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.
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 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?
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.
many thanks Colin.
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.
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.
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. It 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!