KLX110 Air Box

I've been hearing alot about opening up the airbox on the klx110. I drilled some holes in the upper portion prior to passing through the filter. I do not recomend this. The engine flutters when given throttle and dosen't idle well. I was going to jet the carb up, but after talking to Powroll, I learned that the stock airbox actually has the best overall performance on the dyno. There are other mods for the air cleaner, such as a K&N air filter, but bottom end is sacrificed for more top end.


Powroll is full of it. The stock air box is far from the best thing out there. I use a foam air filter right on the carb. Just clears the front fender. That's the way to go if you want to open up the intake.

How do I know? Becuase I played around with opening up the stock airbox.

How do you open up the stock airbox? Here's how:

1. Remove both the left and right tank shrouds.

2. You'll see there's a small rubber snorkel that runs from the airbox through the frame. You can only see this if you remove the airbox.

3. Open up the removed airbox. Bolt the back half of the airbox to the frame.

4. Take a marking instrument and go to the right side of the bike.

5. Look at the square hole in the gusset(s). There's a gusset on the right side and left side. Take your market and mark the outline of the square hole onto the back side of the airbox through the square hole.

6. Take a Dremel tool and cut out that square.

7. Now your airbox is opened up properly.

The only reason to keep the stock airbox is that when you wash the bike you won't get the air filter wet.

Riding the bike in the mud won't affect a foam air filter as you might think. The fender catches all the mud.

When you wash the bike, you simply was the air filter, which should be done anyway. Now the air is super easy to get to (with a foam filter).

The reason your bike doesn't run good is the jetting is all off. With the airbox opened up you have to rejet the bike.

My son's bike has the foam air filter, and no choke at all! Not only that, I removed the choke butterfly from the carb, and epoxied up the holes.

This bike literally starts first kit every time!

I've already articulated the mods, and with these mods, I run a 85 jet.

You'll need probably a 82 jet at a minimum.

The bike should idle perfectly.

Good luck,



Check out the air filter! Dirty after 3 track sessions, but it flows great still!


Hi Tony,

Thanks for the input. I've been reading some of your other messages. I went out today and ordered an 85 main jet. Nobody has them in stock! Did you do anything with the pilot jet? How many shims did you place under the needle? I know your son's bike is built so the jetting is going to be different than mine, I'm just jetting an idea. Also, I've been considering Powroll or Fast 50's for engine mods. I take it you would recommend Pitboss over both these companies? Where did you get your triple clamps?

Thanks for any info you can give me.


I have removed the shims, and have only the 85 main jet in there. I've corrected the off idle with the air adjustment.

With the bike the way it is, the jetting is perfect. Once you open up the pipe and airbox or foam air filter, you'll be running pretty much like me. The higher compression won't throw off the jetting nearly as much as opening up the intake/exhaust.

I hate to say this publicly, but I was shocked at Powrolls response to the questions I asked of them (which is why I won't buy from them, nor will I recommend them):

Q. What are the specifications on the cam you sell?

A. I don't know the specs.

Q. What do you mean you don't know? You won't give it to me or you didn't design the cam?

A. We don't have any idea of the specifications of the cam.

Q. If you don't have the specifications of the cam, how do you know that the valve-to-piston clearance is, and how can you build a motor around the cam?

A. We don't know the specifications. We have had no complaints and we've run the cam in a ton of bikes with no clearance issues.

Q. Ok. Could you get the specifications of the cam if you had to? I'm looking to build up a engine and need those specs so I can get my valve sizes and port volume/velocity correct.

A. No.

Q. OK. Can you build me a engine that makes 12HP+?

A. No. Impossible.

Q. What do you mean impossible? The ports in the head and the valve sized combined with the relatively low peak horsepower rpm indicates that there's a lot of power to be found through head work and rpms.

A. Good luck. To get 12HP+ you better have a good dyno operator (implying that my dyno operator would tweak the dyno to show more HP than there really is).

At this point I just hung up the phone.

The tone of the conversation was one of "We don't care if you bring us your business. We don't have any idea of any of the specifics of the products we sell, but that doesn't matter because we're Powroll".

