Category Archives: Images

1960’s VMCC racing pictures from Cadwell

I was sent a box of 35mm slides recently, taken by the sender many years before at a VMCC Cadwell meeting. He thought it was the 1970’s, but I have an idea it’s the mid to late 1960’s because of the use of pudding basins and the car registrations. I might well be wrong. I have the use of a scanner and so have digitally converted them. They are a really interesting insight into the variety of machines being used back then. I’d like to identify the machines and the riders so if anyone can help with this or any other interesting information, please let me know.

The evolution of the Super Squirrel racer

I’m doing things backwards here. I realise that I need to give some more of the the original history of the Super squirrel and how Roger’s Flying Squirrel racer came about. As I said in the previous post, the Super Squirrel racer is really only just returning to having the potential of competitiveness that it did in the early 1970s.

Super Squirrel racer, prior to frame modifications (around 1971/2). Note Roger's Laverda SF750 production racer with race kit. An unusual racing stable.
Super Squirrel racer, prior to frame modifications (around 1971/2). Note Roger’s Laverda SF750 production racer with race kit. An unusual racing stable.
Roger on the Scott Super Squirrel racer (around 1971/2) racing at the New Brighton circuit on the Wirral.
Roger on the Scott Super Squirrel racer (around 1971/2) racing at the New Brighton circuit on the Wirral.
My dad, Roger, having found that the Scott was fast and competitive in racing was very much committed to finding the solutions to the bike’s shortcomings, namely in handling, gearbox and engine reliability.

The single down-tube frame of the Super Squirrel had broken once before at the seat post and had been re-inforced substantially. Tie bars had been created to give some tension to the lower engine and undertray (carries the gearbox on a Scott) mounts as the original lower frame ‘rails’ have to be removed to be able to race. Left in, they will dig into the track and have you off.

Later shot of Super Squirrel racer around 1973/4. Note lower rails removed , replaced by tensioned 'tie bars'
Later shot of Super Squirrel racer around 1973/4. Note lower rails removed , replaced by tensioned ‘tie bars’ and no silencing!
This did leave things a bit more flexible in this frame and he resolved that therein lay some of the problem. He was sure a stiffer frame would be a great improvement.
He addressed the handling issue by having a duplex frame made by Bob Stevenson of Spondon to a similar design and geometry to the Flying Squirrel, only using lighter tubing. To be honest, he’s always said that the duplex frame he had made didn’t actually improve the handling, but it did allow a bigger carb (because you didn’t have the single down-tube in the way) and it was quite a bit lighter as it was a welded construction and not lugged.
Years later it was Paul Dobbs, the talented Kiwi rider who suggested that he thought the handling could be improved by moving the riders weight forward.
Paul Dobbs in inimitable action over the mountain on the Scott at Cadwell park, 2005
Paul Dobbs in inimitable action over the mountain on the Scott at Cadwell park, 2005
My dad did this, moving the seat forward, and a big improvement was felt. In about 2010 he had the tank shortened to allow this to be more neatly contrived.
I also moved the saddle forward on the Super Squirrel when I re-built it, and swapped the ‘Brooklands’ style bars that my father favours with a set of wide straights that force your hands wider and make your body weight shift forward. The handling is far better for this, and actually I much prefer the extra leverage too.

The gearbox story is well explained in his story of the affair, here, and the pursuit of power and reliability were definitely linked, as the inevitable longstroke crank breakages inevitably took it’s toll on successive crankcases, prompting a decision to re-cast cases with better material and extra strength. Cases were redesigned to have larger transfer apertures and inlet port areas and cranks were re-designed to use the crankcase doors as an outer main bearing support to overcome the design flaw and material shortcomings of the original overhung crank.

The development of the Super Squirrel racer into the Flying Squirrel was not instantaneous though and it was largely about a substantial focus on re-engineering. In truth, that has consistently been the focus of his very successful Scott racing development work. In the process, he has developed his Scott to the point where some people even dispute that it is one. To me however, the Scott was Alfred Scott’s creation and he was a man of vision and ingenuity. He left the company that bore his name in 1915 and died in 1923. It’s impossible to look at the balance and finesse of those early shortstroke machines and imagine that he would allowed the bikes to have developed as they did, in both weight and fragility, had he stayed with the company.
To me the very spirit of the Scott is strongest in those machines where people have employed their skill and imagination to take the unique qualities of the Scott and develop them.
It is in the DNA of the marque and though I understand of course that there are those who have great enjoyment of their original machines, to me there is no Scott more a Scott than one that has been intelligently modified, and there is no Scott that can lay claim to having been been developed with more ingenuity, determination, focus and success according to its remit, than Roger Moss’s Flying Squirrel racer.

