KLX110 exhaust update

[westcoast]

I decide to try the Dr D exhaust to see how it compares to the stock set up with the 5/8" header mod. The Dr D exhaust is lighter, and the fit is perfect. The set header design uses the same OD for the header it self, but without any type of restrictor, unlike stock. The mid pipe is about .2" bigger in OD, than the header.

Performance wise, low end is good, although a tad less than the stock set up with the 5/8" mod. Mid range is comparable or may be a bit better than stock. The high end is better than I expected, with quicker acceleration at WOT. The only real down side is the noise level, at or near full throttle. As expected, the Dr D is louder that the stock pipe with the header mod.

But so far we only did a brief test in front of our house, we won't be able to ride until next weekend. I don't know if they make a quite core for the play bikes, but if they do that may be an option. The bike may also sound different at Gorman, at higher altitude and more open spaces. Temp wise it was warm out and that may have had an effect on noise as well.

The only change required was to open the air mix screw a .25 turns out. So it's easy to change out the pipe. Cost wise it's not the first mod I would do, but may be something after you have completed other suspension and performance tweaks. My son doesn't race, so more top end isn't the most important thing, but it's a nice to have.

[the Colorado Kings]

Pipe looks great. With improvements over a stock pipe on a stock engine, I think the performance gains of that pipe will improve if you ever do mods to the engine.

[westcoast]

Yeah your probably right, the pipe would help more with other engine mods. Only I think for the few trails we ride, the bike is fast enough for a 9 year old. Once football starts he won't have time to ride anyway, even now we don't ride as much as we use too. In another year, my son should be big enough to ride our TTR125LE, so I really don't want to put any more money into the KLX110.

[the Colorado Kings]

In another year, my son should be big enough to ride our TTR125LE, so I really don't want to put any more money into the KLX110.

LOL. I was thinking that as soon as my kids move out of their bikes (CRF50 and KLX110) I'll steal them and convert to pitbikes. They're just too much fun to hop on and ride. My daughter keeps eyeing her mom's TTR125LE, and I'm not sure how long it'll be before she takes it over. We may end up buying another TTR sometime. Great bike for smaller riders.

[westcoast]

Ryan,

I choose the Dr D because I wasn't planning on a big bore kit, just agreeing that if you did more mods, an after market pipe would work better than stock. Even though the header has the same OD as the stock pipe, the ID is much larger. Most exhaust that work well, include a step header pipe to save the low end, a bigger pipe would just hurt performance on a stock motor. The comment on the air mix screw was in addition to the 2 turns out I already had, so the air mix screw is now at 2.25 turns out.

[evil11]

what years your bike and where is the air screw on the bike i cant seem to find it on my friends 110 stupid stock carb cant even adjust the needle

[frankiewhipit]

I wouldn't buy the needle from 2 bros, it's a POS:thumbsdn: , shim the stock needle instead. As far as the air screw, remove it & cut a slot in it so you can use a small screwdriver

[frankiewhipit]

use a tiny washer under the clip, I dont see the need to lean it out, they're lean out of the box, opening the exhaust and/or air box mods should require a richer mixture

[westcoast]

You would shim the needle with a small washer or "shim" to lift the needle jet, and allow more fuel into the carb. Since most 4 strokes are a little lean to begin with, and airbox mods only make that condition worst, you almost never need to go the other way unless your bike is completely stock, and your riding in Denver at 6000 ft. You can find shims at radio shack, some dealers may give you a couple if you do enough business with their parts department.

Regarding the airmix screw, on a KLX110 it's actually more of a fuel mixture screw. Turning the screw out actually allows more fuel to go to the carb, not less because it is downstream of the throttle valve. Dr D under technical for the KLX110 actually recommends setting the screw to 3 turns out on a stock bike. I had already re-jetted due to my prior airbox and header mods, so the max idle speed was found at 2.25 turns out on our 110.

http://www.dubachracing.com/DubachRacing.html

[the Colorado Kings]

Here i just looked it up on the online fiche. It even says pilot/air screw. look at #16014

http://www.ronayers.com/fiche/400_0516/carburetor/carburetor.cfm?man=ka&groupid=6470&parent=6430

Kawasaki has been known to miss-label stuff. I'd be surprised if it was an air screw. As mentioned above, it's downstream of the throttle slide, which most of the time means it's a fuel mixture screw. Easiest way to tell without removing the carb is to phone a knowledgeable mechanic (ie TT Jetting expert) or just adjust it out and see if you get black smoke or a fouled carb. I had to adjust mine out after leaning it out with all the free mods, so my money is on the "out is richer" concept.

[westcoast]

The Kawasaki manual does label it as an airmix screw, which is way most people call it that. However, it does the opposite of an airmix screw, hence the clarification in my last post. Have you actually ever modified a 110 your self? If not you may want to try testing on your own, and then post your results.

Every mod that I have done on our KLX110 has resulted in obtaining the best performance and idle by opening up the fuel mixture screw. The stock setting is at 1.25 turns out with no mods, after minor mods most people have it set to about 2 turns out. If the mods make the bike leaner, and turning the screw out helps, may be it is a fuel screw.