Rule changes and upgrades for 2017

Tech Regs rule amendments for Rotax Max engines.

I have some suggestions in regards updating the Rotax Max Tech Regs. There are a few out of date rules and a couple that are contradictory from one rule to another. There is also the need to include EVO parts in various places. This is a good starting point for discussion.


#1 EVO exhaust is currently not included in the rules for Junior Max engines.

Page 11, rule (xxi) the last line needs to have the EVO style included.
This will then read : Junior class to use only Type B or EVO style exhaust as supplied by ROTAX.

#2 As from November 1st 2016 there will be new ECU’s supplied for the senior and junior Max engines. We will need to list the two new ECU part numbers relative to their engines.

#3 Page 10 rule (xv), the 2nd last line should make reference to the fact it only is in relation to the Denso brand coil, it is not referring to the Dellorto EVO coil.

Last 3 sentences of rule (xv) are then : No modification to any part of the ignition system and/or crankshaft to alter the ignition timing or rev limiter is permitted.

The DENSO ignition coil must have three pins at the terminal.

Battery make is free.

#4 The engine measuring methods used with the Rotax Max worldwide have changed in the 12 or so years since our rules were written. The cylinder head volume and exhaust port open timing have both been removed as items to be checked, and instead gauges supplied by Rotax are used to check dimensions of individual parts. There are now a combustion chamber profile gauge and an exhaust port height gauge, and there is no plug for measuring cylinder head volume..

Our current rule (xxii) on Page 11 already states that the gauges are to be used for compliance checking, which actually puts that rule in direct contradiction of the various rules that specify limits on cylinder head volume and exhaust port opening timing.

To go with the gauge checking method would allow rule (xxii) on Page 11 to remain as is.

This method of engine measurement by genuine gauges will also require the inclusion of squish clearance limits as used by Rotax.

Rule (i) on Page 9 would then be deleted altogether.

Rule (iii) on page 9 will need the an extra sentence added to the end of it.
ie : Combustion chamber insert: Only Rotax part number 223 389 or 223 389 1 or 223 389 2 may be used. The name Rotax or ‘made in Austria’ must be cast into the combustion chamber insert. No additional material may be added except to repair the spark plug thread and or spark plug sealing surface. All machined surfaces may be re-machined. The insert must retain both squish band and spherical combustion chamber. An ‘O-ring’ must be fitted Minimum squish clearance of 1.0mm to 1.5mm for senior Max engines and 1.2mm to 1.8mm for junior Max engines, measured using 2mm solder or tin wire. The average of the two measurements taken from the left and right sides of the bore will be taken as the actual measurement for an engine.

On pages 11 and 12 following directly after rule (xxii) are two sets of instructions titled Port timing check with Piston Travel Gauges and Method of measuring cylinder head volume, and a diagram at 9.5.11. All of these would then need to be deleted completely.