The first thing to do is lighten everything throughout the engine, but not compromise on the strength and reliability of the working parts. The project was carried out by me to contest a Ducati Mach 1 in a two stroke class racing against Yamaha TDIC’s and Suzuki T20’s, and to attempt to beat some of the modern single cylinders in the National single cylinder championships. The only way to contest an old Ducati is to make it rev like it’s never revved before i.e. 13,500 RPM.

To make the machine competitive in all of the classic lightweight classes is to shorten the stroke by 4mm. I shortened mine by the same and used the 350cc barrel and piston which brings the overall cc to 236.

The standard Conrod was used as the steel ones are stronger and more reliable. The valves were enlarged considerably but the standard valve seats were retained but re-cut to suit the new valves; the valves were also machined to give good gas flow. To make the valves snap open and closed quick enough, stronger hair springs were fitted. The wire gauge of the springs is 156 thou thick. These were operated by red and white cam. If one uses too light a spring one would experience valve bounce.

The compression ratio measured with a burette was 14.5 to 1. Although I could measure 21 to 1 without a head gasket but this would compromise reliability and I would have to cheat using octane booster and any over revving would be detrimental to performance and reliability. The valve to piston clearance was measured as 050 thou using Plastigauge. I failed to mention the 350cc piston was highly modified by welding and re-cutting the valve seat pockets. The piston had to be modified due to lack of compression and the crown shape was wrong.

What I wanted the piston to do was to squish as much fuel without detonation but to burn everything down to the top compression ring. This is important as a lot of fuel sits just above the top compression ring being un-burnt and passing out through the exhaust port. Detonation is in many tuners minds, a bad thing to happen in an engine but this is not so as long as it is controlled. Head profile and piston crown clearances sort this problem out.

To attain top revs it is paramount to lighten all rotational weight. The thing to do is remove the Magdyno from the end of the crank and make an outrigger bearing in the primary chain case to support the crank, saving it from whipping at high revs. The next step is to look at lightening the gearbox; this is easy as all of the gears are thicker and heavier than they need to be. All of the gearbox gears can be lightened in two ways, drilling and machining on a lathe the skin hardness can be broken using a correctly sharpened masonry drill once through the surface hardness of a gear, the inner metal is like butter.

After weighing the gear train and subtracting what you have machined and drilled out you should have saved about 1.5 pounds in weight. Another critical part of the fuel burning process is the exhaust system design. The ideal length through calculations is about 9 1/2 foot for the header pipe and the silencer on the end amounts to approximately 13 foot long.

Having access to a Dynonometer to test the machine on, I found I could use the standard header pipe and develop a silencer to come within length and decibel tolerances to give maximum performance. A machine goes no where without correct carburation thus the standard Ducati carb could not live up to the demands of the drastically modified engine. Something more suitable was an Amal concentric as this carb has more scope for fine tuning and ease of obtaining accessories and upgrades. After all of the modifications it is a good idea to set the carb on the rich side so as to control detonation.

The ignition system is controlled using Rita ignition and a dyna coil with twin plug leads. The reason for the twin lead is that I have fitted a 10mm spark plug near the top bevel thus producing a twin plug head. Another important point to take into consideration is to modify the inlet tract so as to make it as straight as possible, you will find that when this is done that there will be a break out in the cylinder head. All you have to do is either weld the hole up or use Devcon aluminium filler, after filling, blend the inlet tract in. another important job is the front brake, I employed a Suzuki GT380 disc and callipers to produce a unit that I could use for very late breaking into corners.

A fairing was fitted to save about 2 horse power of wind drag and a low seat with minimal padding was used so as I could paddle start the bike. I have not gone into too much depth regarding all of the tuning modifications as I don’t want to bore you, the reader. But if you have any questions I will be happy to divulge the finer points.

The Ducati, when finished, should start with ease after a couple of paddles, you don’t have to stand by the side of your machine and bump start it. Prior to a serious race you will have to heat the engine oil up in a saucepan over a gas burner and pour it into the engine. The bike will also need a new plug fitted after it has been heated over the burner. The engine has now been primed ready for the start line without having to warm it up.

As with all Ducati’s, road holding is steady with warnings from the frame when it is being pushed too hard. In classic racing I use Dunlop KR 124 tyres and in modern racing I use Dunlop KR108 cut slicks. Both tyres work admirably in wet weather but the KR108’s have the edge due to there softer compound. All in all, the Ducati ultra, ultra short stroke is still a championship winner!

