Gearbox Kart! - Update 15/06/11 - Shake Down!

Hmmmm kx85 might not be the most reliable engine though :L Still, I'm thinking about having a go at building one

Pfft, who needs brakes Cant wait to see this finished, gonna be rapid! Especially as you don't need clutch when shifting up, acceleration is gonna be unreal

Are you rigging a quick shift on it to kill the ignition for quick clutchless changes?

Expecting an update sometime this weekend..... ;D

I have had fun this week, concluding in lots of smoke at the end of today, If you just can’t wait scroll to the bottom to watch the video clip

Tuesday evening after work I took the rather tatty high back seat and set to work on it, there were so many holes in the thing it was doing a brilliant impression of a colander! Initially the holes were filled with P40 fiberglass paste, this filled the bigger holes well provided I taped over the other side to prevent it just pushing through the holes. Once set any straggling fibres the flashed back with one emery paper, the seat was cleaned ready for the fun / stressful bit.





To make the seat a bit more presentable I decided to give it a cosmetic layer of carbon, using the left over stocks from the imp intake system, initially I cut out a template to use as a guide for cutting the cloth and making sure that I had enough material. I decided to cover it in two sessions, first up were the sides, then a strip covering the back and bottom.



I then got out my super sharp shears to cut the cloth



Once the first part was cut out, I laid it onto the second section and lined up the weave, not essential and probably not worth it, but it makes me happy



I mixed up some chemical resistant resin (I guess the seat is going to get oily?) which should hold up well next to that smoker, and set to work. The results are pretty cool I think –



The centre section was a little easier as it was just a straight piece of fabric, it still needs flatting back and giving a coat of lacquer, nearly there though.



I whipped up a reducer on the lathe for the cooling system –



So that can all go together now.

Then bing bong, door bell, and the arrival of my braking system!

I immediately set to work pulling it apart to clean and bleed it, pads out, pistons out, seals cleaned, bores polished, general clean, and back together! The same was performed on the master cylinder.





Then came the fun of bleeding it, how do you bleed a brake system without a master cylinder reservoir? You make one!

First the fitting on the master cylinder, turned out to be 1/8th bsp and I just so had some fittings with the correct thread –





A bit of rubber hose and an empty dry evian bottle, and you head the head of fluid needed –



The fluid was run through under gravity until it was clear and bubble free, system bled! The pads were contaminated with fluid, so I used a trick learnt from another thread, stick them in boiling water for a while and the fluid, being hygroscopic, gets pulled out and dissolved in the water. Once dry they were fitted. Now it was simply a case of bolting on and getting the disc in the correct position.

Master cylinder on –



And calliper on, just need a clevis for the pedal and it will all be working –



I had a go at the fuel tank, cleaned it and then renewed all the hoses, as they were quite perished and hard.
First the pick up, including a new sealing o-ring –



Then to the fuel pump, first it needed mounting, I used two piece of hard rubber pipe to isolate it from the seat and prevent the glass seat from fretting. New pipes were then fitted all round –



At this point I got all excited and decided to build the engine! After reading the threads about the Tomos and Puch I had learnt a few little tricks to make my life a lot easier, like putting the piston in before you fit the gudgeon pin, and fitting one of the circlips before pushing it through to stop it pinging out the other side!

First of all I wanted to take all the sharp edges off the ports, I have been told and read that this is a good idea to ensure a long ring life, I just went at it carefully with a small fine rats tail file –



Next up I was not happy with the shape of the exhaust outlet, it was machined in to the cast surface and had a sharp edge and non continuous bore, a quick attack with the dremel was necessary, scary doing it to brand new parts! The result was smooth and should flow quite well –



Carbon reeds were fitted to the reed block, these were with the barrel kit, so I’m guessing well matched too –



And the whole lot bolted together, I also fitted the chain and got my lovely wife involved in the next bit (Click on the picture to view the vid) –



Hahah! She lives!!! Ran like a dream too, I was seeing hours of fiddling to keep it running at first

So now all the needs doing is –

Gear linkage
Fill the cooling system
Fit the brake linkage
Tie back all cables and pipes so that they are neat and tidy,
Fit lambda sensor boss
Properly mount the exhaust pipe
Mount seat
Take it for a run!!!!

Thanks for reading guys,

J

Hey guys, I am ruined, so so tired and aching all over, this can mean only one thing, my first practice day!

The past couple of weeks have been fun with the project moving along well, so well I did not get a huge amount of pictures, most of it was cleaning and tidying which is quite frankly pretty boring!

One amusing incident occurred after the first heat cycle of the engine, it became apparent that the fuel pump was not really pumping, at all infact! Initially I thought that the vacuum line was not in the best position resulting in a weak signal to the diaphragm. I found another nickel brass fitting that was vaccum rated, then picked a good position on the inlet manifold to situate said fitting.

Fitting –



Tidy install -



I plumbed it all up and started the engine, and thought “the fuel is a bit foamy in the pipe, why did the engine just stop? Ahhhh the pump is emptying the flat chamber and filling the tank!” Oh yes, I am a certified plank, swap inlet / outlet and off she goes :-D This however will come back to bite me later, keep reading to see how.

