Phase 6

( Click on images for more detail )

 

 

Twin Turbo Jet Cycle

 

Preliminary 3D mock-ups of the JetCycle. I originally intended to put my jet engine into an ordinary bicycle for lightness, but when searching the net I came across the sport of Mini Moto racing ( 50cc mini race replicas and dirt bikes ) and consequently a whole source of small, cheap lightweight cycle parts! 

 

 

Twin Turbo Jet Cycle 2

 

Improved versions of the JetCycle model including chain, sprocket and freepower. Work still in progress.

 

Mini Moto Dirt Bike

Examples of Mini Moto's. Jet Cycle front end based on the Mini Moto dirt bike frame and forks using wheel from the race version.

 

Frame and Forks

 

Mini Moto dirt bike frame. Frame and forks came as a package, bought through Ebay. The frame may or may not be usable depending on how the design of the rest of the bike pans out.

 

Forks

 

Mini Moto dirt bike front forks. The forks from the race versions don't have any suspension. These units will come in handy!

 

 

Front Wheel

 

Mini Moto front wheel and race slick. This wheel does not normally fit the dirt bike forks, so they are a bit of a squeeze, but looks cooler than the larger skinnier dirt bike front wheel! ;o)

 

 

Yamaha TRX 850

 

The donor bike for the rear end of the Jet Cycle. The rear wheel, swingarm and rear brake caliper had to be from the same bike to ensure that I could fit the parts together without modification.

 

 

Rear Wheel

 

Yamaha TRX 850 rear wheel. I wanted something with a wide rim and tyre and just happened across this on Ebay. Fits the bill nicely!

 

Swingarm

 

Yamaha TRX 850 aluminium swingarm. Ebay again!

 

Rear Brake Caliper

 

TRX 850 rear brake caliper, cheap and in good condition from Ebay

 

Rear Brake Cylinder

 

Rear master brake cylinder from a Suzuki GSXR1000 in excellent condition from Ebay. It didn't really matter which cylinder I used as long as it was from a bike of similar size.

 

Mono-Shock

 

Rear shock from a Suzuki SV650. I had difficulty obtaining a shock from a TRX850 so decided to go with this one which fits perfectly. Again, bought cheaply through Ebay in very good condition.

 

Jet Cycle

 

Rough layout of the Jet Cycle. The finished oil/fuel system can be seen on the ground to the left. This will eventually be mounted above the shock between the rear wheel and fuel tank.

 

Rear Suspension

Suspension Animation

 

The shock absorber can be seen poking through the swingarm ready to be mounted. The bottom of the shock will be attached to the rising linkage which will be pivoted to the tank. The shock top mount will be similarly pivoted to the top of the tank The 3D images show how it will eventually connect together. Click on the above link for an animation showing the suspension in operation.

 

Rear Brake Unit

 

I made the mounting brackets for the rear brake cylinder from 3mm steel sheet. It will eventually be cable operated via a lever on the handlebars. The cylinder and oil reservoir is mounted as a single unit in a neat package. There were ready made 6mm holes tapped in the top of the swingarm so this determined the original mounting position.

This unit will now be changed to the other side of the swingarm for reasons as explained below.  

 

 

 

 

 

Sprocket

91 tooth kart sprocket, chain and pinion, ratio about 10:1 providing gearing for about 70mph. Sprocket mounted on original cush drive. I needed to use kart sprockets to achieve the desired reduction. Wide choice of sprocket ratios available so easy to change gearing.

The wheel has been reversed for freepower use so that the sprocket is on the correct side side to allow the freepower to drive the wheel in the right direction.

 

Brake

Rear brake also swapped over resulting in a top mounting arrangement which I think looks better! ;o) Luckily the original chain guard mounting lugs on the swingarm line up well with the caliper 'stay'  which I will use for securing. The brake cylinder will also be re-mounted on this side.

 

Levers

 

A couple of bicycle brake levers found in a scrapyard for a pound! ;o)

 

 

Fuel Tank

 

Fuel tank made from a large butane cylinder ( found dumped near my house, lucky! ). The tank will form the centre of the bike which is strong enough to act as a stressed member from which all parts will be attached, so no need for a frame. There should be enough capacity for at least 5.5 gallons of Diesel. Swingarm mounting brackets made from 8mm steel plate needing to be welded to the tank. The seat will be mounted on top of the tank.

 

Fuel Tank 2

 

Swinarm brackets welded on and also the 3 mounting brackets for bolting the front end frame onto. Having everything bolted to the tank means that the whole machine can be disassembled into 3 main parts for easy transport in the boot of a car.

 

 

Fuel Filler Cap

 

I wanted a low profile aircraft style filler cap so that the seat can be mounted on top. I found one on ebay..

 

Jet Cycle 2

Finally got round to making some stands and start to position things a bit better. The stand for the rear wheel was made from the forks from a bicycle with some paddock stand 'hooks' welded on. The rear brake caliper is now in position, with the 'stay' ( which had to be shortened ) fixed to a bar that bridges the original chain guard mounting points. Hopefully this arrangement will be strong enough to withstand the pressure..! ;o)

 

Jet Cycle 3

Here the fuel tank has been elevated using a couple of axle stands and provides the perfect height in relation to the rear wheel so that the angle of the swingarm is correct.

 

Jet Cycle 4

Now that the swingarm is correctly angled at the resting position, I can begin decide on the positioning of the mounting points for the suspension linkages. The mounting lugs will be made from the same 8mm steel plate as the swingarm lugs are made from.

 

Here are some sample 180 degree pipe bends obtainable through ebay. I will be chopping them up and using them to build my own rear frame from scratch.

 

Chain Tensioner

Originally I was to mount the engine and freepower unit on the swingarm. After careful consideration I decided to mount the engine and freepower unit on the frame itself, the swingarm moving indendently of the frame/engine/freepower. This created another problem in that the chain final drive had to have some mechanism to take up the slack as the distance from the rear sprocket and freepower drive sprocket would be constantly changing. I was going to make up my own chain tensioner but hit upon the idea of using a bicycle rear derailleur. I removed the original sprockets and replaced them with modified Rotax kart engine sprockets which are practically the same size and running on ball races. The bearings were a fraction of a millimeter smaller than the inner diameter of the sprockets so a bit of Loctite 638 retaining compound was used. Job done..! ;o)

   

 

 

Last updated

Sunday, 10 August 2008