Brain Power Needed! Any suggestions?

[SS109]

Today was... uhm... an eventful day.

I was so excited for the ride today. I spooned on some fresh tires, new grips, trying out a new air filter, along with my previous clutch actuator upgrade, and most importantly, my first real ride on my custom CDI.

I fire up the bike with everything set to base settings. Hmm, bike is acting funny. Try to rev it up and it wants to fall on it's face. I can only get it to barely move if I have the choke on even though it's warmed up. I'm thinking, great, I screwed something up with my CDI. I was instantly bummed. My buddy reassures me and suggests hooking up the OEM CDI to see if it is my CDI causing the issue. So I do and the same result. Crap. I think my float is sticking and beat on the carb for a few. No change. I tell them to go out without me and I'm going to try to figure this problem out.

So, while they are out I still can't figure out what is going on. Float bowl looks clean and can't see anything obvious. I remove the gas cap and that isn't problem. Petcock flows plenty. I finally give up and just sit down. Now what? I start looking up a carb rebuild kit and new float on Jets-R-Us. Have you seen how expensive these parts are getting? Ouch! Anyway, as I'm looking at the rebuild kit on their site it hits me after seeing the parts included in it, the needle clip. My needle clip felt a little lose last time I changed the needle position. So I unscrewed the top of the carb, pulled out the slide, and guess what? No needle! Eureka! The needle clip was still under the retainer at least. After fishing the needle out, and to salvage what I can of the day, I put the clip back on the needle and squeezed it with some needle nose pliers. It looked like it should hold for a ride so I reinstalled it and hooked my CDI back up. Bike now runs great so time to hit the trail.

I ran an 11 mile loop and, holy crap, this thing is pulling very hard from down low and was letting me lug a gear higher if I wanted to. Everything was going good and then, I got scared! Almost done with the loop and all of the sudden my throttle sticks WFO, the tire starts heading skyward, and I'm like "OH S***!" Luckily, I actually thought to use the clutch and kill switch to save myself. I just twisted it and all was fine again. Hmm, odd. Ok, finish out the trail then I'll try to figure out what is going on. Just as I'm finishing the trail it does it again! I get to the truck and think I must have gotten the throttle cable in a bind somewhere but don't see anything. I went to check the adjuster on the top of the carb and found the cable retainer section had broken off. Well...... crap! There were still some threads on it so I removed the broken off portion (about a 1/4" long piece) and screwed it back on. I had some excessive cable slack now but everything works so I thought all was finally good. Took my time to dial in my CDI, went out for another ride, and it stuck yet again! Ugh!

I'm at a loss right now. Maybe it's because I'm so tired or whatever but I have no clue at the moment what could be causing this. Anyone have any suggestions for me for when I'm more awake?

[John_S]

My guess would be that it’s missing that little C clip that goes through the cable adjusting barrel and holds the throttle cable in place. OEM part number 92036-018. It’s tough to tell on the carb parts page on rmatv but I think that’s the one. I would think if it wasn’t there you could gas it ok but then when you go to let off the cable housing “could” slide upwards toward the gas tank and then get hung up next time you throttle.

Just guessing here on what to check. I’d say new throttle cable, check to see if the white plastic ring that slides over the needle retainer bolt was slid down properly, new adjusting barrel and the C clip. I’d also remove the throttle tube and make sure that isn’t cracked on the cam side where it enters the housing.

If you haven’t pulled it apart yet, see if you can get it to stick again while it’s just sitting in the garage and then start looking near the piece that broke off to see what’s happening.

Glad you keep a finger on the clutch!!

[MoonStomper]

Nice save!!! I probably would have just pulled the ejection handle!

[SS109]

Thanks for the suggestions, John. All the parts are there including the cable retainer clip. The throttle cable isn't but a few years old but I am going to check it thoroughly. That's why it's confusing me, everything looks good. I do plan to try to recreate the problem here in the garage so we'll see what happens.

