Words of wisdom:- You can tell a lot by a woman's hands.  If they are around your throat she's probably a bit upset.

John Grew's Vibations Continued:-

You may remember that in Chat 20 John left with a mystery involving the new Mikuni carburettor  Here is what he found and the solution to the problem.   Eddy.

The bike ran well, but my wife, Julie, who is my apprentice engineer, noted that the engine occasionally missed a beat on small throttle openings.   This was the only time one could detect a slight hiccup.   Larger throttle positions were fine, so we just rode around and enjoyed the general experience.  I thought that one day I would investigate in depth.  This came to a head though as the bike started to lose some umph at circa 14,000 miles. 

The usual checks were made, including the carburettor, but eventually I reluctantly stripped the motor to find a badly worn camshaft on all lobes.  I was bitterly disappointed, especially as I’d fitted proper filtration and high speed oil pump. 

I conducted some research and found the answer. 

Apparently lots of Commando camshafts were not up to standard.  My opinion was that in their haste to produce the Commando they had lost the old AMC metallurgy and heat treatment skills, recognised as a strength at the Plumstead factory.  The old Atlas cams were as tough as diamonds in comparison, so I tried to find a good second hand example.  During my search Tony Harris mentioned that I could have a camshaft from his experimental twin.  It turned out to be a Dunstall sporting camshaft that has the advantage of holes in the cam base circles.  Sod’s law dictated that Tony had “twisted” his wobbly crank the other way, so I had to cut and shut again to suit my crank timing.  I also tapped into the pressurised rocker oil feed and gave the cams a positive oil supply.  The camshaft is partially hollow and allows this.

I was really annoyed that I had to re-engineer another special offset camshaft through no fault of my own and dug a little deeper into the background of “soft” Commando cams.  A real Norton enthusiast in the States had also succumbed to soft cams in his Commando engine and with his engineering knowledge and contacts investigated further.  He borrowed a ‘Brinell’ hardness testing machine and went around as many of the Norton spares shops as he could a few years back.  He asked if he could test their “new” old stock Commando camshafts.  I can’t remember the exact figure, but I seem to recall that well over half were as soft as – well, you know!  It was perhaps some consolation to me.

I was keen to get the bike on the road, especially with the new sporting cam.  I had taken the opportunity to fit some second hand Atlas lower compression pistons as I wasn’t lusting after a rocket ship.  I hoped that a lumpy cam and low compression would produce a nice combination.

I was pleased with the new power characteristics, but that low throttle ‘hiccup’ was worse than ever.  There was still a good tickover and it went very well as the wick was turned up; a mystery indeed.

I did the usual things of swapping over coils, high tension leads, plugs etc, but no luck.  Then I had an idea of using my Gunson Colourtune Plug.  This is often treated as a bit of a gimmick and in fact I’d never used mine until now.  I replaced the right cylinder plug and with single Mikuni carb set to a fast-ish tickover had a look at the blue combustion process through the glass plug body.  “Blue, blue, blue” and so on; great.  When I replaced the left plug and repeated the process I witnessed – “Blue, blue, nothing, blue , white, nothing” and so on.  This was that longstanding “hiccup”.  I reasoned that the new sporting camshaft’s increased valve overlap exacerbated the problem of using only one carburettor on an engine with out of step piston strokes.  One induction pulse was robbing the other cylinder of mixture.  Larger throttle openings weren’t affected by this bias.  All I did was fit two old concentric carbs and bingo, problem solved. 

I had actually thought about this when I originally fitted a single carb, but my reasoning was that Harleys and many vintage V twins used a single carb.  They had uneven firing and induction pulses, so mine should work in theory.  I later read an article reinforcing my later findings in that a second carburettor was necessary to obviate a mixture bias from overlapping induction phases.

So was all this a success and what is it like to ride? The bike has now done circa 20.000 miles.  It sound like a V twin and the high level exhaust I made isn’t noisy.

The secondary vibration has disappeared, so there isn’t any high speed tingle vibration.  It does still vibrate, but this is diminished and is like a single engine’s “thudding vibe”.  Irving hoped for a 50% reduction in primary vibration, but later estimates put this at a 40% reduction.  One observation is that all the bulbs are still intact.  Nothing has fallen off and nothing has cracked, despite some prolonged spirited riding including a flat out “demonstration mountain course lap” at one of the Manx Grand Prix classic events.

