Category Archives: Setup

Rotax Mini Max MSA Homologation

The Rotax Max Senior and Rotax Max Junior Homologation documents for racing in the UK under MSA rules can be found in the following document. Below is quick summary of the main measurements that you should check.

Squish GapMin:1.20mmAverage of both sides using 2.0mm solder
Volume of Combustion Chamber11.4cc At TDC Use Class A or digital Burette
Exhaust Flange restrictor Max:20.3mmOne original gasket
Height of Clutch (thickness)Min:11.45mm
Thickness of Clutch ShoeMin:24.10mmTaken at 3 open ends 5-10mm from groove. Must be fully closed.
Diameter of outer drumMin:89.50mmmeasure at shoulder not open end of drum
Inner diameter of clutch drumMax:84.90mmmeasure on contact area
Inlet Throttle restrictor33.5mm +0.2/-0.0mm


OTK Seat position guide for Tony Kart, Alonso and Kosmic

OTK Seat Position


Here is a chart showing the recommended seat position for OTK Karts. Including Tony Kart, Alonso Kart and Kosmic. I recommend anyone looking for advice on seat fitting should take a look at  In the UK you will see the majority of drivers using Tillett seats. Looking at the fitting guide Tillett Seat Fitting Guide.pdf 


Kosmic Knowledge Pack 2008

Found an copy of the Kosmic Knowledge Pack 2008 in PDF format. Good basic information  relative to all OTK karts Tony Kart and Alonso. Below is an extract of the index page :-

  1. Seat Installation
  2. Front-Track Adjustments
  3. Rear-Track Adjustments
  4. Caster/Camber Adjustments
  5. Front-Ride Height Adjustments
  6. Ackerman and Steering Adjustment
  7. Rear-Ride Height Adjustments
  8. Tire Pressure
  9. Axle Chart/Stiffness
  10. Tuning Bars
  11. Rear Hubs
  12. Braking System
  13. Basic Wet Weather
  14. Conclusion

Kosmic manual

Warmer Weather and Tyre Pressure

With weather temperatures in the high twenties we had a good chance to practise getting the correct tyre pressure over a short race.  The rule that I have been shown that seems to work is the following :-

  • Get yourself a good tyre pressure gauge and follow these simple rules
  • Set the pressure to around 16 to 24 psi
  • After each session immediately check the pressure
  • If they have gone up less than 2 PSI then they are correct
  • If they have gone up more then they are too high s drop them
  • If the pressure remains the same they are too low

Jenson took another second out of his personal best for Camberley, a good result as we have not been to the track for over two months. It was also good to have Dom come down to watch Jenson.

Comer W60 Karting Tips

We have been running an old kart with a Comer W60 Engine and one of things we wanted to do was use this Blog to share information and hopefully some tips. These are some I think will help any dad new to Cadet Karting.

  1. Ask Someone. Don’t be afraid to ask someone at the track if you have a question. Often the most experienced and detailed advise comes from the dads who have moved up to higher classes such as Mini Max and use to run your calls last year.
  2. Tyre Pressures Get yourself a good tyre pressure gauge and follow these simple rules
    1. Set the pressure to around 16 to 24 psi (See rule One 🙂 )
    2. After each session immediately check the pressure
    3. if they have gone up less than 2 PSI then they are correct
    4. if they have gone up more then they are too high s drop them
    5. If the pressure remains the same they are too low
  3. Remove the Carburettor when you have finished for the day and store it in a clean sealed bag on small box. When you get home give a clean and dry the internal seals. Don’t put it back on until you you next go karting
  4. Make Notes of how you set-up the kart and how well it worked or didn’t. I note the following
    1. Number of teeth in Cog
    2. Tyre Pressure in and out
    3. Rear axle width and Front spacers
    4. What Engine, Carb, Spark Plug, tyres we used
    5. Engine Running time
    6. Jet or Carb setting
    7. Seat stays
  5. Prepare the Kart at Home the best use of your time at the track is practising or racing not putting the kart together. As soon after each session clean and inspect the kart and order any parts so that you can fit them before your next session. Also put the correct rear cog on for the track you are going before you arrive
  6. Starting your Engine is something you need to practise at home. Most people flood the the engine or break the engine pull in the stress of getting out. Have a spare Plug and Spanner to change it in your pocket. Don’t start it too soon as you will oil the plug. Use short steady pulls to avoid the cord snapping.

Kart Data Logger and Lap Timer for $5

Jenson goes for the pass

Karting is expensive so we are always looking for savings. I was cynical that an application called Trackmaster on the Google Android Market Place that ran on my T-Mobile G1 would be any good. To my pleasant surprise the application from Trackaroo does a really good job and is definitely worth the money just $5!

Jenson has used it at both Camberley and Forest Edge and helped me see things like his engine is well down on power and he is flat to the floor on the straights.

What you Need

All you need to start getting lap timing and mapping data is a Google Android Mobile Phone with GPS and the free Google Earth Application.

Screen Shot from Trackmaster

Lap Time Summary

The application can export the data to excel format or show you on the screen

Lap Top Speed (mph) Avg Speed (mph) Distance (miles) Time

1 40.82 25.68 1.10 2:33.126

2 40.26 28.24 0.53 1:06.064

3 40.82 26.06 0.54 1:14.830

4 38.59 28.16 0.53 1:07.857

5 33.64 5.74 0.12 1:35.562

G Force for acceleration and braking
Click to see bigger version

The chart above was created by saving the data in excel and then using Google Documents to to create a chart of each of the laps Acceleration.

Click for bigger version
Click for bigger version

Mapping the laps with Google Earth

Using the free application Google Earth you can save the data into a KMX file and then overlay each lap onto the Track. Below are examples from Camberley and Forest Edge.

Click the image to see a larger version
Click the image to see a bigger version
Clicck on the image to see a bigger version
Click on the image to see a bigger version

Lap Start and Sectors

Before you go out on the track you need to set-up the lap start and as many sectors as you like. This can either be done on the phone or using Google Earth.

Below shows the splits we used for Forest Edge

Press to see a larger Version
Click to see a bigger version

I would recommend anyone who doesn’t have any lap timer to get an Android phone with GPS and TrackMaster it works well. My only disappointment is the sampling frequency of data needs to be higher to cope with tight kart tracks and I need to work out a better place for the phone than just zipped inside Jenson overalls. I am sure Trackaroo will put Kart features in if enough of us use it.

Wish List

These are some of things I would like to see in the next version

  1. Increased frequency to cope with short tight kart tracks
  2. Theoretical Best Lap (The best sector from each lap during a session)
  3. Best Rolling Lap
  4. Ability to quickly change drivers and vehicles and  setup for each session
  5. Include Kart set-up information – gearing, axle widths, carb jetting, engine etc.

karting jenson IMG_8023 e mail

Correct gearing for different kart tracks

The first question you ask when you visit a new kart track is what is the best rear sprocket to start my testing with? I found a useful page, that from our experience in Cadets and Rotax Max Senior is a good starting point. Its important  that you test yourself.  Newer drivers should normally start with a higher gearing and drop down a tooth at a time as you become more familiar with the track.

Remember less teeth = higher speed on the straights but slower out of the bends and more teeth the opposite.

Thanks to Linconshire Kart Racing Club for maintaining the useful page that covers Cadets,  Rotax,  TKM and Biland.

Circuit Gearing