Terry Ives restored Ariel Red Hunter 1958 built at Stotfold Engineering

When we require a classic motorcycle restoration to be undertaken by an ‘expert or professional’ motorcycle restorer we have to expect the complete job to cost more than the classic bike is worth. This is a very common occurrence. There are ways to bring the cost down and keep them under control to make the job more cost effective.

Motorcycling is a passion to many and to keep a motorcycle in working and running order it can cost, over the years, many times more than the bike is worth. A 30 year old bike may have had a couple of re-bores with new pistons to suit, new valves & guides, new bearings & bushes, brake linings, as well as all the usual stuff that wears out like tyres, chains, sprockets, brake pads and lubricants. When we add all this up a £1000 bike has had at least £2000 spent on it. We don’t seem very conscious of this expense due to it being incurred over a period of time.

Say you own a Triumph T140 Bonneville that wants restoring. The complete bike has been languishing in a leaky damp shed and covered with a tarpaulin causing it to sweat, or maybe you you have just purchased it as an easy restoration project. You take the engine out and think about giving it to a specialist Triumph restorer, but before you do this bare in mind what I am going to tell you.

The Specialist

Firstly before you hand the engine over to the mark specialist it is worth bearing in mind that all engines work basically in the same way; they have a spark generator, pistons, con-rods, crank, and  cases which sometimes have an integral gearbox. The mark specialist knows his engine building off by heart, he does not need the ‘Haynes’ manual and he will bill you for his ability in not using one. His restoration job is easy, he may have a stock of secondhand as well as new parts he has bought in for future rebuilds. All these parts are paid for through your engine rebuilds and he can put in any parts either fine used or new into your engine. Who are you to argue as he is the specialist. The ball is in his court because whatever he says about the engine he has rebuilt for you, he is right in every way, including the bill. Why do people become specialists? Well in my opinion it is the only engine they know how to build or they are catering for a captive market. If it is the only engine they know how to build then they have a very limited ability and are incapable of venturing out of their skill base. If it is for a captive market, it can only be for money.  We all have to earn money and make a profit, but think, the specialist is usually a limited supplier of new parts. He often does not produce the parts himself and will mark up parts by 100% that he has bought in.

The thoroughbred engine restorer has studied engines, how they work and if need be how to tune them to get maximum performance or to their customers specification. He can work on any engine, they are all basically the same, but if he gets stumped can always look it up in a manual, on the web or can use his skills that he has acquired through books and technical college to resolve the problem.

If one is to specialise in one particular engine he will have a very limited amount of tooling. The tooling will comprise of all the factory kit and maybe some special tools that have been made to the builders requirements. He will have a basic fly press for pressing bearings and bushes in & out of cases. He may have an oxy-acetylene torch for heating up cases and welding up broken pieces of frames. A lathe, albeit a small one, probably a bit bigger than a model makers to turn up bushes and guides. This is what is needed bey the specialist, but what happens when he needs a barrel relining to standard, re-boring and honing. Where is he going to send the crankshaft that needs about 30 tons per square inch to push the big end pin; to the crankshaft specialist. What happens when he needs a two stroke cylinder liner replacing on a high performance racer and the ports have to be replicated to the standard tuned opening times, you guessed it; the specialist in this field. All the specialist input racks up the bill to the customer.

• Case study No.1 (stories from our customers)

A customer gave a petrol tank to a classic motorcycle restorer for restoration. He sent it out to a specialist tank restorer. They did all the work of lead filling, chrome plating, painting and lining the tank. Six weeks later the tank was given back to the customer with 100% cost and VAT added. The customer was happy with the job , but ignorant of the real cost. Moral of the story is if the customer had spent a little time looking for the specialist tank restorer he would have paid alot less for the same job. Looking on the web, classic motorcycle magazines or word of mouth are starting places. Obviously asking if it was going to be done in house is also a good idea.

• Case study No.2 (stories from our customers)

A customer takes his Norton Commando to a motorcycle restorer. He tells him there is a slight misfire at high revs. Restorer say he will look into it. He returns to collect the bike and is give a bill for £427.53.  Hells bells!!! for a misfire. New parts are coils, Boyer ignition system, HT leads and plug caps. Twelve and half hours labour?

