Category Archives: Scotts

Scott Iron barrel machining

I already posted a picture of an iron barrel my father, Roger, has been machining up from one of his castings but he’s sent me some more pictures as he’s almost finished.


In his email Roger said:

Pics depict a newly manufactured iron block showing inlet tract arrangement where it must be noted that as the “Spectacles” portion of the crankcase will be removed, then this forms the upper ceiling of an enhanced inlet tract.

Note the two 10mm counter bores which are used to enable accurate poisoning on holding fixtures during the metal cutting processes and by using ring dowels (Sleeves) to accurately position the cylinder head which also has such features.

Ports timings are more advanced than standard DPY blocks, but less than the aluminium competition blocks I make to special order which still give much improved torque at low to medium revs.

Dies and piston blanks to make 500cc pistons are currently in manufacture as are another batch of cranks comprising 15 sets of standard long stroke cranks. 5 sets of standard long stroke cranks to be fitted with Tungsten weighting slugs, and finally 5 sets of a special heavy duty crank variant for use with ball bearing main bearings and incorporating heavy metal weighting slugs. These can be used in standard cases after appropriate modification or in the Moss high duty large inlet competition crankcases.

If you are interested then contact him at Moss Engineering.

Silk Scott racer project – the return of the frame tubes

I’m not sure that would make a successful Hollywood title but it sure as hell excites me!
I don’t know whether everyone does it but I carry moments of regret through life somewhere buried in a dusty box in the corner of my brain. They spill out sometimes and I go through an internal process of closing my eyes and shaking my head side to side as I remember the feeling. It is largely pointless of course as the moments are long gone.
The bike(s) I shouldn’t have sold, the engines I shouldn’t have blown up, the Rolls Royce I shouldn’t have crashed (it wasn’t mine.. I was working as a mechanic in New Zealand and being towed to a garage) and definitely in the mix.. the Silk Scott frame I shouldn’t have cut the front tubes out of. Putting the fact that it wasn’t going to be easy to swap engines without doing something ‘detachable’ aside… the Silk Scott sat rather forlorn for at least 10 years until I started looking at possibilities last year. It’s not finished by any means but Alan (Noakes), who’s been working on the detachable cradle has got a loose assembly together now. he just sent me the pictures: This is how Christmas should feel.

My initial sketches
My initial sketches
Frame connectors
Frame connectors
loose frame assembly 001
loose frame assembly 001
Frame loose assembly 002
Frame loose assembly 002
loose frame assembly 003
loose frame assembly 003

The next step is to braze the lugs up.

So that’s what Alan has been doing!

What have I been doing?
I’ve stripped the weighted cranks out of the crankcase my dad machined for the Silk Scott as I need to do some final work on the gas flowing on the transfer and inlet passages (I love doing this.. stick a MotoGP DVD on and needle file for hours). I’ve also written to Rex Caunt, an ignition expert, to get advice about the process of setting up a charging system using the ring of magnets on the side of the flywheel.

It’s all too much. I’m off to bed.

January 2015 – Progress report

Well, we are moving in the right direction (I think) but I’ve a lot of ambitions this year so we’ll see how it works out…

Last weekend I decided to drive up to Leicestershire to see Roger and to help him improve security at his place, following the break in the previous weekend that resulted in the theft of a Yamaha RD 350 LC YPVS F2 (the one I had when I was 18 years old.. 25 years ago). He’d bought lights and I bought an alarm system and over the weekend we fitted it all and made the best of a bad lot.
I love being in the workshop and he’s still pushing forward with improvements to machinery and tooling, the latest being a DRO on the beautifully made Smart and Brown 1024 VSL lathe. You don’t need them, but they do make life easier and quicker.
It’s also good to be surrounded by his Scott engine work and I think we help motivate each other to do the best we can to make sure that our racing Scotts are in good competitive order for riding this year.
Sometime on Sunday morning we had a visit from Eddie Shermer, the editor of ‘Yowl’ (journal of the Scott Owners Club) and a skilled engineer in his own right. He and his wife also put great energy into organising the annual ‘gathering’ of the Scott Owners Club held at Abbotsholme School in Staffordshire.