Waiting for the call...
Waiting for the call…

The Super Squirrel racer … where we are.

It’s not been the best couple of weeks for getting on with the Super Squirrel racer’s engine with both my wife and little girl both poorly and work being very busy indeed. A very good friend of mine also passed away, although this did rather contribute toward the quietness and patience required for gas flowing with riffler files.

So what is the plan?

A bit of history… In 2006 I finished re-building the old Super Squirrel racer and into it went a good Scott engine that I’d built with Moss crank. I sold this engine to fund another more radical engine build, and machined up my own head and heavily modified a Scott barrel to suit. I also welded up my own expansion chamber.
The crankcase I used had been a damaged case that we’d had welded, but had some evidence of cracks still remaining beyond the welding.

Anyway, I took it to it’s first BHR meeting at Mallory and it felt really strong for the first two laps, before it died. I didn’t really look at the engine until I’d pushed it back to the van, but when I did I realised that the damage was absolute to the crankcase. It was split in two and completely irreparable.

oh dear.
oh dear.

Upon reflection, the case wasn’t up to the job. I might have had some tiny amount of piston/ head contact too.. I know they were close as I’d had it before during testing and had worked to increase the clearance. The main bearing assembly was experimental and I think that also may have been a weakness. You live and learn and competition sometimes just brings the answers a bit quicker.

I had been working with my dad building the engines for a few years and I think this just happened just as I was going to move on to do a contract working to changeover a cylinder head line to a new head in the casting plant at Nissan in Sunderland. As I was not in a position to build another engine, my dad resolved to machine up one of his crankcase castings to at least provide a sturdy basis for a race engine. Into this he built the internals of the previous engine, and the new engine was badged ‘Phoenix’ in reference to it’s resurrection from the remains of its predecessor.

from the ashes...
from the ashes…

It was a fantastic thing to do for me.. I think because he felt quite sorry as I’d put so much work into the previous engine and also, that he felt that the far stronger crankcase casting was a far better place to start.

So I ran the engine for a couple of years, on petrol, and it kept going, but it wasn’t really competitive. It wasn’t really ‘tuned’, just solid and although I really enjoyed my bike, it wasn’t anything like as good fun to ride as my dad’s Flying Squirrel, which just had a sense of thrilling urgency that mine lacked utterly.

The catalyst for the major improvements that came was when my wife and I received a wonderful wedding present in 2011, in the shape of a new expansion pipe that my dad had made to fit by Gibsons exhausts in the South East.IMG_6831IMG_6828 My wife found this quite amusing. It was somewhat better looking than the one I’d welded up myself.. but did it work?

The first test came early in 2012 when we participated in the Prescott hill climb in aid of the blood bikes. With the same jetting as previously used with my old pipe I accelerated from the line hard and then pulled in the clutch quickly as it seized on the needle as I rolled it off.

We played around with it in the afternoon, changing plugs, altering the timing and jets but it just seemed to be running very hot. The next outing was at Lydden with the BHR club and we put in an extra head gasket to decrease the compression. It was still running a bit hot, but better… at least it finished a race. It really wasn’t quick enough though. I realised that I needed to make a decision.

It may be that the exhaust is not of the optimal shape and there may be a build up of heat because of this and not simply because it’s charging the cylinder so effectively… but we are not running a blank cheque development program (!) and so we needed to try and see if we could get it to work.

I figured I had three obvious choices. The first was to put my pipe back on. I did not want to do that .. It seemed such a retrograde step. The second was to work on getting the heat away. I’ve got a speedway radiator in the bike so a bigger one may well be much more effective. Also my dads bike has an aluminium cylinder barrel which also transfers the heat away from the exhasut port and cylinder head much more quickly than my iron block. Great. A new radiator would be about £1000 and a cylinder several hundred.

The third way was not popular with my dad.’Dope’ I said, that’s what I’m going to do, ‘run it on dope’.
The positives of methanol are that it really cools an engine and allows a far higher compression ration to be run than with regular petrol. Methanol also burns more slowly and that can make for a smoother and more progressive power delivery. On the negative side, it’s comparatively harder to get hold of, more dangerous to deal with and you need a much larger amount to run on. I’ve also experienced lubrication issues since I’ve used it, but it may be that some careful development may improve that. It also doesn’t give much warning in terms of plug colour if you are running lean. It tends to let you know by melting a hole in a piston apparently.

