Rev up your (KA) Engines!?

I was thinking about this as I drove to a customer today. What’s the proper protocol for warming up your KA engines?

Part 1
I’ve seen guys start it in the pits and just yank on the throttle and brake. Just making it scream.
Is this necessary? I’ve tried it, but I have no idea what it’s accomplishing.

Towards the end of the season I would start it in the pits and just give it a few gentle revs and keep it on low throttle for about 30 seconds. I never noticed a difference in performance.

Part 2
What’s the best way to kill the motor after warming it up? I usually cover the airbox as I don’t have the kill switch connected. This was suggested my many people to disable.

Does choking the airbox potentially lead to flooding the carb? I have noticed that it sometimes doesn’t start well on the grid after this.

I look forward to the responses!

The best is just to drive straight out the pits and take it easy one lap and just go for it. For water cooled engines just drive until temp comes up and go for it

I’ve never ever in my 19 year karting career warmed up an engine beforehand. We aren’t even allowed to do so in Sweden. But we are allowed to check if it starts for 5s

And yes you could kill via air box if you don’t have a working button.


Warming up is for water cooled engines.

Hammering the throttle on the stand and jamming the brakes is for warming up your brake pads.

The only reason to run it excessively on the stand it tuning the carb.

Choke killing it won’t hurt anything.


I was always under the impression warming up a motor is to help avoid a cold stick situation. The guys that are screaming the motors are likely just trying to clear out the chamber so when you start it again its good to go. If I have heat in the motor or its a warm day I don’t think you need much of a warm up if at all.

If you don’t have a kill switch there are only two other options, cover your airbox or pull the plug wire. Of the two the airbox would be my go to method.

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It’s worth considering that “cold” is relative too. If it’s 40/50’s in winter would dictate that whatever your process is… that it’s a bit longer than it might be at 100f ambient.

With the direct drive stuff I would sometimes fire up on the stand so I have a better chance of it starting on the ground.

I’m not a huge fan of free revving the nuts out of it without a load. I’ll load with the brake if for some reason I do need to get a load on the engine.

I prefer not to kill with choke as you’re drawing excess fuel into the crankcase that may cause a plug to foul on next startup. This can be exasperated by shutting down with choke before a period of laying up… the fuel evaporates and you’re left with the oil. Good for internals, bad for plugs.

Are these a good idea, well I guess that’s a matter of opinion :laughing:. Do what works for you.

The only reasons to start and run a KA on the stand is to confirm it starts and runs and to give it some brake and gas to warm the brakes up.

Its air-cooled, doesn’t need to be warm before you hit the track.

I don’t run a kill switch either and just choke the airbox to shut it off.

I try not to idle too much after running flat out to avoid flooding it and making it harder to start next time, so generally I’ll keep driving fairly spirited until the pit entry and then I shut it down and coast in.

Don’t overthink it.

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