Who here has removed the secondary throttle blade? I can't find a post here or anywhere that's specific to the KLX on how to do this.

On some other forums there's talk back and forth whether it's a good mod to do or not. What exactly happens when you remove it? Is it simply allowing more air getting in...or?

 

Secondary throttle blade? You mean the butterfly valve on the engine-side of the carb, down-flow of the slider? Remove it and I think your bike will run WOT throttle all the time. You won't need to twist that thing on the right handlebar. Should be fun!

 

Maybe it's an EFI thing. Not sure if there's a difference. On the EJK website under recommended settings they have one for:

"FMF Mega Bomb Full System
K&N air filter, secondary throttle blade removed, airbox snorkel removed, backfire screen removed"

 

^ That makes a lot more sense!!!
I didn't look at your location and just was thinking my carb'd model would be a challenge to ride without the butterfly valve.

If you find out more, post it up here for the lucky owners with EFI.

 

The secondary blade is usually controlled by the ecm to try and produce a flat torque curve. On the mega power 250 I dont think that it's going to have any real effect if it's there or not...

 

Don't really have any before & after hp figures but i'm sure the bike runs better without it IMHO! They are usually only fitted for smoothing out torque, emissions testing & noise control.

The diameter of the throttle body & the cams are the only real restrictions to tuning a EFI big bore bike, so taking out the secondary butterfly probably helps with better air flow & who knows what the ecm is actually doing to the butterfly at higher rpm's! Better out than in

Pretty easy to take out.

 

Thanks for that Joel.

From what I'm reading about other bikes, they say there's more power down low. Maybe only up to a certain RPM. (Some others saying different; power across the board) Probably depends on the bike and other factors.

Are you seeing more power down low or evenly across the whole power range, Joel?

 

Sorry just can't give you a definitive answer on that, as I took out the butterfly just after fitting a 331 big bore kit. The torque boost is night & day from a stock 250! I can't imagine my bike could run any smoother low down in the rev range with a butterfly fitted, so i'm happy it's out.

 

On a 250/300 it gives you instant throttle response at any RPM, and totally worth doing.

I had a Powercommander fuelcontroller, Q4 and Powerbomb, HiFlo air filter, no lid on my 2018 KLX250 and I felt I needed a 300CC jug.

I removed the secondary throttle plate, and the backfire screen, and installed one of my Kawazaki O2 deletes at the same time, and it transformed my bike, and the 250 is plenty for trails now, and the time delay hesitation is gone.. Turns out that Dynojet and Dobeck used to include an O2 delete for good reason.

 

I paired the secondary throttle plate delete mod with my primary throttle plate ECU control spring delete mod.





The Ecu delays closing the primary throttle plate which reduces engine braking, and also holds the plate open for that irritating manic fast cold idle. Simply removing that spring frees the primary throttle plate from ALL ECU controls. The engine still cold starts and runs just fine because the cold mixture is still rich, it simply idles at the same 1,500 rpms as when the engine is hot..


Try it, you might like it. If you don't, it's easily reversabie.



I live in a canyon so all the asphalt I ride on is twisted. Having instant deceleration engine braking from an instantly fully closed primary throttle plate is a great help in cornering.