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.
My dad, Roger, has been working to make sure that as many new engine components are available as possible; pistons, heads, crankcases, cranks, transfer port covers are all available as new components. One of the items that he makes for the racing and sports engines that he produces for people is the cylinder block, normally in aluminium with hard chromed bores.
He’s got iron block castings but he’s not machined one up for years, but he was today and sent me a picture.
FNT
In the last days I’ve been contacted by the new owners of both the Silk Scott prototype and ‘FNT’.
FNT went through a period of development which resulted in the fitment of one of the early Silk engines, Georges own, Scott based design. In the intervening years it was forced into boxes for a little while, but is now in deepest Wales and being rebuilt for use on the road. The owner confided that he had some sense of guilt about that, but the various racing focused parts will be retained for possible future use.
The Silk Scott prototype
It appears that the Silk Scott prototype machine is in Spain now and seems to have remained largely unchanged. The owners have a collection of all manner of period literature and photographs which document its previous life and the Manx GP race in the hands of Stuart Hicken, who is now part of the management of Mallory park.
The machine is for sale on ‘Car and Classic’ for £25,000. I’m not running a classified section, but I thought it was very interesting to see all the photos and documentation that they sent me and I thought that others may enjoy it too.
As well as the images, the owner also sent a number of scans of period reports of the Silk Scott’s TT adventure, as well as other relevant information.
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.
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.
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 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.
Christmas is not without it’s delights when you’ve got a 2 year old daughter and a 5 month old daughter, but in my house we were all battling a bit with various virus cold/sinusy ailments and looking forward to all getting better and starting a brand new year. Unfortunately just as the New Year began, my dad has suffered an upsetting incident.
Somewhere between the evening of Sunday 4th January 2015 and the morning of the 5th, my father Roger had a shed broken into. They were obviously looking to steal garden equipment but realised that once they had carefully removed a glazing pane to enter, they could release the shot bolts holding the fixed side of the twin doors and swing the mortice locked doors open. They stole his 1990 Yamaha RD 350 LC YPVS F2, which was my first real performance road bike when I was 18. He really enjoys it as it’s lightweight and quick and comfortable.
We’re looking at security now of course, too late. At least we might prevent a repeat performance.
I’ve posted a message on a motorcycling forum, but it’s highly unlikely it will produce anything.
I got the invoice from SRM today to say that the work to re-commission the Triumph Tiger 100 bronze head has been finished. It’s all money of course but if they’ve done a decent job I’ll be so happy. It’s twenty five years since I took that head off to get fixed and there’s a lot of water under the bridge since then. I like a bit of continuity.
I spent most of my School lunchtimes at Owen Greenwood’s motorcycle shop in Loughborough in 1987/88. I had my first road bikes from him. First a Simpson 50cc and then an MZ ETZ 125. I have no idea how many times I fell off them but he did call me ‘crasher’ Moss at one point. When he had the Triumph bronze head valves seats built up for me and my Dad, after my first season of racing with the VMCC, I doubt he considered that it would take this long to get the rest of the work done. He’d have called me a ‘messer’ without a doubt, but I know he’d be pleased that I was eventually getting back to it. RIP Owen Greenwood.
I’ve got to get barrels bored but I’m sure I’ve got a reasonable pair of pistons somewhere. It won’t be phenomenal but it should be somewhere in the mix in the 500 class. I don’t think the short stroke Manx Nortons need worry though…
The other main thing the Triumph needs is some attention on the breathing, I’ve looked into non return valves in the past but never got it completely sorted. It always did cover the rear tyre with a fine mist of castrol R. Nothing to the rear of the engine will ever rust on this bike. I’m sure a concerted effort will bring success, although I have seen that from 2016 all road competition bikes (two strokes too?) will have to have a complete catch tank under the engine. I think a scraper on the sidewall of the rear tyre into a dangling bucket might work better. It’s no fun hitting oil though, so I’ll do everything I can to get it under control.
Time has been in short supply in the last couple of months and I decided to do some further work to the workshop to enable better spares storage and working area before I commenced on winter motorcycle work.
Actually, time is likely to be perpetually in short supply now we have two young daughters so it’s important to try and make sure that I can work effectively when I do have the time windows available. Insulating the workshop well enough to be able to heat it efficiently on cold winter nights was high on my agenda when I rebuilt over the last few years and this winter it should be a lot more inviting. I know that it’s a sign of a real man to be able to fettle a bike in temperatures so cold that he can only see what he’s doing through a mist of his own exhalations, but it’s a damn site easier to motivate yourself to put winter hours in when you come home from work if you know that you’ll be able to feel your fingers.
