Tuning Hints  

The Easitune led colours are intended as a guide, to enable you to run your engine at what you determine is the optimum mixtures, with repeatability, to  ensure your  testing is valid, and not just that you ran slightly different mixtures that test session.

As a general guide, air cooled engines need to be run at a much richer setting, than what is possible with a water cooled.
In situations like speedway, even richer settings are necessary, due to the constant load on the engine with no “backoff”.

The “perfect” mixture is when the richest red and the “lean” green are on at the same time. HOWEVER, if you ran an aircooled  twostroke at this mixture setting, it would rapidly get hot and seize, whereas a fourstroke watercooled could potentially run quite happily.

For ashphalt Kart motors, an aircooled needs to run much richer all the time,to achieve sustainable laptimes, without “going off” or seizing.

  A typical ideal scenario for an acceleration run would be:

  • back off/brake,
  • lights wiil go red,
  • accelerate,
  • lights flash amber,
  • lights go to “rich green”
  • as revs go thru power peak, turns to “lean green”
  • flashes between rich red and rich green for a short period
  • ending back in the rich green for the last portion of the straight, and preferably just going into amber as you brake for the corner.  

This gives you, all things being equal, a sustainable laptime. If used in conjunction with a head temp/tacho, and a laptime, you can work out where you have to run the mixtures, for your best laptimes.

A water cooled engine can be run potentially leaner, on a constant basis, but a good idea if you want to push the envelope, would be to wait till you are due for a topend rebuild, and do it then.
Generally, if you are a little lean, the head temp starts to climb, and the engine goes off, losing bottom end as the first symptom.

WHEN YOU HAVE A PROBLEM, both engine and chassis, it often becomes apparent during the acceleration period, showing up as a “leanout” or a very rich area.
A chassis binding up, will cause leanout as you exit the turn, as the extra load on the engine, causes the engine to need more fuel, which the carby can’t supply on it’s present settings.
Car carbies have a powervalve fuel supply circuit, to cope with extra load situations, but the concentric twostroke carby relies on the backoff time to load up the crankcases with excess fuel, which is why the lights flash amber on initial acceleration, if the carby is right. 

When a situation arises, due to the track nature, or a chassis problem, and the engine is observed with a lowspeed leanout, choking, or more roll time, or not closing off the throttle fully, can help allieviate the problem.

Midrange leanout is a big problem, in Karting, as the carby is asked to meter fuel over a wide rev range, and as your midrange is the power peak area, and the area of most fuel requirement, it is sometimes impossible to “get it right” all the time.

When you have problems, tell your engine builder ALL the info, including the problem areas, what the lights are doing at all points thru the rev range, so he can determine what to do.