Botched 3x3?

Bike's previous owner did this, which I have noticed doesn't match any of the 3x3 pictures I've seen. The preferred setup appears to be a square (duh) hole where the snorkel would have been, and the ignition stuff held out of the way with velcro or something. Correct? I've been searching and have read about 50/50 people saying the exact placement/dimensions of the hole do/don't matter. If this has any bearing on airbox recommendations I pulled the carb out to confirm the previous owner's setup. It's the TT FCRMX and is set up exactly as the FAQ recommends for my setup - Yoshimura RS2 with 96db spark arrestor, approximately sea level. Should I move and secure the ignition thing out of the way? Start over with a new airbox? Not change anything? Thanks for the help!



You have some bonus air flow with the square and round hole. If it was my bike, I would clean the square hole edges up, to prevent any plastic from being sucked in. Or purely for ascetics.

If the bike is running right, it is set up right. You will be a tiny bit leaner for a baseline, but jetting will be individual to each bike, elevation and weather.

the cdi box sits on stand offs and doesn't impede the flow of air,so no need to velcro anything.

replacing the airbox and starting over is the ultimate solution.

you could also glue a piece of plastic over the butchered hole and redo the 3x3 to the common jetting specs used on this board to make life easy.there's nothing to be gained at all on a stock motor by a bigger than 3x3 just forces you to run a larger main jet but doesn't produce more power.

If its running fine I wouldn't worry about it. If its bothering you, I personally would find a piece of plastic to match that hole. Get some epoxy or pliobond and seal it up and start over new.

If this were my bike.....

I'd cut a piece of thin aluminum, rtv and pop rivet it over that hole. Then I'd make a proper 3X3 where the snorkle would be. Or find a replacement airbox for cheap.

With the CDI sitting over the existing hole you have, it effectively covers much of it.

9 square inch hole(s), shape doesn't matter.

williams idea is good i think

thats possibly the worst ever 3x3 mod .lol

It's usually better if water runs down the rear of the airbox and out the drain instead of pouring on the filter into the engine.

should look like this;


I cut the entire top off my box. It would be ridiculous to seal it up just to move the hole.

Nothing wrong with a hole that is larger than prescribed. It just means your going to have to tweak your jetting a bit for the extra airflow.

Only reason everybody is so anal about the hole is because all the jetting recomendations on this site are based on that specific hole. Smaller or larger requires you to adjust your jetting on your own.

Leave your CDI on the pegs also.

If anything, it's a better design, lots of cool air flow around the CDI probably would mean longer life.

A follow-up, in case anybody with a similar question ever finds this in a search or something:

Just for peace of mind I bought another airbox, I think it was like $10 plus shipping on ebay. As a bonus it also came from an E model so it already had a proper 3x3 hole. Turns out the old setup really was restricting airflow because the bike is definitely stronger in the mid/high rev range now. I was surprised at the difference. I can also confirm, if anybody is wondering, that the E and S airboxes are identical except for the hole in the top. Swapping was more of a pain than I had expected, after some monkeying around I ended up unbolting the subframe to get enough space to yank the old one out and stuff the new one in.

Turns out the old setup really was restricting airflow because the bike is definitely stronger in the mid/high rev range now.

Your previous airbox was allowing too much airflow for your would have been running too lean ...

Your previous airbox was allowing too much airflow for your would have been running too lean ...

Hmmm, interesting. I assumed less airflow because of the CDI being in the way. I think both hole setups added up to about 9 sq in of "hole" just in different places. At any rate, it is better!

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