Coming from an engineering background I have often wondered how some of the more complicated metal shapes are made.  Here John Goodall gives us the answer.  Eddy.

Metal Spinning and use in vintage motorcycle parts.

My last full time employment was working for the National Grid Company a successor company ensuing from privatisation of the CEGB (Central Electricity Generating Board) in the 1980’s into several separate companies. I ran a site with a central stores and three teams one of which carried out overhead line maintenance, the second sub station remote control wiring and interconnecting etc., and the third a mechanical engineering workshop based on the premises housed on the Old Power station site and buildings built in 1939 to power Loughborough. This all served the Midlands Region at the time. One of the activities in the workshop was to manufacture control desks and cubicles for the power industry. Some instruments needed housing in specially made round top hat section containers fitted into the main structure for protection and these were procured from a company of metal spinners in Shepshed near Loughborough.

I used to visit the spinning company and got to see spinning actually taking place on the antiquated machinery. The machines used were like a large wood turning lathe with a high end load capacity as well as radial and the usual tail stock. The tools used were all manually operated and supported on a flat bar with two or three vertical bars, which allowed the hand tool about two feet long to be levered against these bars to bear onto the work to be spun. A flat plate to be worked is pressed by pressure pad from the tailstock onto the end of a usually steel former of symmetrical shape. The tool is applied and working from the inner diameter outwards the metal is worked over the former?  A soap lubricant is used to prevent pick up and welding of the metal component to the tool made from HSS. The more malleable the metal the easier it is to form and the process inevitably causes work hardening, which often means annealing the metal before the work can proceed. Some materials such as brasses and aluminium alloys often can be finished without this need. I have attempted to metal spin on my own lathe and the loads are such that it is difficult because of the great leverage needed and the speed and end thrust capacity is insufficient and I concluded it is not worth the effort apart from being very difficult. I did manage a few simple jobs, but nothing worthwhile.

I realised the process could be used to advantage in producing parts for some of my vintage motorcycle parts that had become very difficult if not impossible to find. I found out what sort of tooling was needed to produce magneto end covers to start with and being an ex-toolmaker set to and made the chucks to suit Miller and some Lucas Magneto points covers. I had them made in brass as it can be plated nicely and would not rust like some Lucas and other makers parts in steel. I started to hawk them round the vintage bike jumble sales and one day the late David Earnshaw came up and being his usual witty self said “I see you are in a spin again”.  Then he said that’s what you should call yourself and so “Inaspin” was born. Things progressed and I advertised in Old Bike Mart. The late Ken Hallworth asked me to do an article which I did and soon orders and enquiries developed into many other projects. I ended up making Miller and Lucas headlight rims, a few headlight shells and Riley side lights complete with bayonet fittings. All parts being metal spun with some other operations often being needed like knurling the rims of Miller points covers. Making the parts for the Lucas bayonet fitting headlamp rim and Riley side lamps etc. Another item I must have made many hundreds of were License holders in brass, I show the original for them in my pictures. This comprised two spinnings with a riveted on fixing arm and the cover held on with four SS screws and nuts with spring washers.  I went so far as producing special rubber seal to encapsulate the glass and license disc to keep things dry. The VMCC took these on for resale for some years.  Some special projects were made for the Douglas Owners Club spares scheme notably wheel bearing dust covers and even fuel filler caps. Norton clutch covers from 1929 were also made in aluminum just like the originals, Another was Vincent brake dust shields. I made hundreds of them for a well known Vincent parts supplier in Wales. ( I think?)

 
1. Villiers and Bantam mag covers, horn flares, bell mouths, points covers.                   2.Parts I replicated plus one spinning                                

 
Tooling for points covers and bell mouths etc.                                                     Model plane spinners, cowls, etc          

The business was taken on by my son Paul who ran it off my tooling for some years, but it eventually foundered when the spinners decided to run down their work pending retirement and now it is virtually dead, although I still have a few parts left to illustrate the possibilities. The basics that are needed are a symmetrical shape that is not re-entrant. For instance if your part is waisted and reduces in diameter from the spun end it will not come off the chuck or tool?? In industry they got round this by making the chuck sectional with a series of tongued parts that held together and could be dismantled by removing a key piece from inside the finished tool/spinning and then the other sections could also be removed. This was very expensive to make and beyond what I could produce with a lathe only which is all I had at the time. This was really needed for headlamp shells, but I made the reduced forward nose part where the rim sits as another spinning and then joined that to the rear part by soldering. Each part could be removed from its tool without problem. Most materials can be metal spun, but some are very difficult to spin like Stainless steels, which need constant annealing even with special high ductility spinning metals. Modern spinning is done as I understand it on CNC controlled machines using so called “Air Spinning”. Here hydraulically controlled rollers are used whose path is steered by CNC to form the inside curve, or shape say of the part with external rollers forcing the metal against them to produce the part. Very nefarious and difficult to imagine I have never seen it in practice.