So it was that I invested in a barrel of your finest methanol and talked to a few people who had experience using it. By far the most useful contact was Roger Cramp, who used to race the highly developed Velocette that his son Ian now campaigns with the BHR. He had been involved in the building and development of an ariel leader that he had run on methanol as well as a Greeves. He confirmed the research I’d done about the necessary changes to ignition timing but also said to be aware that methanol was singularly averse to atomisation (at least when bucketing it in) and that high intake gas speed really helped. This encouraged me to stick with my smallish single carb to at least try out and see if it worked.

I decided on a huge 980 main jet and then measured the needle jet with a taper pin. I then put the carb together and drew lines on the needle at 1/4, 3/4 openings at the top of the needle jet and then worked out the dimensions of the needle at those points against the aperture open for air inlet. I ended up with a pretty severe taper on the needle, but it seemed to make sense.

I advanced the ignition by about 7°, closed the plugs right up and pushed. It fired up and it ran, albeit a little roughly, before I put it in the Van to took it to the last BHR meeting of 2012.

It was brilliant. The jetting seemed to work fine and there were no holes in the power delivery according to throttle position. The bike pulled and was so much fun. It felt totally different to my dads bike, but the torque and flexibility of mine suddenly made it feel like a completely different bike. It absolutely hammered the clutch though (as it does tend to with three gears) and I was up to 1am on the Saturday night stripping, releasing, filing plates and and rebuilding it.

2013 came and one of the first jobs I did was to rebuild the clutch with new GFS plates, laser cut. They were perfect really because I had to dremel each one to fit with abut 0.010″ clearance. The less clearance, the less hammering… My dad also had some pressure plate he’d had made out of solid, which didn’t flex like the original ones. IMG_3703These didn’t have the adjustable clutch actuation pins I normally used, which are a pain to set up. I made pins up instead from some silver steel and got them within 0.001″ of each other using a cordless drill as a chuck, a file, a dremel and some emery cloth.

We took it to a couple of track days, and then the last Cadwell park in 2013 and (with new 21″ racing tyres robbed off my dad’s poorly Flying Squirrel) managed a couple of second places and even a fastest lap. It was flying, although not in the league of Mike Farrel on his Rudge, who was really out on his own and un-catchable for us at least. You can lose a lot on the start as it’s difficult to get off the line with three gears when you’ve geared top for a long straight. Except for a CS1 Norton belonging to the famous Lewis family who’ve been campaigning Triumphs and the Norton for many years. I think everyone else runs four gears. It does make a difference.

I ended the weekend having blown three composite head gaskets and with the feeling that there was a bit too much piston slap noise, but apart from that it was the best racing weekend I’ve ever had at Cadwell. I also knew I needed to strip the engine and that I’d do some gas flowing whilst it was apart.

And that’s where we are!

Smart and Brown stripdown continues…

I’ve stripped the saddle off and have had the chance to see the good and the not so good.
The mechanism which shifts the main power travel feed to either the cross slide or the main saddle seems to be in really good condition and is a joy to behold.

Feed direction indicator on front of apron
Feed direction indicator on front of apron
In fact I think most things seem to be fine although I plan to diss-assemble, clean and lubricate everything even if there’s no actual damage.
Both the top slide operating screws and nuts are very worn though as well as a few other bits and pieces.
Fortunately, I’ve made contact with somebody who has most of the bits I need, which is great.
The saddle is worn though and I imagine the top slides too, so there needs to be some precise measurements of wear and then some decisions made about refinishing work.
This is a fairly big deal, but it can be sorted out.

I think when I’ve got the bits to repair it sorted out, then I’ll put a cover over her and leave her until the end of the season and just do some research on bed repair in the meantime. I don’t want to hurry this as it’s likely that I’ll have this lathe for a very long time. That’s my plan at least. Now I need to get back to the bikes. Really my priority has to be my Super squirrel engine, otherwise I’ll have nothing to ride this year. The Silk Scott racer’s frame is high on the agenda too.
Last week I picked up some 5mm MS plate to make some engine plates out of for the Norton model 18 and I have a plan for the Triumph engine…

Lathe inspection begins

Well, It has not been sitting in the corner of someones de-humidified workshop for 60 years with a dustcover on.

The cross slide and compound slide both had a bucketful of backlash, so I took them off last night to check out the leadscrews and nuts. I’ve stripped the cross slide completely and the leadscrew was pretty badly worn, with some damage which actually chased out the brass nut.

