May 2004

So what was left to do now?

Fit the exhausts
Fit the engine frame to the floor
Fit the starter cup
Wire up the CDI
Make a throttle control cable
Fit the fuel system components - and a seat/cover
Forget the power valve controller for the moment - I can always do that later.
Fit the skirt
Fire up the engine
Hope for the best!

Hmm... not very different to last month :-(

Although it seemed that it was almost finished, there always seemed to be a few more things to do, and the end was always "just around the corner". So I decided that I would need to take a week off work and really crack on with the hovercraft.

The starter cup

As most of the contents of the engine/gearbox case had been stripped, the kick start no longer worked so I needed to fit a starter cup for a pull start - as used on small lawn mowers the world over. 

As this is going to be spinning at 10,000 rpm it had to be made accurately so that it was balanced. In particular the fixing holes needed to be equally spaced on their PCD. I had bought one from K&M and this looked well made, but it also looked like it needed fixing to a sloping surface on the flywheel,  and drilling an accurate hole onto a sloping surface sounded tricky. I needed someone who knew more than a thing or two about drills and stuff. Ron in work came to the rescue and turned up a new starter cup on the lathe that allowed it to be fitted to the flat portion of the flywheel. The three mounting holes were drilled using a dividing head - an old but essential bit of kit. I then screwed the starter cup to the flywheel using a few drops of "studlock" to hold it in place. 



Having the wiring looms and instruments from two bikes I decided to sort them out.


The wiring on the hovercraft needed to be radically different to what was on the bike. Most of it would be thrown away, and what I did use would need to be cut or extended to a different length.

I decided to mount the rev counter and temperature gauge in a pod over the bow, and put most of the electrics - the CDI and PV controller in a box near the engine. Hopefully I could use as much of the original wiring as possible - that way I would have the right wire colours, which is always a help when trying to fault-find. Vehicle Wiring Products supplied the spade connectors and some multi terminal blocks.

Using some 1.5mm sheet aluminium, I cut out an instrument panel to hold the rev counter and added a length of half inch aluminium angle around the edge to attach it to the cover. This was a semicircle(ish) which I folded the edge over to stiffen it up. I added a couple of brackets so that I could screw the pod onto the (thick) T-section which supported the bow deck.

Hull panels again

Things were going OK when suddenly I dropped my bench vice onto the deck - DOH! It didn't cause too much damage but it did leave a couple of nasty dents, each the size of a postage stamp, and it sort-of lifted the edges of the deck slightly between the screws. This made me think that if the hull got hit in the middle of a panel it might leak around the edge. I decided I needed to reduce teh distance between the M6 screws, so a lot of drilling and thread tapping followed.

And how was I going to seal the edges anyway - some sort of silicon sealant or mastic I suppose. I bought a tube of Sikaflex and tried to join two pieces of bare (shiny) aluminium. Wow! Messy stuff - but boy does it provide a tough seal.

More on the bracing struts
bracing strut bracket . The bracing struts join the fan frame to the hull frame around the cockpit, passing through the fan frame on the way.  To make it easier to attach the lower end of each strut to the hull frame I welded on a semi-cylindrical bracket which followed the shape of the frame tubing. I then screwed the bracket to the hull frame using M8 bolts.

Fan Guard?

With the struts in place I needed to rettach the fan guard and cut out a few links in the mesh so that the strut could pass through. Strangely, even though the fan guard is 1 metre diamater I couldn't find it anywhere in the garage. Where was it? The last time I remember seeing it was when I put it on top of the landrover for "temporary" safekeeping. Does that mean I drove off with it? Who knows, but I never found it again... Luckily Ken from K&M had a replacement - but what a waste of £50 !


The plan for the steering was to base it on bicycle-type brake cable and handlebars. So I built a steering box from 1.5mm sheet and half-inch angle, and used a bicycle steering stem and a simple handle bar. I fitted some bracketry to the bottom of the stem to fit the ends of the cable to. Cables run along the side of the hull, back to the rudders. The left cable pulls for a right-handed corner and the right cable pulls for a left handed corner.

Fuel Tank

petrol tank

The fuel tank is a plastic off-the-shelf  12Litre container from K&M. It's a little wide for the cockpit, but it should get me going. The tank needs to be covered by a strong seat so I built a box from 3mm sheet aluminium and hinged it at the front wheer it meets the floor. That way I can lift it up and forward to refill it, but the box will hold it firmly in place once I add a bit of foam padding inside.


Ideally the exhaust pipes need to lie over the rear deck, at the right side of the duct. The bend in the exhaust pipes that come with the TZR means that they need cutting and re-welding, but the simplest modification means they end up pointing upwards. This isn't great but at least it should get me going. I plan to eventually make a set of custom pipes, with some scrap stainless steel I rescued from our canteen kitchen refit. 

On the last weekend in May 2004 the Gang Warily race was held. I still wasn't ready, but the to-do list was getting smaller....

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