Cyclekartist

This last week was fruitful, as I finally found some other parts I desperately need for the 250 engine. A type 74 Amal carb (NOS!) and a 4A float chamber are separately underway to here…

… Along with a single-port head for the beast, in case the setup as bought doesn’t work as I want it to.

I also have an original rocker assembly I acquired recently sitting here, too 🙂

Unfortunately, the innards are scrap and the front cover had been badly welded, bodged with filler and then sprayed silver to disguise the damage.

Needs a bit of fettling, but otherwise good 🙂

Since the ‘Posty-Bike’ Honda C90 hubs are almost non-existent this side of the pond, I decided to make a move today and get me some Simson S51 hubs to get me started. Picked up all four, nicely bead blasted and ready to fit out for a princely €47 including Postage! Now all I have to do is to sort out spindle-size, bearings (I want to use Timken taper-rollers if possible) and also sort out which rims and tyres I want to fit. Mulling using 185 x 17s for the rims with 3.0″/80mm tyres with an appropriate tread (nothing too modern, nothing too knobbly!)

Already decided upon is a straight tubular front axle, underslung transverse leaf and ‘dampers’ and long track-rods in a ‘V’ mounted well back to the chassis to avoid the ‘anti-roll-bar’ effect and resultant understeer associated with this setup. Will have to design and have cast (to my patterns) all the bits and pieces apart from the tubes. Let’s see how that goes!

This is sort of the look I am aiming at (apart from the track-rods shown here):

These are the hubs that I bought for €10 each!

Already bead blasted for my pleasure! They will eventually be, with the spokes and rim, all ‘painted’ black. What I have also done is to cut some disks to weld in, so that they are stronger and look ‘cleaner’, as below:

I’m still not sure that I won’t reduce the length of the long spigot in pictures 1 and 4 to enable the king-pin etc. to wander a little inside the hub, so that I don’t need to design in quite so much camber to make the steering lighter… I aim with the steering setup at neutral characteristics, leading to light oversteer if pushed hard. All a question of balance – not to mention trying out in anger!

Still looking to fit Timken taper rollers if I can find a set with the right dimensions…

I am at the testing stage with the chassis construction. I have access to bending and laser-cutting and TIG welding equipment at work, so I shall take full advantage of that, especially as I can use all of those myself. The chassis rails are about 1200mm long and I want to weld up box sections, the outside folded around and a strip welded down the centre with lightening holes along the length. Since welding considerably distorts long sections, I am starting with a box-section of around 60mm x 40mm, 1.5mm thick. The actual measurements are a little different due to limitations when bending on our machine (size of Matriz and safety margin), so I have to change the bends for the next test!

Anyhow, this is generally how I originally intended t0 go on: WRONG!

After aligning and welding freehand the full length on both sides, some evidence of incorrect welding settings are visible here. Too much heat for a start at some points, which I could have avoided – but that is what a test is for! Material is stainless, by the way. I should have only welded in the solid areas, avoiding the thinner areas around the holes. That would have helped with minimising bending inwards and only affect the strength very little. As a result, the thinner areas are burned out and look ugly.

Look at the amount of bend on this short length (380mm). The chassis members will be four times as long, making the distortion 16mm from straight. I could, of course weld two strips the length of the other side to equalise the shrinkage, but that would not satisfy my idea of æsthetics for the job. That is not what I’m aiming at!

What a mess!

The plan now is to bend up two square C-Sections and weld them top and bottom the whole length, which will also avoid welding close to thin sections next to the holes. That should remove the bending problem and give a reasonable rigidity (despite the lightening holes on the INSIDE) and ‘look’ to the whole thing. The chassis will be powder coated gloss black, I think, so it really won’t matter that much as for a good length of the chassis, it is covered by the bodywork anyway.

And, of course, I will be using a decent steel instead of bendy stainless!

A Cyclekartist is what anyone becomes who even attempts to build a cyclekart!

At the moment this site and the kart I intend to build (an Austin7 ‘tincan’ – twincam! – replica) are in their infancy. Please give me a few weeks – or years! –  to get things on the move. Ahead of the site proper, I can say that it will appear as a blog with separate blogs for each stage and will start off with some documentation, a spec-sheet, my shopping-list, some pictures and drawings as I progress to and then through the actual build. I hope you enjoy the process and occasional discussions you will find here. Peter for Armstrong, to whom this build and site are dedicated to and who will join in later, when the time is ripe (which HE will decide!).

The picture above is the look that we are aiming at – still a lot of work to get the drawings right and then an attempt at some 3D drawings to get the project sorted and tried out. THEN comes CAD (Card Aided Design) to finally sort the bodywork and final fitting out!

Wheels are still a problem inasmuch as I have not yet decided which hubs and rims to use. The front axle is the main conundrum at the moment, so I will be updating on that as time goes on. Still looking for a reasonable program (sorry, ‘App’) that will simulate the movement of  linked chains of moving parts efficiently, easily and cheaply!

The aim is to build and design everything myself with a minimum of bought-in parts, so plenty of things to figure out and try out, too! No idea where I’ll be able to do the latter, but time will tell…

Above is the badge that will adorn the top of the ‘radiator’ cowling on the Austin7 ‘tincan’ Special

And below the drawings of the original idea of which one to build… That has changed a bit, but nice drawings and so I include them here. I’m working on a new set for the new bodywork, which is higher at the front to better accommodate the height of the JAP 250cc OHV engine, since it is a lot higher than the side-vave 200 that was originally envisaged.

Whatever is ‘laid down as law’ in the various countries, clubs and groups, a cyclekart is first of all a fun machine. So, whatever ‘regulations’ apply, the primary intention is to have fun – building it yourself and then running it (and of course showing it off!). There are, of course, ‘guidelines’ in place to set a framework of how and what to build and to set out where the limits in size etc. lie, but these are well intended not as limits to your creativity, but to stop advantage being taken by the unscrupulous, which , let’s face it, spoils everyone’s fun.

Definitions decide whether a vehicle is a motorcycle or a motorcar, for example and no one is going to argue a car into a motorcycle and vice-versa. The dividing lines there are self explanatory unless you happen to work at the tax-office, of course!

Sooooo, what actually IS a cyclekart and what sets it apart from other vehicles?