KDXRIDER.NET

Just bought a 96 KDX 200 that's all stock. The previous owner told me it didn't run very well and hence I got it for a very good price.

Here's the problem - the bike won't idle. I've got the throttle stop all the way in. Also won't pull cleanly to redline. It's obviously loading up and rich (black spooge and fouling plugs), but I can't seem to figure out why.

Here's what I've done and checked so far -

Drained fuel tank and mixed fresh gas with yamalube R @ 32:1

Cleaned carb. Checked pilot and main jet for blockage. Checked all the circuits with carb cleaner to make sure they were clear.

New float needle and seat

Checked floats - they still float

Main jet - 155
Pilot jet - 42
Needle clip - middle slot
Air screw - 2 1/2 turns out
Float height - 16mm
Compression - 150psi

New NGK BR8ES (several )

Cleaned the air filter.

Checked for cracks around intake boot. Sprayed WD-40 around with bike running, but no change in RPM to indicate an air leak

Pulled the flywheel cover to see if there was evidence of a crankshaft seal leak, but I don't see any black stuff there. I don't appear to be losing any transmission oil either.

Looking through previous posts, it appears I'm pretty close on the jetting. I started jetting down on the main jet today just to see what would happen. The bike ran a little better for every size down I went. When I got to a 138 the bike pulled cleanly through to redline. I'm sure if I go with a smaller pilot jet, I'll get it to idle. I'm afraid I'm headed down the wrong road by jetting that far down. A 138 main jet seems to small to me. I suspect I would just be covering up a problem. I'd rather fix it correctly.

I've exhausted my knowledge. Anyone have an idea?

Had that problem with my brothers when I built it. Turned out to be a clogged Pilot Jet..... replace it and see if that makes a difference....

Sounds like a very weak spark to me. CDI box problem is what I suspect based upon your symptoms. You know someone with a KDX to swap out the box with for a "test" confirmation??

P.S. Check out coil/plug wire/ plug cap and associated wiring and grounding paths also to confirm they are within specs and tight.

IdahoCharley wrote:Sounds like a very weak spark to me. CDI box problem is what I suspect based upon your symptoms. You know someone with a KDX to swap out the box with for a "test" confirmation??

P.S. Check out coil/plug wire/ plug cap and associated wiring and grounding paths also to confirm they are within specs and tight.

While I don't know anyone with a KDX 200, I do have a buddy with a KDX 220. So you gave me an idea. I swapped the carb from his 220. It fired right up, idled, and ran great. So, I guess the problem is with my carb.
Now the question is what? I've replaced my float needle and cleaned the carb really good. I was able to blow carb cleaner through all the circuits. Guess I'll go back and do it again.

Indawoods - I know the pilot is not clogged as I can see through it. However, I guess it's possible there's some gunk in there I can't see that's restricting it. My buddy's 220 carb is running the same 42 pilot that I am. I think I'll swap just the pilot and see if that helps.

Thanks for the suggestions/ideas guys.

ZACTLY.... same with my brothers....

I rebuilt his 3 times before I found some green crap in the pilot jet... I just replaced it vs trying to get it all cleaned out and possibly having the issue again.

Well, new 42 pilot didn't work. Guess I'll try and find a 40 to see if that helps.

I checked the choke to see if it was possibly leaking fuel by, but that's not it either.

I don't know what else to do short of finding another carb on eBay.

Of course, I could switch carbs with my buddies 220 and hope he didn't notice

Something is hallared, wallered or plugged....

Just get an Air Stryker from Ron at http://rb-designs.com

Then you be talkin!

New RB carb would be great as in the long run you'll want RB's work anyway. Can get used carb on ebay, or maybe send him yours and let him look it over. Soaking the carb in Berryman's/hitting w/ air hose might do the trick as well.

Thanks for the replies, I'm going to check out RB's carb tonight. I looked last night on eBay, but didn't see anything.

Why don't you send your current carb to ron? I'm sure he can fix if if anyone can, plus, you can get all the RB magic.

IC is familiar with carb idle/adjustment problems. He found a speck of flashing crud in a lo-speed passage. That sort of thing will pass carb cleaner all day.

You're familiar with the line-up required for the needle nut cable retainer?

Get some guitar string clippings. Soak the carb in some Berrymans. Poke and prod the passages you can get to with those string ends. Soak some more, blow it out...al better.

...hopefully.

Looking forward to what you find!

What about the "tower" that holds the jets and is held down by the tamper-proof star screws? I've read in several places not to mess with it, but if it's removeable then it's got to have some sort of gasket under there.

I don't think the gasket that is under there is a replaceable part. Ron might be able to let you know if it is.

Ron adjusts jet block height on older Keihins to match newer styles to make needles/clipping common between the two, so it's not like once it comes out it never goes back in.

..don't know what sort of sealing piece it has..an o-ring?

I'd wonder about the more common carbie problems before I'd invent new ones.

I'd follow CC advice if I were you and Inda's advice if you have a small PJ plugged.

The tamper proof star screw can be removed (appropriate star wrenchs available at Auto Zone and Checker stores). I took mine apart 2 or 3 times and just reused the o-ring. Removing the nozzle piece gives you better access to a couple of internal passages.

Berrymans!

Hey Mr. Wibbens,

Could ya spin that can o' Berrymans around so's I can read the label and see what the heck it is?

No but here's the MSDS
http://www.berrymanproducts.com/Portals ... 200905.pdf

Hey Thanks!

That's a gruesome 'brew'

Why is that the stuff that actually works also kills you in the nastiest ways?