View Full Version : micro rpm's
05-23-2010, 12:38 PM
had a race last weekend where a competitor was turning atleast 300-400 more rpm in a FIXED gear class. My pro tuner nor tech guy could not figure it out(they all heard it and thought the guy was cheating) We where on the fence regarding a advantage because we crossed the finish side by side and set track record but could not figure out how they where doing it?:confused:
We checked tire sizes.
any other thoughts?
should the crank case have a breather tube on it?
05-24-2010, 08:59 AM
It could be because of the cylinder. Minor differences in port heights could provide alittle more RPM.
Were you and the competitor running 09 cylinders or one running 09 & other not?
For the crankcase breather tube, I assume you're referring to the left side gear box area. There is a spot to run a tube on the left front fill cap but most people do not run a tube. I think from the factory the Rotax comes with a yellow cap fitted to the gearbox vent. I put a short piece of fuel line on the vent and then screwed a M6 bolt into the fuel line to seal it off.
05-24-2010, 10:55 AM
We both had 09 cylinders.
thanks for the response.
05-26-2010, 02:58 PM
As of this morning, this is no longer legal.
Per Don Moormeister.
SIDE COVER BREATHER MUST BE FUNCTIONAL
Any effort to change “Breather” function will be a post race technical inspection item.
Violation will result in disqualification from competitive element involved.
To be clear, this prohibits folded hose on breather.
National Tech Director
United States Rotax Max Challenge
05-26-2010, 04:09 PM
Edward - could be a number of factors effecting RPM difference but I would think it is more than likely in carburator settings - jetting, float bowl height, clip position.
It could be that you had slightly better low rpm off the corner, but he had slightly better high rpm at end of striaghts - thus the reason for still coming across the finish line the same. Caveat - I am no expert, still learning myself.
At Infineon raceway this last weekend (Northern California - sea level) our Micro was turning between 9800 and 10,000 as a high RPM one day.
What kind of RPM's were you seeing and what were the weather conditions?
05-27-2010, 12:04 AM
sorry i was running 2 classes that weekend w 1 micron, i chose the other class to keep micron on.:(
weather was 75 ish in final and bad air real humid. 100 ft above sea.
06-02-2010, 11:38 AM
well i wanted to update everyone on my original question.:p My Tuner ran into my competitor at a regional race where my competitor was still out revving everyone so he kindly told tech they better start checking gearing. At the race i was in against him they did not check, I even assumed know one would be crazy enough to run a wrong gear in a spec class.(and i bet thats what they where hoping for) BUT BAM! what do you know he was running the wrong sprocket in the front DQ!:eek:
I guess that got solved:rolleyes:
vBulletin® v3.8.4, Copyright ©2000-2013, Jelsoft Enterprises Ltd.