vortex’s blog

Finally I was able to get out on the track, after buying my kart in February and a KT100J motor not long after.
I got the engine for my kart about 2 months ago, a brand new in the box KT100J motor for running Senior National. Once we bolted it onto the kart we put about 200 laps onto the motor to get it nice and bedded in, new engines require a certain amount of running and heat cycling because of the poor materials and construction methods used in Yamaha kart engines (they’re literally recycled aluminium, well the head and fins are and probably the crankcase).

Once we thought we had completed running the motor enough, we sent it off to our engine builder for blueprinting and rebuilding. Our engine builder has never been one to offer how well he thinks a motor will go but when this one was built he was incredibly happy with the results, and now having raced the motor I can see why

Saturday finally came and it was time to hit the track. On Sunday we were to be racing Senior National Light (140kg kart and driver) at the Bolivar Raceway here in Adelaide, so we headed out there for some practice. The meeting was to be run in a ‘clockwise’ direction, which is unsual for an SSKC meeting, but it was run in this direction to give competitors practice for the up-coming South Australian State Sprint Karting Titles which will be run there by the Go Kart Club of South Australia in the clockwise direction.

Anyway, we went on to get some base times for the kart and motor on the track. In our first run we hit the track, we were damn close to it. Averaging laps of 42.00 and 42.10 it was a great start to the day; but more was to come. We had no idea of what a base time around the track was either so we were very happy with the first times for the day.

As the day wore on we tuned the kart and engine some more and were able to get down to 41.6x for the best laptime of the day. This was a pretty good time, especially considering I was 152kg kart and driver combined weight; 12kg over the minimum weight. The front runners in Senior National Light and Junior National Heavy (same motor and tires, also 140kg kart weight) were averaging 41.2 / 41.3 and they’re bang on the weight for the class. Commonly people say for every extra Kilogram over 5kg of the class weight, costs 1/10th of a second per lap. Figuring that I’m 12kg over the weight, allow for the extra 5kg, that gives me an extra (theoretical) 0.7 seconds per lap I could gain for free. Might not sound like much, but karting is a game of tenths of a second, a tenth of a second can be the difference between winning and loosing, or being on Pole or on grid 20, karting is often that close

Sunday, Race Day, finally comes.
We arrived early enough (after getting held up for 15 mins waiting for some stupid foot race) and got the kart scruiteneered and my licence signed in. In practice we went out on to the track close to another Senior National Light racer, and I was able to catch, pass and drive away from him quite easily in the practice session. A very promising start

Race one
Race one was 10 laps and because i’m coming back to the sport after a long period of not racing (7 years to be exact) I have to start on a probationary licence again, which means I start from the back of the grid for 3 race meetings. I ended up finishing 4th (out of 4 :p)  because the kart wasnt as quick, the tuning was all up the creek. I was quick again at the end of the race once I did eventually get the tuning sorted, but it was too late

Race two
Once again off the back of the grid again, and the kart was a bit quicker this time because we realised the tuning was miles off in the previous race and fixed it for this race. We also made a gearing change and this didnt seem to help, but it didnt hinder too much. I was able to get past the 3rd place kart and finish 3rd.

Final Race
This final race was 15 laps and I was once again off the back of the grid again, but was able to  get up the inside of the 3rd placed kart once again and and sit in 3rd for the whole race. This time we made a few other changes to the setup, gearing change once again and the exhaust length as well. I was able to keep with the front two drivers this time for about the first 6 laps, my times were consistantly down in the 41.6 - 41.9 range, so the gearing and exhaust change was very beneficial to the overall speed of the kart. Finished in 3rd, 5 seconds behind the winner and a long way in front of the 4th placed kart.

Overall we are incredibly satisfied with the results of the weekend, a lot of good data was obtained for the State Titles later in the year. We are over the moon with the speed of the motor, to be 3 - 4 tenths of a second behind the leaders per lap when i’m 12kg heavier than them is huge.

Now to embark on the next stage, loose the 12kg I need to get that 7 tenths