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Written by Scott G. Evans - National Tech Director
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Tuesday, 01 June 2004 00:00 |
From the National Tech Director
During the course of our season, we are organizing the Team's Cup events and to date have conducted both the Southwest and Southeast events. One of the side benefits of this program from both the race conduct and technical scrutineering standpoint is to gather information from our constituents about the comparison between their local Challenge events and those represented by the "national" team. In this light, it has been often expressed that there is a general lack of thorough technical inspection happening at the local level. There seems to be an understanding that since the engine is sealed that technical inspection is a costly, labor intensive tactic reserved only for large, national events.
The intent of this issue of "MaxTech" is to de-mystify the post-tech process and make it more uniform across regional boundaries. Not only will this help alleviate any technical issues that may arise locally, it will also prepare our constituents for the national events so that they know what to expect and how to prepare themselves and their karts.
For cost control reasons and in accordance with Bombardier directive, we continue to recommend "above the seal" methods for post-tech at the local level. However, there is a good deal of inspection that can be conducted that does not require the breaking of seals. All of these points are "performance oriented" and therefore worthy of field verification. Local Challenge coordinators are encouraged to distribute this information to their technical personnel and require that verification checks be made on a regular basis, not only for customer ease of mind but also in general protection of program integrity.
It is recommended that a few of these items be verified for conformance after each qualifying session, heat or final race. For expedience, it is generally not necessary to make a "full" verification after each session. These quick and easy checks can be done at random and keep the program and its constituents running at its best. Please feel free to contact me with any required clarification requests at
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or call (530) 623-1664.
Scott G Evans
US RMax Challenge
National Technical Director
The following "quick and easy" checks are derived from the actual version of the ROTAX Technical Specification where the legal description may be found. The text included here is for reference and clarity only.
Intake silencer
- Must be intact with no modifications allowed.
- Filter element must be installed and intact (full length and width).
- Check to make sure the airbox is securely in place on the carburetor adaptor boot. Easily done by visual verification while they are in line at the scales. This allows more air to flow to the engine and is definitely a performance advantage.
- Airbox position and bracing is free in rain conditions.
Carburetor - The letters "VHSB34" and "QD" must be cast into the body of the carburetor.
- The complete inlet bore must be "as cast" with no machining allowed.
- The slide must be stamped with the number "40" and the bottom of the slide must be "as cast" with no machining allowed.
- The needle jet must be stamped with "FN 266" and the jet needle must be stamped "K27" only. No machining or polishing allowed.
- 5.2 gram floats only. Marking is found on the flat "bottom" of the floats.
- Idle jet and idle jet insert #30 only. Marking is found on the parts. Remove the idle jet and the insert is found underneath. A small, flat-blade screwdriver is required for removal.
- Unaltered, Series Two atomizer nozzle only. (Brass piece that sticks up into the venturi bore. Series Two nozzle will have half of the cylinder machined off. Series One will be a full cylinder and noticeably shorter than the Series Two nozzle. Check to ensure that the nozzle end is unaltered with no material removal, polishing, corner breaks, etc. permitted.
- The fuel filter in the body of the carb must be in place.
Intake manifold (rubber carburetor attachment boot) - The entire intake manifold is subject to visual inspection for alterations. No alteration of any type is allowed. The intake manifold is molded with a special surface treatment such that, when broken by grinding, cutting, etc., the rubber substrata will show deterioration after exposure to fuel. This type of alteration is easily apparent to visual inspection. A flashlight would be a good idea.
- A small corner break at the junction of the inner contour and the carb mounting face may be present to 1mm wide maximum. In reference to this corner break, there was a production lot or two of manifolds produced by the sub-contractor where they let this manual corner break get a little "out of hand". Since this rule was enacted, I have seen a small number of them with breaks up to 2.5mm, though none of them showed any degradation of material that would indicate tampering. The vendor has since fixed this problem, but I would ask that you use good judgment when evaluating this element. Blatant trimming is definitely a problem, but you should be aware that some inconsistencies do exist in the field.
- Additionally, make sure by verification of part number cast in the manifold that the FR is using P/N 267 915. The DD2 manifold is P/N 267 410.
Exhaust valve - The entire exhaust valve assembly must be as supplied by ROTAX with no alterations allowed.
- The exhaust valve must be operational. (Remove cover and check to make sure valve is free moving and not "blocked".)
- Please be aware that there are new bellows, new pistons and the "mushroom" adjustment knob for the exhaust valve. All are legal.
Exhaust pipe - Visually inspect exhaust pipe for stock configuration.
- Two, OEM springs only. Silicone may be applied for vibration dampening. Wiring of the springs may be for retention to the pipe or the manifold, but not both. Contiguous wiring together of the pipe and manifold is not permitted.
Cylinder - Please ensure that the FR is using P/N 223 997 for senior and 223 999 for junior. DD2 cylinder is P/N 613 930.
- Additionally, have them remove the pipe from time to time and check for alterations to the exhaust port and passage with a flash light.
Ignition - Please check for three pins only for the FR engine. The DD2 ignition has six pins.
- No additional ground straps are allowed.
- There are only two acceptable spark plugs. Denso Iridium IW.. or NGK BR..EG. Any heat range is acceptable for either plug, for example, Denso Iridium IW27, IW29, IW31 or NGK BR9EG, BR10EG are all examples of legal plugs. An illegal plug would be an NGK BR10EIX or B9EG, for example.
Restrictors - Verify MiniMax restrictor diameters: 19 +0/-0,2mm for the intake side, 22 +0/-0,2mm for the exhaust side.
- It has been recently recognized that there was a production problem with the black intake restrictors and they may be oversized "as-supplied". It is recommended that all MiniMax intake restrictors be inspected in pre-tech scrutineering and replaced if found to be oversized. SSC and Bombardier have a warranty program in place and any discrepant restrictors will be replaced free of charge.
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