It amazing what some restorers will charge

Unfortunately not taking the hint after the first bill the customer goes back to a motorcycle restorer because it is running poorly again. He tells the restorer it does not seem to run smoothly and the electric start seems noisy. Restorer says no problem I will sort it out. He returns to collect the bike and is handed the bill for £490.48. New parts spark plugs, needle jet, main jet and sprag clutch. This time 14 hours labour! Smacks of someone just bolting new parts on until the problem goes away and how often to replace a needle jet on a Mikuni carb!

An oceanic bill? YES!!!

Finding the right people

Lets look at the engine. If you could find a workshop that does precision engineering with a mechanical background as well you would probably find they have made parts such as percision crankshaft parts and have fitted special sized plain bearings into crankcases. Basically what I’m saying is you don’t need to go to the one mark specialist. If you have a classic bike and it in need of a full restoration, do what is most cost effective; find the tank restorer, find the cylinder refurbisher, find the frame striaghtener & weld repair specialist, find the cylinder head restoration company, look on the web and search for that aluminium welder to repair your crankcases, download information on local seat restorers.

You may be lucky enough to discover a local company that will do most of these things, including wire wheel building and classic bike electrics. If you do find one you will be quids in on your restoration project, because a company that genuinely say what it can do in house is going to get enough work from your restoration project at a reasonable profit and will not be afraid to divulge what they cannot do. They may also point you in the right direction or recommend a specialist in crank grinding or local paint sprayers for example. After all classic motorcycle restorers all know each other in one way or another and know of the specialists who carry out the work that we cannot do or do not have the knowledge or specific machinery to do.

When you approach a classic cylinder head restorer you will evidently see the associated machinery to do the job. He would be pleased to show you how the machinery works and some work in progess or completed. He should be happy to do so, as you are a prospective customer and he make a living from you, so your experience will generate more work for him by you telling others how good he is. When you walk  into a motorcycle seat restorers workshop you will expect to see vinyl’s,leather cloths and industrial sewing machines throughout. But if you walk into a classic motorcycle restorers workshop I bet you will not see a chrome plating shop, a person building wire wheels and someone on a lathe making crankshaft parts. All these specialist fields are undertaken not by the classic restoration company, but by specialist is their respective fields and this will cost you as the classic bike restorer marks the stuff up as the middleman.

The restorer who says he perform complete restorations is talking a load of bull. He would be a lair as we would if we said Stotfold Engineering can cast you a new crankcase, but we know someone who can and would be happy to point you in that direction as long as you gave us the opportunity to quote on the machining of it.

As I said previously if you can find a company that can carry out most of your requirements in house you are lucky. We at Stotfold Engineering consider ourselves to be one of those restorers luckily. We sub very little out in respect of the restoration and refurbishment of classic or custom motorcycle and cars. Are costs are generally lower than the specialists. We don’t have shinny polished floors, advertising memorabilia, boxes of brand new ‘Snap On’ tools, customer coffee machine (although if you ask we might make you a cup of tea) and immaculate boiler suits, because we don’t believe in the bull**** baffles brains concept. We get on with the job as true enthusiasts. As you can see some our machinery is not what the average restorer would have.

Things to watch out for before you sign up with a classic motorcycle restorer.

1. Is the company a one man band? – One person cannot do all aspects of the work and will therefore sub work out and cost you dearly. You will pay for the specialists he knows and uses.
2. When you walk through the door are you made to feel welcome? -  Someone who immediately welcomes you and shows interest in the work you want doing wants your custom. He doesn’t keep you waiting while he’s on the phone in the office chasing up subbed out work.
3. Is the proprietor happy to show you the machinery they produces the work on? – If they use excuses like ‘that aspect is done at our other workshop’ or ‘health and safety does not allow you to enter’, beware!!
4. Are there lot of bikes on the premises under construction?- Motorcycle restoration takes a lot of time to finish a bike off and get it off the bench. If you have been getting parts of your project restored by the same restoration company keep an eye on how other customers bikes are progressing and don’t feel out of place asking about them. He may say it is for himself or a long term project. Colin, here at the workshop has a few bikes of his own he works on, as do I. However there is a company I know who has had customers bikes on the workbench for a number of years. The customer of the bike could not afford the astronomical bill and as no quotes were given for the restoration was unable to pay.
5. Is the propreiter happy to divulge specialist suppliers in his initial quote? – If they are cagey about this, then they are planning to be the middleman and this will be costly for you. Do a web search and look around for specialists. The honest company will know you may check the price with the specialist supplier and it will unlikely to rip you off. Bare in mind however that quote over the phone and without the specialist seeing them can be considerably different. You cannot quote on something you cannot see the condition of. Some suppliers will give you a very cheap quote just to get you in the door and then add addition costs to bump up the price.
6. Are they willing to give you a rough cost estimate on the refurbishment of a particular part or the re-manufacture of that part? – If you don’t get a rough quote, listen to their patter. “It won’t cost too much” or  ”it won’t take long to do” are really not much use. Ask them to give you a quote for the most it will cost.
7. Do they give the old parts back? – A good restorer will be open and honest with you. He will hand you back all the old parts he has removed to show what he has replaced and show its condition.

