KDXRIDER.NET

Stats first:

2003 KDX200
Stock carb.
Needle: R1174, 3rd position
Main: 160
Pilot: 48
Plug: BR8ES, Gapped between 0.7 and 0.8mm
Vforce 3 Reeds
Fresh Gas: 40:1
Elevation: 600
Current Temp: 60

Back story:
I rode this bike for an hour in some sand pits, a lot of riding with throttle cranked, winding through gears. I never really just putted and the bike ran great.

2nd ride, I take the bike out to some woods following a quad. Slow lugging up and down hills. Bike stalled down hill. I thought it was out of gas, switched to reserve, rode some more. Then got some bog, like I was running out of gas. Took off the plug and it was pretty black and wet. Wiped it off and restarted the bike.

Brought it home and just tried putting around the yard. Choppy performance at first 1/8 of throttle when in first gear, just putting around. After 1/8 throttle bike wakes up and is great through the gears. I noticed the Air Screw was set at 3/4 out so I began doing some jetting research.

Here's what I did before doing any changes.

- New plug gapped between 0.7mm and 0.8.
- Fresh fuel mixed at 40:1
- Cleaned and reoiled air filter.
- Removed carb. disassembled, cleaned and replaced.

Issue:
I adjusted the AS and have gotten it pretty close. Definately a little better throttle response when blipping (RB term) it. In first it's stable and putts, 2nd and third too; a blip is responsive, no bog or stall. I thought I nailed it.

Then I let it sit there at ilde. Sounds nice, good rhythm, then at about 20-30 seconds of idle, irregular rhythm, quick rev up (1/2 second), and the bike stalls. The rev up is not me turning the throttle and its not fast just sounds like the bike's last ditch effort to stay started. I've played with the AS from 3/4 out to 2 out and keep getting the same results.

After this it takes a good 10-15 kicks to start. Sometimes I'll just leave it and come back and it starts in 5 or so. After the stall, the plug is a little wet, not saturated.

This is my first two stroke so I'm not an expert by any means.

Any ideas on where to start would be appreciated. The season starts in less than two weeks!

Be gentle with my jetting cherry! Well at least I hope it's jetting.

It sounds like a fuel delivery issue. Jets are clogged, pinched fuel line, petcock is clogged, vent line clogged.

Any rev up is fuel starvation.

Hmm, interesting... I'm on it. Pretty sure the jets are clean. I soaked them and made sure at least light would pass through them.

I run a guitar string through mine.... you'd be suprised some of the junk that I can get out of them....

Ok the gas flows from the fuel line pretty good, like it would empty in a few minutes... Not a dribble but a full stream. I got intimate with the bike and blew through the vent lines without problems.

Indawoods wrote:I run a guitar string through mine.... you'd be suprised some of the junk that I can get out of them....

First E string? Since it's an idle thing, it's the pilot circuit no?

A sticking slide or throttle cable at the very last mm of full close can cause the dying problem. I had this issue on my last ride last year...

I thought I had the idle set but what would happen is it would stick at the right position and after a while it would drop to where the idle screw was set and die. Took a while to figure that one out.

I am betting on the jets though....

What ever string fits... I always have snips of the whole set so I just use whatever fits best... Never a wound string though.

Try a different jet if you have any....

would the float level have anything to do with it ?

Yeah... those usually don't jump out of adjustment but if it is out of wack it could definately cause a fuel starvation problem.

1. OK, dropped the bowl and notice there was only enough fuel to fill the bolt hole where the main sits. Is this normal? I was expecting to see at least half a bowl of fuel. I did not run it with petcock on off the last time I ran it.

2. Removed the pilot, ran a guitar string through. Def made the hole a little bigger, nice! Put that sucker back in.

3. Let's check the main. Run the wire through it, clean it up. Reinstall, over tighten and snap it. Beautiful.

My day just got better.

What are my options? Learning the hard way here.

Options to get the brass threads out from the snapped main?

A very small EZ-out...

Check your float height too... that doesn't sound normal....

EZ-Out, figured... gettin' one-a-doze tomorrow.

Should I use the procedure in the manual? I dont have "Special Tool - Fuel Level Guage, M18 x 1.0: 57001-122"

Is there a tool-less man alternative?

Yeah... I use a little ruler I have ... it's real easy to measure if you turn the carb sideways and get the float so it just seats the needle valve and measure from the carb body....

Easier to show than to explain...

No, I get it. I'm referring to the service manual and I understand. I need a small metric ruler. 16mm +-2 right?

BTW, I went to the garage and took a look at the main, and I place a pointed tool I have in there and started turning and it came out! I knew I didn't over tighten it, rather I tweaked it anglewise. Ok, that's resolved.

So thinking about this I think both you (Inda) and Jaydollar are right; it's a fuel starvation problem based on the float level.

The manual says I shoudl bend the tang. The tang they are talking about is the little piece the float valve hangs from right?

For my knowledge: How much fuel should I expect in the bowl? Is the pilot ever submerged? There was no way enough gas in the bowl for the pilot to reach; there was barely enough for the main to grab some.

Yep.. a mil or 2 under helps stop the peeing you get... Mine is set at 17mm.....

Fixed???

Indawoods wrote:Yeah... I use a little ruler I have ... it's real easy to measure if you turn the carb sideways and get the float so it just seats the needle valve and measure from the carb body....

Easier to show than to explain...

This procedure isn't that easy. It's hard to trust the measurement when the float is so far away from the ruler. I'm not confident on just "eyeing" it. Plus, the floats aren't square and its hard to judge the height from the carb body. Any tips?

P.S.
Waiting on new main and pilot to be delivered.

The bottom of the float is square to the body of the carb when I measure.

Can you take a pic of what you are talking about?