Eddie Shermer, Roger and Thiel 158 universal jig mill. They were smiling until the photo!
Eddie Shermer, Roger and Thiel 158 universal jig mill. They were smiling until the photo!
Eddie does a lot of Scott transmission work but also takes on complete engine rebuilds too, and came to discuss possible solutions to a particular problem he’d encountered with a crankcase. It was good to see him and always interesting to discuss the engine issues.
In fact, I kept a Scott line going through the weekend because I’d arranged with Alan Noakes in Lincolnshire that I’d take the Silk Scott frame up to him so that he could make a start on the frame connectors. Lincolnshire is hardly on the way back to Devon, in fact around 2 1/2 hours in the opposite direction, but it meant that I could see Alan and chat through some of the details and also see some of the things that he is working on. He had some hardened and ground clutch hub centres as well as pressure plates that he’d made on the bench, and also a very compact roller starter that he’d even cast the rollers for. Very impressive.
Anyway, I couldn’t stay long as I had a 6 1/2 hour drive back home! Just back by midnight.

This last week, I’ve removed the carburettors from the Super Squirrel as I need to make some modifications for the return to petrol. I never had the twin carb set-up developed for methanol anyway (switching back to petrol this year) so it’s not something that I wouldn’t have to do anyway. The two carbs are Amal 276, but are of different bore sizes at the moment. I need to get them bored out to 1 1/16″ and also have some short inlet ‘trumpets’ made. They won’t be very trumpet like, but will just have a better radius for the air flow.
I’ve also got some ‘K-type’ thermocouples which I want to fit to the exhaust, fairly close to the exhaust manifold, to give extra information when I take it to so a dyno setup when the inital carburettor modifications have been done. Petrol will make everything run hotter, and I’ll need to be careful to try to make sure that I do what I can to make sure that I’m not overheating the piston. I may also fit a temperature sensor to a spark plug to read that, as well as coolant temperature to see whether the small radiator is able to shed heat. It’s possible that I could pressurise the radiator to help the situation, but it might not be necessary. I also have a slightly rough, larger radiator that I bought many years ago from the late John Hartshorne, a prominent Scott enthusiast who had some wonderful stories, not least from his work with Wilf Green in bringing East German MZ’s into the UK in the years before the ‘Iron curtain’ came down.
Also on the agenda is crank counter-balancing. A Scott engine, being a 180° twin has reasonable primary balance, and normally they are known as being fairly smooth engines. They have almost no actual balancing on each crank assembly however, as the cranks are too small. The engine relies mainly on the large central flywheel to help dampen out the residual vibrations, which it does reasonably well. Some people have drilled the side on the flywheel on opposite sides to try to counteract the implied rocking couple effect but roger has never been convinced of the efficacy of this process. His own idea was to view each crank assembly in isolation and to work to try to balance at least as much of the big end weight as possible. In his ‘four bearing cranks’ he has two crank ‘discs’ each side, rather than the usual one. His enables him, using tungsten heavy metal (and Titanium rods) to balance the big end if nothing else. Rogers engine is very smooth, much more so than my own, and seems to want to rev more easily. We have ‘slugged’ single sided ‘Moss’ cranks in the past for a couple of people, and one of them cannot praise its smoothness enough. My cranks are not weighted, but I have some heavy metal slugs and I want to fit them. Normally, the holes are put into the cranks prior to heat treatment, as the final specification of the material conforms to around 50 to 53 HRC which is pretty tough stuff to machine. I’ve been looking into using surface coated solid carbide cutters rated up to 60 HRC to machine out for the slugs. I’ll post further information on the calculated % balance. I think it should be interesting!

Anyway, enough for now. things are happening! Even the Triumph head is back although a little more work needed here too.
I’ll try to not leave it so long as we go through the winter.

Recollections of the Silk Scott by Colin Heath

I was intrigued that former Scott racer, Colin Heath’s name had come up as a subsequent owner for both the ‘prototype’ racing Silk Scott

Silk Scott prototype
Silk Scott prototype
and ‘FNT’, the Silk Scott racer owned by John Farrar and co-developed with Alan Noakes and Barry Tin(g)ley. See Alan’s memories here.
I wondered whether this could be true.. did he really own both of these machines and what was the story?
Alan Noakes with FNT Silk Scott (1971/2)
Alan Noakes with FNT Silk Scott (1971/2)

Colin came to visit me a few months ago, as his daughter lives in the same town as I do, and upon seeing the picture of the white Silk Scott prototype on my wall noted that he’d owned it, having bought it from George Silk himself.
Only this week, Dave Whiteside contacted me to say that he’d bought it from Colin and that it was now in Sweden.

