Moss Engineering

33 Kings Lane
South Croxton
Leics. LE7 3RE

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A few problems with the server and also being very busy has kind of scuppered recent updates but here we go..
        December 2006

WEBSITE NEWS: Check out the new Search box !
Just type in what you want to find information on and press Go!
and also ..
We put some video up of Roger introducing a film of some of 'Moss Machine Tools' final work.
Go to  the 'Moss Engineering' Section (top menu) to see this...


The winter migration of engine work has arrived in full force and we have about 10 crankcases sitting on the floor with the internals in the various stages...

It seems that there are still plenty of people undertaking restorations of machines that have lain fallow for years.

Also some very interesting finds keep turning up.. Recently Roger and a customer were going through the gentlemans shed looking for the relevant parts for the engine build he wanted, when Roger saw a gearbox end cover. The Owner didnt know that he had one of the very few 4 speed gearboxes in captivity.

A solution to the design fault that saw them recalled by the factory in the 1930's ( a selection problem that gave them the reputation of having 4 gears and 16 neutrals) was identified by Roger in the late seventies when he made his replica, and thus this original could be made to work properly for the first time in its existance.

If you want to read the Story of The Moss racing four speed gearbox, click here

We are currently working on the drawings for the new headstems to be made for the early Scott Forks (email us here if you are interested in this) and we are looking at a new design to allow ballraces to be fitted as main bearings to standard cranks and crankcases with the minimum of extra work. These have been used on our racer for more than 30 years with great success.

We seem to be doing a fair amount of crankcase requalifying work at the moment, with some pretty desperately damaged crankcases having life breathed into them. The main difference between the way we do the main bearings and the factory is that when they ground the cups bores they did it on a big internal grinder with the cups installed and by rotating the crankcase...

This means that they didnt have to get the actual housings in the crankcase absolutely right as the final ops were done in situ.  You can verify this by measuring the wall thicknesses of cups  that have been removed.  The  bores are always (on factory ground cups ) eccentric.

When cups are damaged though oil starvation or other reasons, or the case itself is damaged through crank breakage, we remove the cups, have any welding done that is necessary and skim the crankcase cup bores through together to ensure they are in line and parallel to the block face ( therefore with luck square to the cylinder bores! ). We then grind the ODs of replacement cups (already concentrically ground on the ID) that have been previously built up with chrome to suit the skimmed crankcase bores.

We then install the new cups with new shrink rings.


'Moss' high strength cranks

The New Cranks are going through the turning process and will be ready for the intensive heat treatment process by mid january.

 For Crank information see here.

Racing News

Rogers Racer

Well .. another thing we should have shown a long time ago!

This is Paul Dobbs' cache of pots aquired during the 2005 season. Unfortunately they will be redistributed early in the New Year!


Rogers racer is under going its most thorough rebuild for many years. The Engine is stripped for new bearings throughout and the
cylinder is being rechromed after 25 years!
The Frame has been sent for repair after a couple of spills this year, and with that has gone the tank which is being shortened to allow the seating position to be moved forward.
The Forks will be rebuilt, as there is a little slop in the bushes now. We have also had the castings polished and with a pair of decent guards and a paint job... It should look better than it ever has...
Oh yes.. and with a new exhaust planned it might even go faster too!

Richards Racer

I am working on my new engine for the coming season. It will be a challenge to see if i can get a bit nearer to the performance of Rogers bike but i think its possible .. I have one of Eddie Shermers twin carb manifolds which will enable me to avoid to limitations of trying to breathe through the single down tube and am going to modify the exhaust system to try and get the benefits at lower revs.


If you are interested in these.. contact us here

The later Scott three speed box is rugged and reliable, but any bike with a three speed box obviously has to have a broad spread of power!
The great power possibility of a two stroke is to try and use the exhaust to both aid scavenge and also to push back some of the exhausted fresh gas into the cylinder prior to closure of the exhaust port.
This has been known for a while now!
as the timing of this pulse is related to the speed of the engine:  The slower revving the engine, the longer the exhaust must be.

The Scott needs a very long pipe if this possibility is to be exploited!

The main problem is that any 'power band' you end up with, must be within the scope of a gear change, and by working to make your engine able to rev higher
( probably the most conventional method of power increase ), you run into a problem..

The higher in the rev range you place the power band.. the longer it must be to span a gear change and the longer you try and make the power band, the less strong the effect.
With a three speed box... i think youve really got to try and develop power as low down as you can.

So thats the plan..  make a pipe that makes it pull from its bootstraps and forget the rev game..

thats until i can get my hands on some more gears!

If anyone is interested in the theories behind Two stroke tuning...much of my reading time has been taken in the last months with the excellent book by Gordon Jennings 'The Two Stroke Tuners Handbook' and  in the front of the section on Expansion chambers he remembers something the Late Great Chief Engineer at MZ, Walter Kaarden, once said:

'You'll know when you have the design right because the chamber then will be impossible to fit to the motorcycle without having it drag the ground, burn the rider's leg, or force the relocation of one or more major components'

I have to recommend this book highly to anyone who has an interest in how things work..

In fact this book belongs to my Father, who has a bunch of notes to do with a talk on Scotts and tuning for the local Scott club in August 1974!

and as an aside.. i found the obituary for Jennings who died in 2000.

It had this wonderful excerpt:

Jennings wrote in the mid 1990s to a man who expressed to him his wish to be a writer, wondering what elements were needed to become one:

"On my 50th birthday, now long behind me, friends presented a cake that said, "Against all odds," which probably summed up my life fairly well. When you've been reported dead, twice, and none of your friends thought it necessary to check to see if the news was true, you have to figure you have been strolling a little close to the edge. Let me offer you some comfort about the accretion of years: If you live a long time and pay attention, you'll know a whole bunch of useful things; and you'll find, in time, that old go-fast guys have no wrinkles on the inside."        

We wish you all a Merry Christmas and good luck with the Winter work that so many of you will be doing...


Richard Moss © 2003

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