THE "WHITE ONE"

Well that’s what most people including myself refer to it as and until the addition of a big blue bottle on the side of it most people didn’t really understand what the bike was really all about. In fact when I started building it 3 years ago neither did I! But suffice to say it is now the hardest and the last special I will be building for some time to come.

In short its a 500cc H1f engine, in a 72 S2 350 frame. The engine is converted to water cooling but retains the original air cooling fins, a belt driven supercharger (As opposed to an exhaust gas driven Turbo Charger) is bolted to the back of the engine and a single 55mm throttle body with two injectors plugged into a digitally mapped microprocessor is mounted on the inlet side (this is the replacement for a carburettor), and for a bit of amusement a spare nitrous kit I had on the shelf was also bolted on . There are many, many other minor modifications to the motor, frame and accessories which I will now attempt (without the use of a safety net ) to list in no specific order.

Alloy front rim with Stainless Steel spokes laced into original four leading shoe H1R racing drum (there are those that have called me a criminal for using a genuine works H1R front hub J), forks are Kawasaki KR1S with the front disc mounts machined off and lugs welded on to mount the stays for the drum, yokes are KR1S with the centre pivot replaced with a S2 item, the top yoke has been welded up to take a boost gauge for the supercharger and a ammeter, the rev counter is standard H1 or 2 but the Speedo has had the internals cut out and a digital unit from a very fast bicycle installed, steering bearings are tapered. The tank has been altered to take a aero type fuel cap and has a much chopped about fuel tap that only acts as a connector (a bonus here - you don’t need to turn the fuel off with injection you just turn the pump off). The rear wheel is again a alloy rim with Stainless Steel spokes and the hub is standard H1 but the brakes are actuated hydraulically via the use of a car slave cylinder and modern bike master cylinder. Sprocket is alloy and the chain is "O" ring. The swinging arm is again KR1S and of course is a monoshock. Rearsets come via Harris.

The wiring loom is home made with good quality connectors (all soldered ). As mentioned above the barrels and heads have a full water jacket which is pumped around the frame and through a radiator ( actually a large oil cooler ) by a KR1S water pump welded into the what was the housing for the distributor ( the clutch cover is off a early H1 ). The supercharger is supplied by a Mr Faegol in America and is connected to the inlet ports by a home made manifold of 6mm alloy, this connects to 38 mm rubber inlet stubs I believe off a Yamaha . The inlet manifold is again 6mm alloy and bolted to this is a 55mm throttle body exactly the same as used on the British Touring Cars. Plugged into this are two Bosch injectors and in turn these are plugged into a microprocessor, this in turn takes information from a water temp sensor, an air temp sensor, a throttle position sensor and the ignition sensor and compares all this information to a pre prepared "map" in its memory and on this basis determines how long the injectors stay open for (confused yet ?) In other words, how much fuel the engine needs for optimum performance.

The air is drawn in via a 7 inch by 4 inch K&N filter. The fuel pump is electric and controlled by "big brother" and pulls fuel from the tank and sends it off to the injectors at about 50 psi created by a pressure regulator which returns any spare fuel to the tank. The ignition pick up is Triumph (triple) and there are 3 ignition units each of which looks just like the single unit on my 6 cylinder Jag. With all these electrical bits the standard alternator was not up to the job. So, that was sent off to the spares bin and replaced with a gear to power a toothed belt which drives the supercharger at about 150% engine speed, and then on to a alternator off a modern superbike (source unknown but most likely Yamaha), tension is maintained via a idler pulley. These are all enclosed in a aluminium cover. The battery is a high spec sealed unit sitting in a home made holder, again 6mm alloy.

That covers most of the mods’ apart from a volt meter which slots neatly into to the oil filler cap hole of the side panel, the expansion chambers are off a old drag bike , finished with carbon fibre F1 cans, the expansion vessel is in the rear seat hump (which also incorporates a safety valve). The ignition coils are Dyna, the clip-ons are from HARRIS, the fuel rail is a home made item, and the headlamp brackets came from M&P, oh and of course there is the Nitrous.

When I had the bike first running there was considerable doubt that the fuel injection would be ready in time and I wanted to see if the thing would simply run. So, I took a 36 mm H1R carb off my sprint bike and stuck on the back of the supercharger. Using my own dyno the first results were not good i.e. 19 hp at the back wheel !(time to start worrying) Fiddling with the jetting got this up to about 31hp and increasing the speed of the supercharger which originally was running at engine speed got this up to 39hp, again not great, but Didn’t know if the jetting was correct and when I pulled the engine apart to clean it all I found the left crank seal had come out ( seems the blower was working OK). The ignition also needed to be played with. So, all in all 39 hp for a first set of runs was not too bad. Closer inspection of the barrels also revealed that the exhaust ports were not at the same heights (now all raised to match ) and I hadn’t yet opened up the inlet ports to match the inlet rubbers ( now done). I also remembered that fearing over compression I installed two base gaskets (one now removed) so all in all, when the jetting - sorry, fuelling is set up properly theory should dictate over 70 hp at the back wheel (without the Nos ) we will soon see.

Well the big question of course is "how fast does it go mister ?" well I don’t know! And I’m not too bothered either. The real fun for me is getting the thing to work and indeed it does but what you have to remember is that any project of this nature takes a lot of development and that in essence the "fine tuning" is the next project. The fuel injection was literally thrown on the bike a few days before the rally and many hours of time on the dyno are needed to set the fuelling up properly (the current map is just a rough guess). Just to get the bike to run is complicated enough, the road to perfection will be a long one, the usual sequence of events is: …….Put the bike on the dyno, plug the microprocessor on the bike via a "dongle" into a laptop PC, put a gas (hot wire) analyser in one of the pipes run the bike and check the mixture reading at a given engine speed and throttle opening, plugged into the laptop is also a box with two controls one for ignition advance/retard and one to vary the mixture, you then twiddle with both of these to get the right reading on the "gasometer" and enter the correct figure into the laptop which will in turn "log" this into the microprocessor as a permanent reference point on the fuel Map. Now if you then consider that this fuel map has 32 different rpm settings by 16 throttle positions you then have in theory have to do the above 512 times! which is what I meant by hours and hours. In reality I think (and hope ) that an experienced tuner doesn’t need to look at each point and should get a general feel for the way the curve needs to go by looking at some relevant points.

Now most people can figure out how most of the bike works but cant understand how to "watercool" a air cooled engine, simple really. All manufacturers (back in the sixties ) used to leave a lot of "tolerance" in their products and if you look at the heads of any two stroke you will see there is a lot of metal in them (especially if you have a band saw and cut one in half) i.e. almost an inch at its thickest point, this then allows you to machine most of this out to form the water way and then a plate can be welded back in which then forms the new face of the head. Add a inlet pipe at the top to the rear and some outlets at the front which open into the jacket of the barrel and there you go . The barrels have about a 12mm wall of ally around the cast iron liner and it is this which you remove to form the waterway, the only tight point being around the head bolts , add a outlet point at the back of the barrel, connect this up via a header (as the heads are) and the rest is basic plumbing ( apart from the fact that the heads leaked as I had removed most of the gasket surface) These major leaks were solved by using diesel engine head seals specially made to size and other minor leaks were solve using Holts " cylinder block crack repair"

There are still many problems to solve i.e. the possible need for a boost wastegate, a front brake that doesn’t and a good possibility of overheating not too mention the fact that some goon wont insure the bike for road use! But hopefully by the next rally the bike should be on the road.

Simon