Due to some life events (going self-employed, 2 children needing brain surgeries, fun stuff like that), my 2007 KLX has been sitting in the shed for quite some time. I rode it once last year and that was to get it inspected and registered. Bike died on me about a mile from my house, so I pushed it the rest of the way and there it sat. Yeah... Life got very busy...

So I took it out the other day, put in a new battery (old one wouldn't hold a charge) and fired it up. It took some starting fluid to get it going (not a habit I want to get into, I know), but it ran. Tooling around my 3 acre property, it ran ok, until I tried to get it past 5k rpm. At that, it promptly bogged down and almost died. Sputtered a bit, coughed up to 2k, then back down to barely running. This proceeded for a while. I was hoping it would, I dunno, run itself clean. Wishful thinking, I know...

It was obvious that I needed to get the fuel system completely cleaned out. I set out to remove the carb, clean it up, put it back in.



Yeah..it was really clogged up in there. Surprising it even ran, tbh. Anyways, I set to taking it apart and cleaning everything out really well. Every screw that could be removed, was. For the jets, I took caliper depth measurements and made sure they were installed back to the same depth, protrusion. The one exception was my main jet. I wrote down a value of .433" protrusion from carb face, but also noted that it was hard against the carb face. When I re-installed it, I snugged it against the carb surface and was puzzled by the measurement of .334". My first assumption is that I wrote the initial depth wrong....I tend to be dyslexic when I'm in a hurry

The main jet and jet holder were plugged up rather bad. Being a machinist (back to that "self-employed" comment), I do have my own set of very small gauge pins so I was able to poke out all the crud without doing any damage to the jets. (The main jet has a #128 on the bottom). Interestingly, the needle has 3 washers on it, and I've only seen mention of there needing to be 2 washers/spacers

Being careful with everything so as not to lose bits and pieces, I put it back together and got it into the bike after some head-scratching (they don't afford a lot of room).
All my fuel lines were cracked and broken at removal, so I replaced it with some clear fuel line from the motorcycle shop down the road. They are on the verge of kinking, so I've already ordered OEM molded hoses from partzilla.com

I was really pleased when it fired up almost right away. That quickly turned to sadness when I realized that the bike will not run past an idle speed. Any slight crack of the throttle and it dies. If I start it up with the throttle half open or so, it WILL rev up to that point, but there is a lot of "popping" from the exhaust and it can't stay running at that point. It will eventually just bog down and die.

Back to the drawing board. Problem is, I've not the slightest clue where to start and what to check. Looking for suggestions..


Bike modifications have been done by the prior owner (who is an automobile mechanic and was kind enough to include all OEM parts with the bike): Dynojet kit (which includes several different sizes of main jets, Air box cover removal, sprockets.

 

Looks like you have a lid of weed in your carb, was it from south of the border?

Sounds like a diaphram issue, did you boil the carb? With that much weed in your carb, it may reclogg unless you get all the passages cleaned out.

 

That's corrosion from the brass.
I took carb cleaner spray and shoved the nozzle down each passage that would fit and blasted away. Quite a bit of gunk came out

 

Clean the rats nest out of the filter box and replace the filter foam.

 

That was last year. Mouse made a home, pee'd everywhere and chewed the filter. Before I put it away last year, I dumped some mothballs in the airbox and left the seat off. No mouse nest over the winter

 

And nothing set up home in the exhaust (oh, that's a Two Brothers)

 

take off the rubber boot completely. watch the carb slide when you go to rev it, if its moving then you have a main jet clog or some other lack of fuel....check float bowl level.

if its not moving or not moving well you have a diaphram issue

 

Ooooohhh, I can run it without that boot and filter? Good to know for testing purposes (obviously not for anything more than testing)

 

Here are the findings: lightly rolling onto the throttle (barely increasing it, perhaps a few hundred rps at a time) the slide does NOT move. And then it dies.

Starting the bike with the throttle slightly elevated, perhaps around 2k, it starts and the slide is jumping up and down and raw fuel is getting spit out towards the air box

Starting the bike with the throttle set to "idle" (hand off the handlebar) it starts and idles. Rolling on the throttle and manually manipulating the slide and holding it in place, it runs somewhat decent.

Ok, so does this sound like the slide/diaphragm issue? I'll find a schematic, make sure I've got everything put together proper

 

Hmm... certainly could be. I think the tell tale is you said you can manually lift the slide and it runs somewhat decent....

That slide should come up smoothly and all the way up if you romp on the throttle. If you took the slide/diaphragm off make sure it doesnt have a hole/tear, and i prefer to put sticky grease around the recess to hold the diaphragm in place while putting it back together. My money is on some type of diaphragm seating or vacuum issue, meaning also could be a leak at the rubber flange between the carb and the motor. Something is leaking vacuum and not lifting the slide like it should (or slide is stuck, spring not installed correctly, etc.)

Another thing to check is that you put the needle jet/emulsion tube pieces back in right or didnt fall out, I think there was a thread recently about that exact thing and I think he had issues similar to yours.

Make sure the float level is staying full, make sure no clogs in fuel lines or petcock. If the fuel level gets low it will also cough and die when revving but run fine at idle.