Does covering the air box help at all (Choking)

i see a lot of the top 2 stroke guys covering their air box im wondering if that helps and if so how does it help

I don’t see folks covering airbox in race on current engines. In pits, to get a recalcitrant engine to turn over, yes.

I think that leaning-out of the engine pre corner was a thing of the direct drive era. Not sure it has any useful effect on current 2 strokes.

3 Likes

Most of the time you see the drivers "choking"or rich up the engine at the end of a straight and at the end of a race,just to protect the engine from seizing.
This was very common in with the rotary valve engines (20.000 rpm)and later reed valve engines,what Dom Callan just mentioned.

2 Likes

Ha I got it wrong. I assumed that impeding airflow would impede the fuel aspiration, thus “Lean”.

I got this backwards, yes?

1 Like

It’s a technique called choking… More info on that here:

Probably not needed with the lower RPM/Output 100cc’s of today. But it looks cool.
With reeds you have to be careful not to overdo it or you can break (and then ingest) the reed petals.

2 Likes

This is mainly why I do it.

5 Likes

They still race with the direct drive high rpm 100cc.
In Italy there is a competition in this class,most of them are the older star drivers from back in the days but I saw Alessio competing with his dad Alessandro Piccini
at the Lonato track.I love the sound of the rpm’s,but 15 min on a piston that’ll cost you a lot of money for a race weekend!

1 Like

No need to airbox choke any of our 2-stroke engines here anymore. Choking it to start it is common though.

1 Like

Well,actually you can see it more often in de OK class,pistons last 30 min when driven by the top drivers,when they are ahead like 2 or 3 sec in the last lap most of them tend to choke.

1 Like

Right, but we don’t have OK here in the States.

1 Like

Yeah difference between a KA100 and an OK is pretty big. With the KA Being aircooled you could nearly argue the reverse.

One practical application in KA and the other 100cc air cooled engines is you could use it as a way to cool off the engine in a draft/slipstream. Useful if you’re staying behind for a while, sizing up your opponent.

KZ you’re stuck with whatever jet is in there for the race so it makes sense to give it a dab of choke if you feel it’s on the edge.

2 Likes

How many rpm’s do the Iame KA engines?

1 Like

i don’t know maybe 15k

15k or so for Junior, up to 16-17k for Senior.

2 Likes