Moss Engineering

33 Kings Lane
South Croxton
Leics. LE7 3RE

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  DMS 1001 Sports Engine: History and Specification


I was given the bones of the old racer when I was 14 years old.  Having the bits for a Scott is a long way from having a bike and most certainly from having a racing machine, and so even when i began racing at 16 it was on the trusty Triumph T100, which was a lot easier to throw together!

The bike received sporadic attention over the years, mostly because I spent so much time abroad, several years travelling during which i was chief engineer on a coral reef research ship in the South Pacific.
During the last few years I worked steadily on the project until last Autumn when i decided it was time to really finish the job. It was during the off season of the Winter 2005/2006 that i built DMS1001.


I had bought a crankcase, which obviously had issues. The right hand chamber had had a rod go through and had been welded up. The case had obviously lain on its side in water for a time as the cup was rusty and unusable. Also the oil gallery to the right hand main bearing was blocked and the threads of the right hand 1/8" BSP thread were corroded. 

Welding chambers almost always causes misalignments and the faces were all requalified. The cups were than removed and the oil gallery was cleared. The 1/8" BSP thread was bored out and an insert fitted.
The cup bores were checked for ovality and then new cups were fitted and ground in situ using an orbital grinding setup.

The Crankcase was gas flowed and i broke through in the middle of the 'throat' of the chamber both sides.  This did not concern me as i wanted the best profile possible so i used Devcon F to seal the areas.
Since then, one patch became detached and i have replaced it with a more flexible epoxy compound. Following this, I have had no problems.
Viton seals were fitted with non return valves.
The Inside was painted red and the outside was polished.


The barrels are L/S 600 Iron bored out to take Silk pistons. Ports are blocked off to allow the pistons to be ported and the barrel has been shaped and contoured at great length to allow a smooth passage of gas into the ports.
A single bridge is removed to allow a less disturbed flow and apart from this no work has been done to change the port timings as this tends to take away the bottom end. The skirt has been relieved to allow the best flow of gas through the piston ports.

Cylinder head

The Cylinder head is a Moss high compression type. See here for details.


The cranks are Moss high strength units, and obviously carry newly manufactured and matched main bearing rings / crankpin bushes.
The cranks were chosen because they were previously damaged in an engine due to incorrect assembly and thus we decided to requalify these rather than use a new and thus more saleable set.
The damage consisted of a small crack at the bottom corner of one of the keyways caused by the key stopping the cranks from being seated correctly in the taper thus putting too much pressure on the keyway.
The tapers were reground and the cranks were in our opinion, functionally, as good as new.

see Crank section here


The Cranks were fitted with Aluminium bronze screwed roller plates which were made to act as end float thrust washers and also bearing roller plates. These are used in conjunction with Viton seals running directly in the mouth of the cups and on the cranks.


Con Rods

The Con rods were both completely refurbished top and bottom with the parent metal bores being honed before the newly externally ground main bearing ring and the ittle end bush were fitted.
The Big end was then ground in situ and the little end was bored to be parallel to it.
They were both assembled with big end cages.



The pistons are Silks and are fitted with little end control rings.


Transfer ports

The Engine is fitted with Moss high flow transfer ports.


The Engine is fitted with helicoiled front mountings and has rear flexure slots in the deck to facilitate proper clamping in the frame.

see here for details


The Engine has been run on one track day and also at the last two day vintage club meeting at Cadwell park at the end of September without problems except for the aforementioned epoxy repair.
The bike was equal to the 350 racing ducatis, and with a better exhaust design would have been even more competitive.
It propelled me to the fastest lap in the Novice race, which was in a field including Triumphs and 750 Norton and i cant take all the credit myself for that!

It has great compression and pulls well through the rev range all the way to 5000 rpm, with no significant vibration.

I have no dyno figures for this but would estimate a rear wheel 26/27 bhp as opposed to the 17/18 of a standard 600 Scott.


If we commissioned to build this engine for a customer. It would stand them at £3733.

This includes (standard available components):

Flywheel £150
Barrels (unbored but structurally undamaged) £150
Crankcase £350
Rods (bare) £30
Total :   £680.

Due to the repair work on the cranks and the crankcase, i am reducing this price by £333.00

My asking price for DMS1001 is therefore £3400.

I would be willing to part exchange some standard components as part of the purchase.

In my opinion the Weighted flywheel option we offer (see here) really makes a road bike and if someone were to pay the asking price i will strip the engine and do this for them. I will also laqueur the barrel before reassembly so the engine looks as good as new.

I am selling it mainly because i have some new porting ideas for next year and would have to change a lot of things to try them out.
This is a very high spec engine that has had a great deal of personal time spent, even above and beyond of that which i would normally be able to justify.

Contact me at if you are interested


                   © 2003

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