Tal-Ko Racing has issued a number of recommendations to drivers in Formula TKM as a result of some problems which have occurred in TKM engines that have run on the British Championship control fuel.

Extensive inspection and metallurgical testing including independent tests has shown that the engine components are of good top quality and indicate lack of lubrication as the likely cause.

Since the failures have only happened in a relatively small number of engines it would indicate potentially a problem in the mix of the control fuel and oil. This underlines the need for stringent care in preparation of the fuel/oil mix.

Says Tal-Ko’s Alan Turney: “We are anxious to prevent competitors suffering unnecessary expensive failures resulting from lack of lubrication. Why this is happening we are not sure and we have made the fuel suppliers and Motorsport UK aware of our findings and concerns. We fully support the principle of control fuel but feel we need to issue this advice.”

The observations and recommendations for using this fuel from Tal-Ko are:

Engines being taken apart for servicing that have been running on the control fuel appear much cleaner and less oily inside than normal. If this is the case then your engine has probably been running with too little lubrication and may have suffered internally as a consequence.

The item failing is the crank big end pin which is suffering excessive wear and breakup of the case hardening in the 6pm position. Owners and engine builders are recommended to check its condition and replace it and the big end bearing immediately if it appears to have excess surface damage.

Mixed fuel can separate when left to settle. To avoid all risk Tal-Ko recommend mixed control fuel should be disposed of safely after every race meeting.

Shell M oil should be used at a minimum ratio of 16:1. That is 312ml to 5 litres of fuel. One driver who has not had any problems, but saw the reduced level of lubrication in his engines, moved to a mixture of 14:1 which is 357ml to 5 litres and has even raced on 13:1 which is 385ml to 5 litres. He has had no problems and is lying in top five in TKM Extreme champs.

Tal-Ko stress the importance of ensuring complete thorough mixing of the fuel and oil and recommend mixing in small quantities of only 5 litres at a time and between races remove fuel from tank back into the can for thorough shaking/mixing before putting back into kart tank just before each race. Specific information on carb settings is available on www.tal-ko.com

Critically the low jet should always be at approx. 2 ½ turns open and the high jet set at 1/4 of a turn out at a minimum. If running carb restrictors then the low jet remains at 2 ½ but the high jet setting will need to be increased. Using a very different setting can in itself cause engine failure.

If ambient temperatures are high then naturally the carburation should always be set with the high jet set further out to increase lubrication and cooling of the engine.

If any competitors have experienced any technical difficulties they believe related to control fuel /oil they should contact TKM in the first instance who will pass them on to the fuel suppliers and Motorsport UK.