Bike seems to run funny, maybe just me

android86 · Jun 15, 2003

i know this has been posted alot but i was i just bought my kdx. Its a 2003. Im not sure whats wrong with it or if there even is something wrong. The bike fouls plugs every 30-40 miles. There is wet spooge coming from the exhaust tip. And when I am in like 1st or 2nd gear (mostly in 1st) and even when its in neutral and i twist the throtte. it seems to start to run rough at a certain point when the rpms get high enough. It happens mostly when im cruising down a trail in like 1st gear and i try to accelerate more it seems to sputter and run funny. This may be just the way they run but i know my dads 76 two stroke doesn't do this. It just keeps revving higher the more you get on the gas. It has plenty of snap and power and never bogs down. I have heard that the kdx runs rich in stock condition. I have read the carb tuning section many times but im not sure if it even needs tuning. I live in RI so i guess im pretty close to sea level and the temp. is usually 60 -90 when i ride.Does it sound like i need to tune it. Oh, and will drilling the airbox give you more air in the mixture at every throttle position. Will this do any additional harm. Sorry its so long but thanx for your help. I love this site it is very helpful.

jboomer · Jun 15, 2003

It does sound like it's running rich. Pilot probably and especially the needle. If you've read the JustKDX site about how to jet, then you'll remember the section about performing a plug chop. You really need to do this in order to get the proper feel for what's going on. Yes, drilling the airbox will allow more air in and lean the mixture throughout. If you're going to perform this mod (which I'm sure is HIGHLY recommended) then do it before rejetting. If you do it after you rejet, then you'll more than likely need to rejet again. There will be plenty more replies after this one, this is a very popular site and those KDX guys are borderline FANATICS about their bikes, so stand-by!

davidg · Jun 15, 2003

Besides modifing your air box lid, check your air screw. My bike had it set a bit rich from the shop. Turning it out (1/8 turn at a time) will help lean out the pilot jet. You can also consider raising the clip on your needle one spot. You might need to buy some jets, do a plug chop and see what works best for you. Good luck!

CaptainObvious · Jun 15, 2003

My bike runs funny too. It makes me laugh everytime I reide it!

jboomer · Jun 15, 2003

Tighten those engine mounts RV! It's a KDX not a Harley! If it's still ticklin your feet, try an extra pair of socks!

android86 · Jun 15, 2003

i have reset the idle screw from the stock setting. I just set the screw low enough so it wouldn't stall at idle. But the bike ran wierd like this and when the setting was stock. Will the air box mod do any harm to the bike. How big and how many holes should i drill in it.

android86 · Jun 16, 2003

will doing this make it to lean

Zerotact · Jun 16, 2003

Yes, removing the airbox lid allows more air to flow in and will lean the bike out a bit. My stock 220 has the airbox completely removed, and the airscrew is out 1 1/2 turns, and it stopped spraying oil out the back.... I have yet to ride it like this, but next time i get a chance.

canyncarvr · Jun 16, 2003

Adjusting the air screw on a stock jetted kdx is pretty much a waste of time.

'Does it sound like i need to tune it'

You need to rejet it, yes.

'..it seems to sputter and run funny..'

It's four-stroking (firing every other time). Seeing as it's a two-stroke (fires every time), that's what makes it 'funny'.

Oh...it's not supposed to do that. Maybe some on a choke-cold start..but not otherwise.

I'm not clear on how you could read the info on CDave's site and still have a question on whether or not you need to change some stuff...

But you do.

Follow the recommendations on CDave's site and you'll be much better off.

cfr1970 · Jun 16, 2003

First of all, Android, the screw you need to adjust is the AIR screw, not the IDLE. You will definitely want to completely remove the airbox lid. Some drill holes because they don't want to re-locate the regulator. (black box on top of the lid) If you decide to drill holes, as many as possible is a good start. I've never owned a new KDX, but to my understanding, the rejetting is almost a pre-requisite. If you plan on putting on a new pipe, you will have to re-jet again. If your parts guy is anything like mine, you can just even trade your jets. (This puts a lot of miles on the car running back and forth, but cheaper than buying a boxload of jets) That should get you going.

By the way, jboomer, what do you mean BORDERLINE fanatics? :aj:

jboomer · Jun 16, 2003

:laugh:

canyncarvr · Jun 17, 2003

Don't know how I missed the 'idle screw part'. I like to rag on folks about that! ;)

btw, the idle screw is black/nylon. The air screw is brass, on the updraft side near the fuel bowl.

And, not that it matters much...but the box on top of the air lid on 'H' models (what android has) is the CDI unit (note all the wires). Note the unit attached to the brace behind the airbox. The unit with two wires going to it? That's the VR.

Whatever it is or what you call it, it's not hard to relocate. Use either a tie-wrap, drill/tap your own hole or use an existing tapped hole.

Bike seems to run funny, maybe just me

android86

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Bike seems to run funny, maybe just me

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