Full restorations are very hard to quote on. It is often the case that until a bike is completely stripped that you know the extent of the work that needs doing. A restorer will not a quote for the whole job as there are too many variables in what he cannot see. He is unlikely to quote you a huge price, which would put you off using him, but may have a flat rate for the basic engine strip and build without parts and specialist repairs, which will be extra. If you supply your bike broken down for inspection supplying notes on what you think needs repair he should be able to give you a fairly accurate quote. If he cannot quote on say a crankshaft repair then he will be subbing it out at your expense.

Another pit fall to watch out for is the restorers hourly rate. These mean nothing to the restorer as he can model his final bill to justify his rates. He says his hourly rate is £15.00 and you say that’s cheap, do the job. The only problem is he gives you the bill for £150 and says it took 10 hours to adjust the carburettor. As shown earlier in case study no.2, the so called restorers of classic motorcycles are only to willing to make up for their lack of business to rip you off. Remember it is very hard for a classic motorcycle restoration business to survive on restorations of bikes alone. There just isn’t enough work to go around, so those that do will want to make the most money from you.

I hope you find what Colin and myself have said to be use in enlightening you on the practices of classic bike restorers. Stotfold Engineering is lucky enough not to rely solely on bike restorations, even though it is our passion. Our versatility allows us to carry out a multitude of different services not only on classic motorcycles. I hope one day you will test our services and would be pleased to be put to the test on the seven points I raised earlier.

Stotfold Engineering looks forward to the comments aroused by this publication from the professional classic bike restoration faternity and prospective customer alike.

By Terry Ives with input from Colin Jones

Triumph Tiger 100 crankshaft & con-rods

I have inherited from my father, Terry Ives, a 1954 Triumph Tiger 100, the first of the swinging arm models. The crankshaft and rods had gone missing some years ago, as they do, so I endeavoured to source a replacement.

The original one would have been what they called a one piece crank, but I knew the crank from this particular Tiger was swapped for a three piece one. The previous owner used it for sprinting in the seventies. The one piece cranks were a lot tougher under extreme loads. I looked on Ebay and found a crank for sale in Chile, South America. I purchased it and found it had very large big end journals, but according to my Triumph manual this was the right size. The whole of the crank was very grotty and had had modifications done to it to keep it running through the years, so I looked for a second one. I managed to pick up another Tiger crank, and this one came with rods, which I also needed.

The con-rods had white metaled steel caps and the rods themselves were made from duraluminium. The big end journals were a lot smaller and the crank was stamped 6T. The stroke was 82mm as was the Tiger 100. I measured the big ends of the rods and found they were worn out of tolerance. I asked several companies about reconditioning them on the off change that there were other engineering companies who had experience with salvaging con-rods, but nobody could help me. I fact several companies said it could not be done.

Have owned and run Stotfold Engineering for the past 40 odd years I thought I would put my restoration skills to the test and solve the worn out con-rod dilemma, and besides, nobody says it can’t be done to me. I machined the steel cap and the dualumimiun con-rod down by .015″ which caused the eye of the rod to be elliptical. I then secured the cap onto the rod with the correct torque settings to the stretch bolts. The con rod was then turned on the lathe to within .002″ under-size and then finish honed to restore the correct running clearances. The thickness of white metal on the cap was ample enough to have it machined out and leave plenty for years of service.

I was told in the past that if you have one of these type of con-rod , you should throw it away and get a new one. It seemed like a waste of a perfectly usable con rod and it has always been the policy here at Stotfold Engineering to repair, recondition or restore an item rather than just bin it. Our motorcycle repair and restoration workshop always look at the problems from this perspective to overcome engineering problems, not give other companies standard response of “you need to buy a new mate”.

by Terry Ives