Pete's Billy-Cart Page NOW WITH AIR-COOLED POWER!!!

The cart in question is made almost entirely of scrounged parts. In fact the only parts bought to date have been, 3 inner tubes, 1 tyre, 2 crankshaft seals, 4 rose-joints, nuts and bolts, and some threaded rod. Not bad really. I figure I have spent at the most $80. The threaded bar was the most expensive bit at $18. The bike parts were collected post Christmas when all the kids threw out their old bikes after having got new ones from Santa. It was just a matter of waiting for council clean-up and then "cleaning up". The other bits of metal were left over from my buggy or just bits lying around. Even the seat was an old one from my buggy. The original plan was to put a 2 stroke mower engine on the cart. This hasn't quite happened yet, but if things go as well as thye did the other day, it should happen later this year. The motor is ready to go, we just can't get it to fire up yet.

I first posted this pic of the cart in January/Febuary (2005). As you can see it wasn't close to completion.


The front axle has plenty of castor and each front wheel has about 4 degrees of static negative camber built into it.

Throughout the year I have got little bits done but the cart wasn't ready for a full road test until the other day (27/9/05). As you can see, the chassis is significantly raked. This causes some ground clearance issues with the front axle, but we didn't manage to bottom it out at speed so it must be alright.


Here is the steering set-up. A number of people expressed concern with this setup, but on the road it is quite stable as the cart doesn't need to turn hard anyway.

Test Day

Here you can see our test hill. It was significantly steep. So much so that Joel swore he wasn't going first...Chicken! :P I started first and we worked our way futher and further up the hill. The street was ideal cause it went down the hill for a long way befor rounding a slight corner and going up hill allowing a good run off to slow down on. The street was also not too busy, however, Joel had to dodge one silly lady who backed out of a driveway and sat right in the middle of the road for half a minute when she saw him coming!
All in all the session was a success. The best part was having Brian's car to carry the cart back up the hill after each run. The top speed was measure at 50km/h while Brian was following me in the 'support car'. At this speed, my eyes were watering and my nose was running from the air rushing in my face. Top fun and the cart felt really stable too.


Brian in test mode, note the huge grin. ;o)


WARNING: Speed Thrills!!!


For the man who was chicken, Joel seemed to get over it fast enough. Less waving and more steering would be good at over 40km/h!

For all those worried parents, there is a brake. We have one caliper style bike brake on the back wheel. Initially, this didn't seem to work very well as the shoes were old and the rubber had gone hard. However, when they heated up under heavy braking they seemed to pull the cart up ok. Added to this, the back wheel has a pedal-brake hub. My plan with this is too hook up some chain, a cable and maybe a pedal at the front and use it for more pressing matters, or for sliding the tail end around too....:oD

For now, Brian is very keen to get the engine running and on the cart. It will no doubt make it even more fun than it already is. The down side to all this success, it that now I'm even more tempted to build a khanacross special for club racing on dirt. I already have some brakes, and engine, a bunch of tyres/wheels and 2 gearboxes. If I can just find some old tubing and a front end assembly, we'll be in business. :o)

9/10/05 Update...

As of yesterday we are in the middle of motorizing the cart. Brian came across a free 2 stroke that runs like a dream. The motor is all but installed with only the mounting of the fuel tank and a few other details to finish. The motor is dead standard the mo, however apparently it's not hard to make these things do 9000rpm or even 11,000rpm. Wouldn't last long with the latter though.

Expect pics and a report soon. ;o)

26/10/05 Update...

The cart has been out twice with it's new motor and seems to be lots of fun. Before I try and describe how it all works let me show you the pics of the setup.

As you can see, the output of the crank mounts directly onto the back wheel. The whole motor is mounted on a pivot just behind the backseat. The pressure on the tyre is in turn tensioned by a return spring from an old VW brake drum. You can start the motor one of two ways;

1. "Put ya back into it sunno, it's time for a pushstart"...this is hard work if the motor is cold (or if you've forgotten to turn the fuel tap on [blush]).
2. "Pull the ripcord"...we've left the original pull start on the motor. You just pull it a few times and off she goes. When it's warm you can pull start it on the ground with someone sitting in it.

