Reassembly wasn't too bad. The allen wrench in the back of the 8mm socket was definitely the way to go.


While I had everything apart, I started opening up the crankcase breather hole in the airbox. A very slow process by hand as I used larger and larger drill bits to work the hole open a little more each time.



So I thought I'd try a big lag screw with a large socket as a spacer. You all know what happens when you tighten something in plastic too hard-it strips out the plastic, right?

I bought a small bag of 3/8 OD lag screws, but wish I'd got one size larger.


Anyway, the lag screw idea worked well. Starting from the inside the airbox, I screwed it into that little hole (which I'd already enlarged a little), with the large socket acting as a spacer and stopping the screw from going in completely.

Then as you keep twisting, like a small drill bit the very coarse threads on the lag screw keep chewing away and churning out the bits of plastic.


A lo-tech technique for sure.

- I'll have a K&N breather on it after it arrives about 3 weeks from now, so the effort today with the lag screw was just something to hold me over until the crankcase breather stuff gets here.


I used a long extension with a universal joint to allow me to twist the lag screw easily.

 

I have done this mod on lots of bikes and 4 wheelers over the years and have found the results to be positive, it is usually done as part of numerous intake and exhaust mods so I can't say how much it helped any one aplication but as part of a collection of changes like venting the airbox, jetting changes, exhaust changes, in every case the engine I was working with was far more racy modified than they were stock. The KLX is no different.

 

Just because of the remote risk of a stray hot carbon bit, I'd leave the spark arrestor in any exhaust system I have. I would certainly hate to be that one in a million that caused a grass or forest fire because I wanted something for nothing in this case. It just isn't worth that hefty hundredth of a horsepower if I'm not closed course racing. You can say your bike doesn't shoot flames, but you never quite know now, do you.

That and I'd hate to be cited should I ever have the occasion to be inspected by a forest ranger if I was off road riding where I was required to have the spark arrestor, like the Wayne National Forest here in Ohio.

 

- Decades ago there was a hair dryer in the house that had a removable screen with a plastic ring that twisted into the inlet end, it went in on top of another screen that was built into the hair dryer.

You could definitely hear the rpms pick up when you removed the outer screen

 

On my KLX 250 I replaced it with a homemade snorkel and installed a K & N filter with excellent results.

KAWASAKI KLX250

KAWASAKI KLX250

KAWASAKI KLX250

 

I just added a K&N myself after de-screening.

I've just ordered the larger snorkel today which won't be here for a couple months, but I'm open to trying it without a cover at all once my extra jets arrive.

For now I am stuck with a 125 main and the OE 35 pilot with a shimmed needle at about 100 feet above sea level.

Needle shims for the OE non adjustable needle, the recommend Kawasaki needle with adjustable clip, and the KLX300 needle jet with extra air bleed holes are one their way as well. So I'll be going through and repeating the remove the carby ritual soon..

- I wonder if the lid on/lid off quandry is of primary importance only to those who still have a CV carb. The smallish opening in the lid may be part of the overall vacuum pulling up the carby slide chain of events.

 

In Europe, the KLX 250 is sold with electronic fuel injection,
the carburetor adapts automatically, without having to do tests with the jets.

 

It may be able to adapt to slight changes but there's quite a number of members here who seem to indicate that the fuel injections ability to adjust to any real power increases is negligible. FWIW

 

It 's true, but on a motorcycle carburetor mount a filter that increases the air flow
and increase the opening of the filter box as a racing exhaust already involves
having to work on the jets.

 

EFI by nature is not dependent on vacuum signal to deliver fuel into the venturi via jets exposed to the incoming air stream as there is in carbureted versions, It's preprogrammed.

Unless there's a vacuum sensor feeding info to something that would vary the amount of fuel injected, but I don't think there is on these bikes.


Taking the lid off and/or removing the screen could still lean the A/F mix outside of the parameters of the programmed EFI injected settings though of course.


Engines with any type of non-CV carby could still be somewhat dependent on any contribution the smallish opening the air box lid is making to how strong the vacuum signal/flow is over the jetting orifices in the floor of the carb.


Air scoop openings on race cars often have smallish openings in relation to the amount of power the engines are putting out.