I thought I’d email Colin to ask about FNT, and he sent me a piece that he’d written for ‘Yowl’, the journal of the Scott Owners Club in 2005 but never sent to be published.

See the PDF 18. The Missing Silk Copy.

A wonderful insight into the work that people were putting into Scott engines at the time and the results!

Colin also sent me a couple of photos too, one of FNT’s engine and one of Alan Noakes taking off.

FNT engine
FNT engine
Alan Noakes opening FNT up!
Alan Noakes opening FNT up!

many thanks Colin.

Stafford Classic Mechanics show (Oct 2014)

The Stafford classic bike shows are apparently very popular and certainly this one was a good day out. Definitely oriented towards post vintage stuff and mostly 1960’s onwards really. I don’t go to shows that often, in fact the last time i went to Stafford was on my dad’s Ducati 750SS when I was 18 (he must have been mad). That’s 24 years ago. The best bit really was the opportunity to chat to the guys on the BHR (British Historic Racing) stand where Roger’s Scott was being displayed along with a number of other really interesting machines.
The Mogvin, a mightily impressive Vincent twin powered three wheeler with two wheels at the front and one at the rear drew a lot of interest and Robbie Browns highly developed 175cc championship winning BSA Bantam sounded fantastic when he started it up for a crowd.

The Mogvin
The Mogvin

Robbie Browns BSA Bantam in 175cc guise.
Robbie Browns BSA Bantam in 175cc guise.
Mark and Sue Whittaker, hugely enthusiastic supporters of the club and campaigners of a BSA outfit were displaying their temporarily worse for wear Enfield Bullet, which they lend out to people who want to try their hand at racing with the club.
Roger's Scott Flying Squirrel racer with Mark and Sue Whittaker's 'Bullet for borrowing'
Roger’s Scott Flying Squirrel racer with Mark and Sue Whittaker’s ‘Bullet for borrowing’

Tony Wooley’s purposeful Rocket 3, and a number of other club machines completed a very impressive display with Gerry Daine, John Lorriman, the Whittakers, my dad, Robbie Brown and others manning the stand for the weekend.
I started racing with the club back in 1988, but it’s neither been continuous through the intervening years nor am I as regular a competitor as I’d like. The best bit of the show for me was really the opportunity to talk with the guys on the stand. So much racing experience, so much tuning knowledge and such decent people. The BHR has still much of the family feeling to it that it always had. Sure, things change and the early classes aren’t as well supported anymore but I guess that’s what is bound to happen. Things change. Paddocks are still open and friendly to all who come to a meeting and anyone who fancies a go will find a welcoming reception.
There was one other notable thing which made my day.
They have a little ‘GP area’ which they bring notable bikes into so that the owner can talk about his machine and then they can start it up for all to listen to. Roger had been asked to show his Scott on the Saturday and the guy doing the interviewing, Steve Plater ( ex TT and NW200 winner) had given him the microphone. My dad occasionally likes playing to the crowd and put on a great show. I saw him present his bike on Sunday and I was very pleased to find that someone had videoed the occasion.

See the interview here.

November 2014-Moss/Silk Scott racer progress

As with all good projects, you need a certain amount of momentum to get over the tricky bits. The first tricky bit for the Moss/Silk Scott racer is to rebuild the frame so that its strong and aligned.
I cut the front downtubes out about ten years ago, as we had intended to make the bike work as a test bed for engines we were rebuilding. The problem was that you couldn’t get the blinking engine out without having to partially strip it, or that’s what I remember anyway. Maybe others (Yuri Gellar?) would have had better luck. Paul Dobbs, who raced Roger’s bike at the time, agreed with my suggestion that we could have a detachable cradle… so I cut the front tubes out. I’ve often regretted it, mostly because of the extra effort required to get the thing back together. With some intelligent work though, it could be a really useful modification and it’s time that I pushed to get it sorted out.
As Roger is snowed under with engine work (and welding and brazing were never his thing anyway) I’ve been talking to Alan Noakes, an engineer and a Scott enthusiast, about the best way to approach this. Alan has considerable experience with welding and brazing and also has a frame jig for the duplex Scott frame which may just work with the Spondon frame.