My dad’s workshop had a diesel heater (fed by the 1939 Triumph Tiger 100’s original petrol tank) but it never really worked properly and it cost him a fortune in diesel. Messy, expensive and not even very effective… hardly the holy trinity of a successful heating system! My day job is running a business that I started five years ago with another guy, designing and installing systems that involve biomass boilers, boiler stoves and solar thermal systems (as well as photovoltaic systems) so it was only a matter of time before I upgraded his workshop heating.
In the Autumn I installed a stove that burns pellets and simply has a blown air output through heat exchanger tubes that are heated by the flue gases. It’s not eligible for the governments attractive RHI (Renewable Heat Incentive) payments , which require a meter-able hot water output, but it’s relatively inexpensive and very effective.Roger’s pellet boiler… a more effective solution for his machine shop This did have a simple rear projecting thermo-couple to sense ambeit temperature but I upgraded it by connecting it to a wireless room stat somewhere more representative.
I’m not sure he’s wearing flip flops and sipping pina colada’s but he says he can wear the thinner of his red overalls when he’s working now! Also, cast iron machines are a pretty good heat sink and you need to keep the temperature reasonably consistent (and certainly the air dry) to avoid condensate build up. It’s good sense from a machine behaviour perspective, as clearances change according to temperature. This can affect accuracy hugely ; my dad has a story about a large machine next to some roller shutter door in a factory he once visited that was not producing consistently accurate results. Every time the doors were opened, blast of sold air chilled one side of the machine. The likelihood of it being any kind of issue when you are talking about moderate overall ambient temperature changes is slim especially when you take into account that these are manual machines, where measurement and adjustments are made on a job by job basis. The accuracy of a production machine is much more likely to suffer.
Anyway, what’s the plan?
I’ve decided that I want to try and get the Triumph back into the vintage racing fray, as it was always reliable, it has great character and it will give me another class. My dad raced it for years with great success and it was the bike that I first started racing with in 1988. It’s most recent incarnation was in it’s 680cc form, in which it is indecently fast, but it blew the right hand cylinder in two above the base flange at Cadwell Park in 2009. In 680cc form..Five years is a long time to have not got around to sorting a fairly small problem like that, but I’ve concentrated my efforts on the Scott and it had to wait.
Though I still want to concentrate on the Scott(s), I also really want to recomission the Triumph, this time as a 500. It will be the first time I will have raced in the 500 class since 1989 when I last raced it with the ‘small’ engine. I first wrote about the necessary work here. As part of this process, I have entrusted the old bronze racing head (£5 extra in 1939) to SRM engineering who work on Triumph engines as part of their core business. I’ve supplied the valves and they are doing the rest. Whilst I have stressed that I want a full seat width in the head (bronze does recess after a time)I have asked if they can do a multi angle seat cut and colsibro guides, which they will hone to the G+S valves. The inlet is actually a V240 Norton Atlas and the exhaust is a standard. The inlet isn’t actually a great profile behind the head, or so I’ve been informed by a gas flowing expert, so I might relieve it. I’m just getting standard springs, rather than stronger ‘racing’ springs for the same reason, to avoid to much hammering of the valve seats and loading to the rest of the valve train. thruxton follower block and followersbronze head, as repaired through Owen Greenwood in 1989It has spitfire profile cams and thruxton followers (wider foot and 3″ radius in a special tappet block) along with a small diameter exhaust and single TT carb give great torque at low revs. I think the narrow exhaust works to provide back pressure to stop too much fresh gas disappearing on the overlap. Roger used to own a Triumph Grand Prix which he always said very lacklustre in the torque department. Mostly he put this down to the massive exhaust running to a megaphone, but he never really rated the head design anyway. It was built for a generator after all.
The old Tiger 100 is a really enjoyable bike to ride, although the handling can be a bit sketchy with the bigger engine in, mostly because the power of the engine would bend the frame in the middle. I mostly solved this through revising the engine/gearbox mounting plates on the drive side. I’ve got to get a set of barrels bored for pistons and tappet block and then We’ll look at working that into the build schedule somewhere!