Cross slide lead screw
Cross slide lead screw
Amazingly I just found one on ebay(!) and snapped it up. I haven’t stripped the compound slide yet but I’ll probably do it tonight.
The next thing to do is to take the saddle off and look at the underneath.
Cross slides stripped
Cross slides stripped
Part of me really wants to strip the thing completely and have the bed re-ground, and scrape the saddle.. but that’s a reasonable amount of work.

Also I’ve found that the brass helical back gear drive from the main spindle is badly worn, but it might be ok. Wonder what the spares situation would be for that?IMAG0611

The more I look at this lathe, the more I like it. The details are superb.

Model M: forward/reverse
Model M: forward/reverse




The head question

I’ve been trying to work out what to do regarding the Triumph cylinder head. I’ve not built this engine up as a 500 for years and it’s not really a ‘bolt together’ job as it is.
I started racing it in 1988 and at that point it had the bronze head. It was the first geared bike I’d ever ridden and the first time I rode it was at a Cadwell park practice day. I remember seeing these RC30s screaming by me at every corner of the track. It was dangerous of course as novices (and especially ones that can only just ride a bike) are completely unpredictable. I survived though.
After my first season, we stripped it and realised that the valve seats were quite sunken by many years of use (no seats.. straight on the bronze)IMAG0522 so we asked Owen Greenwood in Loughborough to have the bronze head seats built up ready for re-working and in the meantime I ported an iron head for that season. I obviously enjoyed using the air grinder as I definitely took enough metal out(!). In one place the seat is thin enough that I worried about overheating. No multi angles, no finesse! IMAG0516 We ran that head for another season or two and then it didn’t get run again until I rebuilt it to take to the Beezumph in 2001. I should have left it alone but I was obviously seized by the desire to improve it. This seemed to involve skimming 0.080″ of the head and the barrel spigot in order to increase the compression ratio.Doing this causes all kinds of issues as you have to deal with the sealing of the pushrod tubes and the lengths of the pushrods. IMAG0517It was misplaced endeavour, but it probably was fun at the time. Unfortunately There wasn’t enough clearance and the substantial 1.5″ inlet valves (Norton Atlas if you’re interested) contacted the pistons. It didn’t result in carnage, but we knew that it wasn’t really running right so I only did a couple of sessions.
I didn’t start racing with the VMCC again until around 2008-ish, twenty years after I first raced with the club, and this time it was with the Scott, but the following year we rebuilt the Triumph with the big motor (680cc) so the 500 has lain unused and unresolved.
I think considering that if I had no other options I’d be justified in re-working the skimmed head, but I think I’d keep my life as easy as I can. It’s not like I have a lot of time, so I think I’ll stick to either re-doing the bronze head or an iron one. Time to get some prices for hemisphere recutting!

Roger on the Triumph  with 680cc motor in mid 1970's rounding Mansfield corner at Cadwell Park
Roger on the Triumph with 680cc motor in mid 1970’s rounding Mansfield corner at Cadwell Park

Richard at the September Cadwell meeting in 2008 (or 2009?) on the Triumph. 680cc motor fitted.
Richard at the September Cadwell meeting in 2008 (or 2009?) on the Triumph. 680cc motor fitted.

Triumph cylinder head

I’ve decided to rebuild the Triumph this year, after being working engine-less since the last BHR Cadwell meeting in 2009 I think), when the 680cc motor blew the RH cylinder apart just above the base flange at the end of the start/finish line straight at Cadwell, just as I was going into Coppice. Fortunately, being used to a two stroke, I’m pretty quick on the clutch and I just pulled off.
The 680cc motor is very exciting in the Triumph, as it does make it bend in the middle a bit and that trait is at the heart of more than one story.
Although I’d probably prefer to keep the big motor in it, a change to classes in the BHR racing has meant that the old vintage class (up to 1934) has been joined to the post vintage class (up to 1948). The grids numbers became too low to run them separately. This meant that whilst before you could get two rides in the vintage with the Scott and two in the post vintage with the Triumph, I have only the ‘up to 48’ class and the ‘unlimited up to ’63 class’ that I can ride with either.
I thought since I can do those four with the same bike, it would be nice to have the Triumph running as a 500 to run in a separate class.
I’ve got a 500 iron head that I over-enthusiastically ported when I was about 15 years old and then later (over)skimmed to increase the compression. It’s an example in iron of what not to do if trying to make a bike go faster. I could possibly recover it, but I do actually have an unmolested one and it may be the wisest thing to start again with a bit more care.

Me and Triumph at Beezumph 2009
Me and Triumph at Beezumph 2009