New to me 1994 has bad stumble

fishwater · Post by **fishwater** » 09:55 pm Jan 23 2017

I just picked up a 1994 KDX200 yesterday. The bike sat for a few months & the previous owner drained the fuel, he put in a can of the premixed fuel & the bike started first kick. I went to check the bike out & it had a bit of stumble at part throttle but cleaned up nicely at half throttle on. Took the bike home & the stumble was still there so I took the carb apart. Inside of the carb is spotless, has what I think is factory jetting of 150 main & 48 pilot, float level looks spot on at 16mm. The bike is completely stock except for a Uni filter, still has the lid, snorkel, factory pipe & silencer. I'm NH at sea level & it was between 35-40 degrees today, it still has the can of premix gas from the hardware store. I'm thinking besides starting with a fresh batch of premix that maybe it was too cold today for the 150 main? Maybe I should bump it up a couple of steps? The bike starts on the first kick, a little choke when it's cold but sometimes doesn't even need choke.

doakley · Post by **doakley** » 11:43 pm Jan 23 2017

I would suggest you get the bike really warmed up thoroughly then see if the stumble is still there. And get it on some quality premix that is fresh.

Post by **KDXGarage** » 02:19 am Jan 24 2017

Welcome to the forums. Usually, letting it set for a few months ends up being a need for a carb cleaning.

fishwater · Post by **fishwater** » 07:28 am Jan 24 2017

Thanks guys, so it doesn't sound lean to anyone? It's cold but not as cold as our usual winter, I figured I'd want to go a little fatter in the main.

black · Post by **black** » 01:26 pm Jan 24 2017

a carb clean is simple and easy.... even the tiniest bit of crud in my xr650r causes issues.

fishwater · Post by **fishwater** » 06:39 pm Jan 24 2017

I also took the reeds out so I could peak inside & tore the gasket removing the base so I needed to order a new gasket. Figured I'd buy a couple of pilot & main jets as well as the bowl gasket. I've cleaned the carb & im waiting for the service manual I bought when I picked up the bike to verify the float level measurement.

fishwater · Post by **fishwater** » 06:48 pm Jan 26 2017

Service manual still hasn't come in but I put the carb back together & bumped the pilot jet up to a 50. Put in some fresh premix, replaced the plug & it's good to go, pulled cleanly through all the gears. I'm a little over 2 turns out on the air screw so the 48 was probably fine but I didn't like the way the inside felt when I was trying to clean it out so I replaced it with a new 50 that I ordered. Jetting isn't perfect yet but it's 45 degrees out & getting colder so I'm not riding anywhere soon, I have time to dial it in once it warms up.

fishwater · Post by **fishwater** » 12:33 pm Jan 27 2017

Well unfortunately all is not resolved. I ran the bike today & fuel is draining out of the vent. It's the vent from the bottom of the bowl & is worse when the bike is on the slidestand vs when I hold it perfectly upright. I measured the float a few times & the top of the float was at 16mm. I saw another image that stated to measure from the seam but when I tried that the float looked like it was at a really odd level. So any tips besides pulling the carb again? I tapped on the float bowl lightly a few times in case it was sticking but there was no change.

Also, fwiw this is a tough carb to pull, any tips to make it easier to snake out of the frame?

Post by **KDXGarage** » 01:13 pm Jan 27 2017

What is the condition of the needle valve that shuts off fuel flow? It is the rubber tipped cone that presses against the opening to shut off fuel flow into the bowl.

fishwater · Post by **fishwater** » 01:23 pm Jan 27 2017

Looked perfect, no damage, wear or disintegration. I sprayed carb cleaner down the seat but couldn't see anything obviously. I should have spent a little time cleaning the tip I guess but it looked perfect when I took it apart & I can't honestly say whether it was leaking or not before I pulled it apart.

fishwater · Post by **fishwater** » 01:26 pm Jan 27 2017

What else could it be though besides the needle & seat? Would the float height do the same thing? I'm thinking if it was float height it would leak from the other vents not the bowl one correct?

fishwater · Post by **fishwater** » 04:32 pm Jan 27 2017

OK, figured it out. The float was sticking because when I put the bowl on I didn't slide the vent tube through the slot next to the main jet, it went on but obviously the vent tube was causing the float to hang, doesn't take much!

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