening in the chain casing...)

So it appears the mag / platform must just be mismatched ?

I have now asked Renolds if they can supply a new 43 pitch chain.

But I guess it's all part of the fun of owning an old Norton !

Kind regards

Hugh

Unfortunately neither 43 pitch chains or links for 'narrow link' 3/8th inch pitch chains appear to be available anywhere ...

So my only option now is to get the 42 pitch chain to fit !

Please find attached some photos.

Thanks

Hugh

Previously richard_payne wrote:

Hugh, the problem lies with your magneto platform. The casting number suggests that it's Norton but I've never seen anything like it...Maybe Trusty Tractor or something ???

The lug should be very smoothly but sharply radiused into the platform with no protrusions on the crankcase side. Yours seems to have supporting ribs on both sides.

It's odd as the overhang looks correct for a pre-48 engine.

Photo attached shows three variations - Post '48, wartime mazac and pre-1940.

Thanks Richard,

Les at Russell Motors advised the platform for a 1943 ex WD engine should be steel not aluminium ... he had one in stock so we bought it. It brought the mag forward which looked good ... but unfortunately the 4 holes in the platform had been drilled in the wrong place so when bolted together the lug underneath the platform (ie. for the long mounting bolt) did not line up with the mag ... so the mag sat at an angle across the bike. Les has today kindly swapped the platform for another one that looks a bit more accurately drilled so hopefully we will be up and running again quite soon (the phrase one step forward two steps back comes to mind ...). Regards Hugh

Previously richard_payne wrote:

Hugh, what a nightmare !

There was indeed a wartime economy change to a cast iron mag platform which was listed from engine number W78001 onwards. It will fit all '1937' pattern engines.

Fingers crossed for a good one next time. Did it look like old stock ? There are Indian pattern cast iron platforms on the market.

Hi Richard,

The cast iron mag platform was not old stock so I presume it's from India ...

The second platform from Les at Russell Motors was drilled okay ...

but we still couldn't get the new drive chain on because the base plate on the platform was too thick ...

Anyhow after a bit of grinding down we eventually got it all reassembled.

With the reconditioned mag the bike is now very easy to start (many thanks to Paul Wolf).

While doing the mag we also tidied up the bike a bit - see photo attached.

So thanks again Richard (and to Richard Cornish) for your help and advice.

Regards

Hugh and Trevor Kelly