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Re: engine sprocket selection

yes - 19t

email (option): cas.vanderwoude@gmail.com

Re: engine sprocket selection

The standard sprockets for a WM20 solo are eng 19T g/box 18T. The military bikes were usually more under-geared than the civy models to allow for off road and slow convoy duties. A 17T eng sprocket is listed for a WD combination.

I think any M20 geared under the standard settings would be revving its nuts off. Over gearing an M20 to drop the revs is OK until you come to a hilly area. Ron

email (option): ronpier@talk21.com

Re: engine sprocket selection

So the question is, is 2 x 19 teeth OK, or should it be 18 + 19 ?

Or the other way around; 19 on the engine and 18 on the gear box - would that make any difference ?

Re: engine sprocket selection

There may be some other factors involved, if an individual bike isn't coping with standard gearing, it may have another problem which is causing a lack power, gearing it down may seem like a quick fix, but problems tend to get worse rather than better?

Rob

email (option): robmiller11(a)yahoo.co.uk

Re: engine sprocket selection

I was thinking along the same lines Rob. But Cas didn't mention any lack of power, just low revs in top gear However it's not usual for anyone to want to drop the gearing on an M20 Ron

email (option): ronpier@talk21.com

Re: engine sprocket selection

A longish stroke engine can't ever be 'revving too low' can it ? Is it the case that it can't pull top gear ?

If the gearing is standard (as it sounds to be) then it would be more usual to raise the gearing if there is no longer the WD need for low speed convoy and off road work.

M20s do seem to suffer from quite a jump between 3rd and 4th which leaves them running out of chuff in 4th or over-revving in 3rd on long inclines.

The relevant aspects might well be :-

Engine down on power

Extremely hilly terrain

Rider weight significantly above the 10 1/2 stone / 70kg / 150lbs sort of average that would have been found in the 1940s.

Re: engine sprocket selection

Rik

The relevant aspects might well be :-

Engine down on power

Extremely hilly terrain

Rider weight significantly above the 10 1/2 stone / 70kg / 150lbs sort of average that would have been found in the 1940s.


engine down on power - yes
hilly terrain - yes
I'm more like 220 lbs

I know I need a top end overhaul. In the meantime, I might try going down to 17t to see how that goes. Its not like I'm going to go on any highway trips - I have plenty other motorcycle options for that.

email (option): cas.vanderwoude@gmail.com

Re: engine sprocket selection

I remember the first time I rode my WM20 it revved it nuts off at 45mph it was fitted with a 17 tooth engine sprocket, I have now changed this to a 21 tooth bike will now cruise easily at 55mph with a nice relaxed ride I have seen 65 mph with this sprocket fitted but then its revving hard.Only the steepest on inclines will slow it down enough to warrant change down to 3rd.I wouldnt go back to std WD gearing...Dave

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