Another reason that it’s great to be working on this with Alan is the fact that he has his own history with the Silk Scott. He sent me a wonderfully atmospheric photograph of him with a Silk Scott set up for racing when I first contacted him and after some encouragement he gave me some of the background.

The Spondon Silk (see below) you have pictured on your website could be Georges prototype but it does not have the double sided Fahron front brake which I would have expected as the first one was raced in the Manx GP by Stuart Hicken 2 years running either 71/72 or 72/73, by the way I believe Stuart Hicken is MD of Mallory Park now, I did meet him at a vintage meeting at Crystal Palace after his ride in the MGP and he said he was aquiring Scott parts to build a vintage racer with Georges (George Silk) help but I don`t recall ever seeing him racing after that.
The story of the Silk Racer in the photo is this, during the 1960s I met a local Scott owner by the name of John Farrar, we were both intent on tuning our Scotts to make them faster we also used to bother George Silk at race meetings hanging round his camp asking stupid questions etc. at some stage John had his crankcase fitted with Silk cranks and we carried on experimenting with different mods and sharing information with George, I did the engineering John paid for it. When George and Bob Stephenson shared a stand at a race bike show in London could have been 71/72 george had his racer and the first road bike on display, John had decided to order a racing chassis complete with gearbox but minus engine as he would use his existing engine and placed his order at the show this is the bike you see in the photo, on the day the photo was taken you can see that the bike was not finished no exhausts etc. we just wanted to make sure that the gearbox and clutch worked I had modified a Jawa speedway clutch to fit. The letters FNT on the bike stood for Farrar Noakes Tingley, Barry Tingley was a Local rider quite good had been given rides by Stan Shenton from Boyers of Bromley who later ran team Kawasaki. Our first race with this bike was at a Big international formula 750 meeting at Brands with the likes of Sheene Grant etc. we finished well down the field the following week saw us drawing up a completely uprated engine with reed valves flat top pistons alloy cylinder and heads etc. I did actually start making some bits for this engine but a change of job put a stop to progress and by that time John had decided that Georges new Silk engine would be a better option for the bike. John eventually sold the bike to Colin Heath.

Alan Noakes with FNT Silk Scott (1971/2)
Alan Noakes with FNT Silk Scott (1971/2)
FNT Silk Scott racer with Alan Noakes. (1971/2)
FNT Silk Scott racer with Alan Noakes. (1971/2)
Silk Scott prototype
Silk Scott prototype

October 2014: planning for the winter in the workshop.

So, the last British Historic Racing club meeting of 2014 at Cadwell Park has been and gone. In our calendar that is the sign that winter is on it’s way. What normally happens is that you think you’ve got plenty of time to get on with your bike project(s) but all of a sudden, it’s Christmas. Then, no sooner than you’ve sung ‘auld lang syne’, January disappears too. You are then halfway through March before you know it and suddenly you realise that the season starts in April and you’ve a week before the first practice day and you are no-where near ready.
Even though I know this, it will still happen…

I had thought that the Super Squirrel wasn’t quite working as well as it should after the frenetic ‘development’ work I did just before the meeting, but was very happy that it was working at all. It certainly went well enough to be competitive enough to have some fun but I know it could be a lot better and it was with that thought that I took it to the dyno at the beginning of October.

October dyno run

Torque

Super squirrel torque curve - October 2014
Super squirrel torque curve – October 2014

BHP

Super Squirrel BHP curve - October 2014
Super Squirrel BHP curve – October 2014

Steve, who runs the dyno said pretty much immediately that he could see it was massively rich… so much so that it’s just not able to run anything properly. He’s up for a longer set-up session, and with that in mind I am now trying to get everything together that I’ll need.

I’d talked to Rex Caunt at Cadwell Park. Rex is a friend of Roger’s and it was with his help that we fitted a PVL system to his Scott many years ago. He went on to fit a BTH magneto and I inherited the PVL system.
Rex is not just an expert on racing ignition systems, but he’s also very much involved with two stroke tuning and we had a long chat about my plans for development. He suggested analysing the exhaust gas temperature with some thermocouples to give me some idea of what was happening. Pressure waves behave differently in different gas densities, so temperature has an effect on the speed of the wave. I picked some up really cheaply on ebay.
I also bought some new needles and needle jets as the one I did are not suitable.

Once I’ve got everything ready, I’ll be booking a dyno slot.