Well, here we go. The Impulse saga started for me some 15 - 20 years ago when I was round at my mate Paul's place in east London. "come out ere' and catch a load of this" said Paul.
I was taken to the garage where amongst other 2 & 3 wheeled contraptions lurked a fairly rusty beastie known as Impulse.
It was built in 1966 by Mickie Pierce who built bike frames for a living (more of him later) and ridden by Vic Phillips.
It did the rounds including the Brighton Speed Trials and various sprint events and also competed in the 1966 Elvington records meeting.
Vic & Mickie also built Impetus. A road race bike with a carburetted Imp sport engine. This was seen by someone at the Rootes Group who subsequently sponsored the bikes and provided a works 998 sport engine for Impulse.
Back to this January. Paul called me to say that he would succumb to the pressure I had applied over the last 2 decades and would I rebuild Impulse with a view to running it at Brighton once more. Game on said I
.
I went over to Paul's place with Mr oily bike and a trailer and picked up what can only be described as a bloody mess. The rolling chassis was complete ish but the old girl had suffered a flood, a leaking shed which filled the blower up and a fire which smoke damaged it.
A full strip ensued and the fuel tank (frame top tube) was drained of 20 year old fuel and water emulsion which had left so much crud in the tank even hot triclorethelene struggled to remove it.
Tank cleaned out as best I could I then pressure tested the tank. A small leak at the back and a gusher at the front where the fairing bracket had been bent. I decided that the only way to go would be to have the frame blasted so I could see what was going on with the tank and the rest of the joints. Got it back a few weeks later to be surprised by the lack of damage. One lightly cracked joint and the two fuel leaks brazed up then the frame went to powder coat. It only has a light dust of powder so any frame joint cracks can be detected before they become disastrous.
The rest of the chassis came next, 3 wheel rims and hubs dismantled and polished. New spokes and bearings. Plated fasteners and rebuilt. I did all the work except for the polishing. I hate polishing because of the mess it makes of the workshop,
Fork stanchions hard chromed and plated. Fork legs and bottom yoke powder coated. New bushes made and as the head races were obsolete, 'near enough' metric taper roller bearings sourced and thin wall bushes made to accommodate them. Brake shoes relined and hey presto a front end. I moved on to the transmission. The AMC/Norton gearbox was completely refurbished. All bushes and bearing fitted. The gears were surprisingly good. There is an extention piece between the gearbox and the clutch to get it in line with the engine flywheel which has been turned down for lightness and adapted to take a Norton crank sprocket. This was missing as was the adapter plate to mount the sprocket. This was remade and a Jawa speedway sprocket was used as many sizes are available if gearing changes are needed and are the right chain size. The tranny extention is a home made item and carries a double row bearing in a special carrier to support the now, very long output shaft. This was re-furbed and plated.
On to the motor. Took the bottom off to find the crank in perfect nick. It is truly a work of art. Hand polished and tufrided. Has an unusual bluey purple colour. Rods, pistons, bearings oil pump etc found to be in good nick too. So far so good. On to the head. These heads run Wills rings. They replace the head gasket. They are hollow steel rings filled with nitrogen under pressure and sit in a recess machined in the head and bear on the liners and are designed to cope with the high pressures generated in a blown engine. The head was shagged sadly but Paul being Paul had a spare. New Wills rings sourced together with the special water jacket gasket the head was on.
These motors have under bucket shims and I had real problems shimming it until we found that the buckets had worn barrel shaped and were rocking causing variable clearances. This was due to the mildly radical cam sweeping the buckets sideways whilst attempting to open the valves. This sorted the top was on. Engine fitted and the rest of the cycle parts re-furbed and in place the old bus was taking shape. Next was the blower and the SU carb. Easy enough. strip & rebuilt. New bearings and trunnions for the blower and a new needle and a rebuild for the carb. Job done. Sounds easy but this all took nearly 7 months and 350+ hours to do plus countless journeys sourcing parts and advice.
Cooling system re-furbed and a neat electric pump from the states fitted all that was left to do was the ignition system. Paul decided that the Scintilla Vertex magneto was the way to go. I bench tested it and it sparked. Sourced a new cap for it. Made up some leads, timed her up to 32 degrees and we have ourselves a bike. Woo hoo!!!.
Paul arranged for the paint on the fairing and the chair as this is not my forte. And a really nice job too.
In the next installment I will relay its first fire up and its maiden voyage at the festival.
Pictures below.............