Well not only does the tone & attitude bother me, but the total lack of information about their products indicates that they could care less about the possibility of a valve hitting a piston, that they have no liability, etc..

In any event, Powroll doesn't make the piston or rings in their kit, nor do they make or have they designed the cam they sell. You can get the same piston kit at many places including PitBossRacing.

I've had several sources with personal experience utilizing their cam that it pretty much sucks. I've not tried it so I can't comment (I would have it their attitude and service didn't suck so bad). But in the end I'm glad I didn't.

In any event, I've gotten personally involved in building a motor that will product the 12+HP needed to make the bike competitive.

What you'll be seeing soon is a custom ported head with custom tuliped titanium valves (unshrouded), custom springs, titanium retainers, reshaped combustion chambers, custom intake, and larger flat-slide carb, all using the PitBoss cam.

So if think you might be interested in one of these cam/heads, you need to get the correct piston. For that you'll have to go to PitBossRacing.

If you think that you just want to do the big bore kit and leave it at that, then there should be no problem going to Powroll (or any place else including PitBossRacing).

BTW, the billet tripple clamps are from PitBossRacing.

Sorry the long post.. but those guys sorta pissed me off :-)

Good luck,


Tanks Tony,

I haven't decided how far I want to go with the engine yet. We do alot a desert riding and I need reliability. Its a long walk back to the truck when your miles out in the desert. I think I'll give Pitboss a call when I get ready to do more mods. I'm very interested in their suspension though. I thinking maybe I'll get the air box and pipe squared away and then do the suspension before going any farther with the engine.

Thanks again Tony.



If you plan to do the suspension, you better order the forks now! I had to wait a long time to get them. The forks are 2002 KX60 forks and list for about $300 for the pair new from Kawasaki complete. Just slide them in. You'll also want to order the stiffest spring that Kawasaki makes for the forks as the KLX110 is a lot heavier than the KX60. I've also added a 5/8" shim on top of the fork springs to get the bike to set correctly. They are about perfect now.

If you get the PitBoss rear suspension, you'll have to do the forks otherwise the bike will sit pointed very downward which will screw up the rake angle and the bike stability etc, as the rear end sits taller due to the increase in travel.

The bike when you're done like mine will site just a tad taller than the 2003 KX65.

Engine stuff:

You might also consider the port work that PAX Racing does. They did a nice job on my head. Nothing major, just a little port reshaping, valve unshrouding. This has a very positive effect on the midrange of the bike, as well as comlementing the increase in compression ratio. It doesn't cost a lot, and won't hurt the reliability.

I would also recommend getting stiffer clutch springs. They are inexpensive, easy to install, and will eliminate the clutch slippage. You have clutch slippage now. It only gets worse when you up the power. This is bad for the life of the clutch. The clutch springs will eliminate the slippage. I think they run about $20


Thanks Tony,

This suspession sounds great. I'll be looking into this soon. The engine work sound good too. I'm still considering a big bore kit, but want to keep the compression down 12:1 or below.

Thanks again.

Mike Hawkins.


FYI... with respect to the compression ratio:

At 10.5:1 - 12:1 compresson ratio will still require race gas.

I think the approximate limit is around 10.5:1 on pump gas, on a carburated motor.

The stock motor is 9.5:1

The rule of thumb is that for every point you increase your compression ratio, you increase your HP by 1%, thus making a jump from 9.5 to say 10.5 would only yeild about a .06 hp difference which isn't worth the hassle/cost.

at 13.1, you're getting 3 1/2 points, which translates into 3.5% increase in HP which equals .21HP increase 1/5HP.

At least that's the accepted rule of thumb. I've not dynoed before and after so I could prove/disprove it :-)


if i only have an open filter no other mods do i have to re-jet the carb?(2008 klx110) im not at high elevation. if i do what jes size do you guys recomend.


some say you have to, other say you won't have to.

I just took mine off and it seems to run fine in the garage, still haven't gotten it out in the backyard :/

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