MoonStomper, yeah, I'm actually shocked my brain worked and I didn't just panic and crash!

[oldmankdx69]

Over the years of riding 3 different KDX's I have had that happen twice. Like you I looked and looked, replaced everything that looked suspect, and looked some more. Both times the chrome plated slide had a very small nick in it. Almost too small to see, but it was there. Not saying that is your issue but do not discount any small thing that could be causing your wild ride. Sticking throttles are not fun, I know. Good luck!!!

[SS109]

Thanks. I'll double check the slide very carefully.

[bufftester]

Had it happen 12 years ago, it was the event that led me to build my hybrid lol. Never did find the problem and never recurred. All good suggestions above to check the cable operation and routing, carb/slide. Perhaps the needle is catching and keeping the slide from returning? Very scary, but glad to hear you didn't have to "ride it out" lol.

[Slick_Nick]

Make sure the slide isn't coming up too far. If it does, it'll allow the needle to catch and stick it wide open. Check your throttle tube and mechanism to make sure they're not worn or broken.

[rungrandpa]

Happened to my son two days ago, it was the rubber grip pushed against the handlebar. He cut the end off out in the desert and that fixed it.
It happened on his Sherco a year ago. He could never figure it out. The cure was supposed to be a Motion Pro throttle assembly that uses two cables. I don't know much about it, but it was used on the bike that Sherco provided their pro to ride.

[John_S]

Reading through everyone’s suggestions I’m thinking the slide or the needle. First the clip came off the needle which would rarely happen then it’s sticking wide open. Nicks suggestion of it coming up too high and catching seems like a real possibility. Could that force of the needle hanging up caused the clip to come off? Roll the needle on a table just to make sure it’s not bent.

[MoonStomper]

Makes sense that you didn’t have an ‘event’ until after the needle clip issue. Your problem is likely there. If your slide is beat up though, definitely consider calling SUDCO for a #7 slide. Worked wonders for my low end throttle performance. If your needle is bent, try an 1173, that’s what Fredette gave me as his “preferred needle of choice”. I carry a new clip in my emergency kit, it’s one of those 3 cent parts that cost you a day’s riding when you lose or break one.

[SS109]

Man, some great suggestions! Thank you all! I will double check the needle when I get it apart. I have CEK needle as that is what Ron (RB) uses and I like it. Slide looks to be in really good condition but haven't inspected it super close yet. I have no clue what Ron cuts the slide to.

[Slick_Nick]

Man, some great suggestions! Thank you all! I will double check the needle when I get it apart. I have CEK needle as that is what Ron (RB) uses and I like it. Slide looks to be in really good condition but haven't inspected it super close yet. I have no clue what Ron cuts the slide to.

I think he cuts them to a 7. I still have my original data sheet from RB I’ll give it a look.

[SS109]

I think he cuts them to a 7. I still have my original data sheet from RB I’ll give it a look.

Cool!

[SS109]

Thought I should do a little update. Yesterday I tore in to the system. Tried to recreate the sticking with no luck so I decided to start pulling things apart. Carb looks good, needle is nice and straight, slide feels and looks great, and throttle assembly is good and free moving. The throttle cable feels good but it does have the smallest of kinks (and I do mean small!) right at were it goes in to the throttle cable holder on the carb. Not sure if that could be it or not. I'm going to inspect the carb and it's slide under a magnifying glass today to see if I find anything.

Anyway, unless my deep examination of the carb turns up something, I'm going to do a full carb rebuild using a Jets-R-Us genuine Keihin rebuild kit along with a new float, new jet block gasket (even though I did replace it about 5 years ago), and replacing the needle. Also going to install a new throttle cable just to be safe and servicing the throttle assembly to make it butter smooth. I pride myself on being the guy who's bike is never the issue on a big group ride so I tend to go just a little overkill solving any problem. Parts won't be here in time for this weekend so no riding for me or further testing of my CDI, sadly, until the following weekend.