There were a few other highlights, the best of which was the fitting of my tuning device, I am no master of the dark art of plug cuts and maps of Australia on piston CROWNs, so I need electronic devices to tell me what is going on.

This is what I have used to tell me exactly what is going on post combustion –

www.innovatemotorsports.com/products/lc1.php



An innovate LC-1 wide band lambda controller combined with a Bosch sensor, this outputs a nice linear signal from 10:1 – 18:1 air to fuel ratio as a voltage.

The sensor needs a boss putting into the exhaust, preferably quite a distance from the port to ensure it is only reading burnt gasses not transfer from the inlet charge, so I picked a point half way along the expansion chamber and the only disadvantage was the lack of heat to keep the sensor clean (like a spark plug it needs to run hot to prevent carbon sooting it up). The section selected was also double skinned to suppot the weight of sensor and boss combined, it should help prevent fatigue fractures.

Hole drilled –



Boss ready –



Welding –



Finished! –



Various plans were cooked up on how to rear / log the data whilst on track, finally I remembered that I had one of these sitting in a cupboard for a rainy day –

www.14point7.com/UAFC.php

Now the main feature of interest to me was the fact that it can log two 0 – 5v channels for 27 mins, ideal for a track session followed by digesting numbers and deciding on jetting.
This was all hooked up and ready to go, unfortunately when I tried to download the first log the file was corrupt  I tried a couple of times, but it would appear that my very early unit (it was part of the beta testing) has some firmware issues. The solution was simple and in fact worked very well -



Yep, a multimeter, 0-5 volts in, if it is at 2.8 then we are happy, over 3 and the world will end, under 2.5 and a milkfloat will have the legs on me!

By this point is was 12pm the night before the test day, the kart was ready, tools selected and boxed ready, time for a fitful nights sleep and dreams of soft ceased engines!

6am today I was up for my run, Michelle my wife was up and packing lunch before her run, both ready to take on the world, ish.

The citroen was prepared –



And filled –



On the way to the track we picked up a set of micro drills for jetting, and 10 litres of BP ultimate.

We arrived at 9.30am, unpacked and re-assembled the minor items removed for transport, Michelle cooked bacon sandwiches, the kart was warmed up and after a chat with the nice old chap running the show (I cant remember his name, but he made me laugh!) we were ready to go.

Now before you laugh at the following pictures, I really did not care what colour my suit was, I wanted a good quality item that fitted well, the result was this little number –



Yes, from now on I shall be known as ‘the golden boy’

From then on it was a steep learning curve, keeping out the way of the much faster people (yes there was a girl on track and she was much faster than me!), keeping an eye on the engine, running it in well, checking the fuelling, and oh yeah, learning how to drive the bloody thing!

We tried different starting techniques too, the best so far is a push from someone, I tried myself, but I have not got the smooth transition hop into the seat down yet –







Fuelling was pretty damn good from the off really, seeing around 2.8 – 2.9V under hard acceleration, which is around 12.5:1.

Then after a particularly punishing 15mins the engine died, in fact it felt like a soft cease, power dropping off steeply and the engine reluctant to rev. balls, balls balls balls.
I let it coast onto the grass just after the first hairpin and retreated to a safe distance, the marshall called me over after 20 mins nearing the end of the session, he said that I could have one go at push starting it between this session and the next cadet session, if it was a no go the I would have to push it back to the pits 
Michelle ran back to the car and collected the can of ‘start ya curse word’ and I gave it my best shot, nothing, then I realised I had not switched it on, I gave it a cheeky second try and bang, straight into life!

For the next 3 sessions this happened, I was watching the AFR’s and it would run full lean just before dieing, if I could keep the motor running it would recover after ½ a lap and resume progress as normal.
The it dawned on me, the pump, it was not running enough fuel to keep the engine running at full tilt along the two straights before that hairpin, so it was emptying the float chamber and would quit. Slowing down would let the pump catch back up and then back to normal!

Over the day I did 5 sessions of around 15-20mins, and I can tell you now I am shattered! Michelle decided against running today, it was just too daunting learning now to drive a gearbox kart like this, whilst other more seasoned racers were lapping a lot faster. We have a plan up our sleeve so that she can get some seat time and settle in a bit.

So the whole day without any mechanicals, I was happy! And I cant wait to get to the next one, a bit fitter and a whole lot more confident.

Parting shot, a little video of the kart in action, short but sweet, and a couple of arty shots



(click on the picture)






I hope I have not wittered on too much.

Cheers,

J

Seems fine, the LC-1 is quite good in that you can change the output voltages and filtering, so rather than instant update of around 400hz reading all the little gas pockets and fluctuating wildly, you can sample at 10hz and see a smooth increase / decrease. Certainly worked today for me!

Cheers

J

I was just thinking the same.

Looking good there. Cracking little project

We used to go to Whilton every month. We raced Junior TKM, Senior TKM, Junior Rotax and Senior Rotax. I preferred the Rotax's for their pace but they were a git to get the setup spot-on. We even did the endurance series one year with a Rotax but you had to work hard to beat the more fuel efficent 4 strokes.

Back to your build, I'm really impressed with what you've done. more vids please.