My interest in models led me into making spinners for model aircraft, fuel tanks and cowlings for enclosing radial engines in scale models. One of the last series of jobs I produced was for the head lamps and wheels made in two parts for the Austin pedal cars for John Dumelo in Burton. John apart from working in the family Stove enameling business is an avid enthusiast of all cars and pedal cars and a keen cyclist as well.

 
Tool and spinning for a DC3 model and spinner chuck in alum.               Acetylene rim and alloy reflector, Douglas parts and misc.    

In summary metal spinning is a very cheap alternative to press tooling where the component is suitable, or where with some ingenuity you can get round the re-entrant problem. and the only difficulty today is that the traditional Metal Spinners themselves are disappearing fast, like most engineering skills in this country unfortunately.  John Goodall.

Words of Wisdom:- A recent study has found that women who carry a little weight live longer than men who mention it.

Ariel VNH V twin update. Pt 1. A little History

 I thought I should write an update on the Ariel VNH 700cc which I started and sent into Cheval some years ago.

First I thought I should remind those who read about it the first time and for those who have no idea what the VNH is a reminder of how it started before I get into where I am now.

During the early part of Jan 2007 I thought I would challenge my self and attempt to build a V twin engine based on a pair of late 50's Ariel top ends. At the time I had a small engineering factory making electronic magnetos under the BT-H name, so had CNC facilities and lots of other toys to play with.

I first designed and drew an engine on my CAD, but the problem was the crankcases. A few months later in June ‘07 an advert appeared in the Ariel club magazine from one Adrie de Graff in Holland.

Adrie, being very creative had made a V twin engine by welding two sets of damaged Ariel crankcases together and bolting two sets of iron twin port heads on in a V twin pattern.

However, there was no insides and he wanted somebody (mug) to finish the job off. The only thing he wanted was a ride if and when it was finished and everything was free.

I quickly wrote a begging letter off and convinced him I was the one to do this.  Fortunately, I was chosen one to do the job. To my surprise the motor was in Northampton, only about 35 miles from me. I also had to get it quickly, as the guy who was custodian, was emigrating in a week or so.

After acquiring it I found out the heads and barrels had to be returned to the owners. This was not a problem as I didn't want them anyway. After a lot of looking and thinking I decided to contact Adrie and ask if I could make the welded castings into patterns and cast some stronger cases with certain parts built up for strength and machining purposes. If you can find June and July 09 Cheval the long tail is in there.

Machining the new crankcase casting

 
         New cam gear arrangement                                                                       Checking timing                      

The end result was finished and fitted into a Norton F/bed chassis and it fired up first kick, yes it did, really. The motor had a few small issues and had some updates but the basic thing did about 2000 miles in this form.

 
 The completed engine fitted in a Norton Featherbed frame

Life and time goes on as we know and the intention was always to fit the engine into a mid / late 50's Ariel cycle one day.

A couple or so years later John Mitchell (Ariel magazine Editor) advertised a complete mid 50's NH which was last on the road in 1974, according to the tax disc. I snapped it up and as John was passing my way he kindly dropped it off at my house. As before, time passes and by this time I had taken the motor out of the Norton Featherbed and used the frame for another project and the engine sat under the bench while other projects and life passed by, including early retirement in 2011.

In the meantime the original log book for my donor bike had been acquired but little else in the way of progress until the middle of 2018.  I decided to do some alterations to the engine.

When I cast the crankcases I had 3 sets made. The second set of cases were made into an engine based on two ES2 Nortons. This had a different drive to the cams and the capacity was over 1000cc. I also made an Egli type frame to mount it in and fitted and electric starter. This is another story though.

The experience I gained on the second engine gave me ideas for the VNH Ariel so next time I will tell you about what I have done in the interest of a better engine (I hoped ����).  Tony.  To be continued ......

  ....and before you leave just another few  Words of Wisdom:-  Everyone has the right to be stupid it's just that some have abused the privilege.