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We set up our engines so that they will not idle. The reason, when we let off the gas, we do not want the engine to push us forward under braking
Doug – Thanks for the reply. I’ve got a few more questions for you or anyone else who may be willing to give their $.02. I’m asking all these questions out of curiosity, I have no opinion as I’m way too new for that. Just trying make it up this steep learning curve.
Wouldn’t a properly set up idle speed allow the clutch shoes to disengage, thereby no providing any resistance to braking? What method do you guys use to get it not to idle? Do you back the idle adjustment screw all the way out, or some other method?
What do you all think about warming up an engine on the stand vs. under light load (ie. taking it easy around the track)? I’ve heard that both can damage the engine, what’s the best way?
What’s an ideal operating temp for the Rotax engine?
Sorry here for the questions, but I’ve got a bunch to learn, so i figure the more I learn on here, the fewer mistakes I make out during my precious track time!
one more as well:
Does not idling mean the fuel is essentially cut off when the driver is out of the gas? Would that be potentially more harmful at the end of a long straight when a new driver gets out of the gas and coasts for a few seconds thereby starving the engine of any lubrication at all?
Should a new driver who coasts a lot have a higher idle speed to prevent this, or should said new driver just learn to drive before he blows up his motor?
Actually 2 cycle engines are slow to return to idle. In racing situations, it really never totally cuts off as there is so much fuel in the bottom end, it keeps running. If it set to idle, it just take longer. The clutch doesn’t have time to disengage. Remember, in racing situations, you are either on the gas or on the brakes, never coasting.
We warm ours on the stand using the brakes to load the engine. Just revving the engine on the stand does little, same as driving slowly around the track. Always get the engine to 100 deg minimum before getting rowdy. The Rotax runs a bit warmer than other engines. We have one that will not run below 135. 135 to 145 seems to be the sweet spot for most Rotaxs. This time of year its a bit of a challenge to get them warm and time consuming. You don’t want to rev and load them much but I’ve seen temps at start up of 52. You have to gently rev them till they get in the 70 80 range, then start loading them and working the throttle to get them up to 100. Then it still seems that you have to drive with your arm over the rad to get them warm enough to have fun. Plenty of tape helps.
The problem of fuel cutoff at the end of a straight is more a problem of air, too much of it, not fuel or lack of it. It a problem a new driver shouldn’t even worry about as he won’t be pushing his motor hard enough on the straight for it to be even a remote problem.
Just warm it up before geting silly and drive the crap out of it.
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