What is worth mentioning is that it really needs two people to start it with any real safety. Brian made the mistake of stalling it at low revs the first day we took it out. "Easy," he though, "I'll just turn it down to SLOW, push start it and hop on." The result was hilarious. Turns out SLOW wasn't very SLOW at all and he was chasing it down the road with one hand on the handle bars and the other trying to turn it off. He ended up with it on it's side doing donuts. Funny to watch, but a bit of a worry. I almost made the same mistake today.

Anyway, the problem seems to be related to a sticky throttle. I had real issues getting it to stop to today. The other thing is that the back tyre is, or should I say was very old and hard. I say was because there's not much left of it now. In fact the engine has worn a hole right through it in two places to the point where the tube was poking out of one of the holes. It was at this point I decided that we needed to call it a day with no real brake, a sticky throttle, a soon to be puncture tyre and fading light.

As I mentioned earlier, this motor is quite under worked at the moment. It happily pushes it's own weight plus my 100kg bulk up a steep slope without any hassles so it's way under geared. Added to that it's only doing around 3500rpm in current trim and is good for about 9000rpm safely. Brian reckons we can get it to do that with no real internal mods and double the current power level. If that's the case it's gonna go SCARY!! fast. So expect some serious brake upgrades, and we might even fix the sticky throttle too. ;o)

Also of interest, we still have another 2 stroke sitting around waiting to be used. Brian's current idea is to put one on both sides of the back wheel. And before you ask...yes he is a mechanical crackpot. Personally, I think it would be awesome, if we set them up the right way it'd be horizontally opposed and air-cooled. :oD

6/12/05 Update...

Well now that exams are finished and I’ve had a bit of a break, I thought it was time to get back to the more important things…like the go-kart. The last time I rode it as you know we had significant difficulties with both the throttle and big lack of brakes. Accordingly, the brakes have got the most attention. Well, that and the back tyre, seeing the last one had some worrying lack of existence in a few spots. That is to say, one wacking great hole and another one well on the way. After bragging to mate of mine, who’s an ex state champion cyclist and bike company sales rep, the idea of a slick road tyre was suggested to prevent me going through a tyre every second ride. A local bike shop in Blacktown sorted me out and $35 later (I know it sounds pricey) I have the best back tyre money can buy. The upshot is that tonight’s test run did not even leave a mark on the new tyre where the motor would chew great chunks of rubber off the old tyre. Another interesting fact is that the tyre is designed to run between 85-110psi of pressure. This and a sidewall strong enough to hold up a small truck mean it can hack the punishment dealt out by the crankshaft and tensioning spring with ease. Not bad for a bit of fun. Hopefully we can sell it off on Ebay when we get bored of it. That might be sooner than later…but more of that in a minute.

Now for the brake. Brian’s preference was to put a bike calliper on each front wheel, however, I wasn’t such a fan as there is now real way to balance them. That’s ok for ‘turning brakes’ but it’s actually more dangerous if you have slow down in a hurry. So, as per the original plan, the back pedal brake is being utilised. An old chain was welded on to the sprocket and it goes down and under the seat where it’s connected by a cable to the pedal. The pedal is just flat bar bent and welded with a small cross brace. There were two mounts for it welded to the front and I even put a zero stop on the top so it can be tensioned properly. Ok, so how well does it work? Well against an open throttle not amazingly well, as you can imagine. However, it will stop the engine on idle and put a serious dent in the engine’s power on full revs, which is probably as much as you’d want anyway.

As you can see the setup is very simple but it works well. I took it out for a test drive tonight and had a few silly problems. The fuel tap rattled shut and a couple nuts vibrated off, but that was all easily fixed. All in all it was top fun. Anyway, might be time to sell it off as a good cheap chrissy present for some trouble-making teenager. As I've said earlier, there’s loads of development left to be done, but I’ve got a new project in the design stage. Yes that’s right, I’m designing a Khanacross special. Liz is philosophical about it at this stage but I know she’ll come round when she realises it keeps me out of trouble. Keep an eye on the webpage for more details.

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