Throttle sticking

jriley43

jriley43

New member
Last weekend I went riding with a few friends of mine. Anytime I went through a whoop section or hit a rocky section at mid throttle or higher my throttle would get stuck open. Each time it did it I would pull the clutch in and romp on the throttle, which would free up my throttle. I have taken my carb. out to see if maybe the slide was sticking on something, but have not found anything that would cause it to get stuck. Also checked the throttle cable, and it was working properly. (I went ahead and oiled the cable) Is there something else that I am missing that would give me this problem.
 
Broken slide return spring? Cable frayed inside the housing? Pulley binding in the throttle housing?
 
Depending on the cable routing - you can also have the cable pull out of the adjuster and hang up on it. Safety wire cable to adjusters at each end of throttle cable to avoid this issue.

jeff
 
Check the routing first since its the easiest. Give a yank on the cable and see if anything happens and make sure there is some slack. I stuck a bottle of water behind my headlight once and it caused it to rev up out of control.
 
What was the outside air temp. and humidity ? Carbs. can ice up when the air temp. is above freezing.
Wrapping the carb. in bubble wrap, or something, is a quick fix for cold weather riding. Even better is to channel warm air from the engine.
 
Last edited:
GMP said:
Needle jamming in nozzle from sand/dirt in float bowl. It doesn't take much.
Click to expand...

I'd go with this one .. my 06 300 had a bad habit of going wfo through whoops if I had gone through deep water before hand. It did this two or three times on me. Take alook at your slide and see if you notice and scoring or scratches. Take a look at the needle same deal. My slide had a few scratches but my needle had evidence of much more. Put filter kit from kevins racing on your carb vent lines.

http://www.kevinscycleracing.com/

click carb/intake on menu on the left
 
Mine will do that occassionally when going over whoops or bumps .

May look into those filters.
 
biggstr6 said:
Mine will do that occassionally when going over whoops or bumps .

May look into those filters.
Click to expand...

There was a huge thread about this on KTM Talk as well and the common theme was it happened ALLOT when going over whoops (yup, me to). No solid answers but it sure seems to me there is something else going on here besides dirt and grit in the carb. Freaking scary when it happens.

All above advice is good though and can only help lessen the problem.
 
I've had a throttle stick twice, both on a KTM300 EXC with the same PWK38AS carb as my three GG250s. Once was unquestionably attributed to the throttle cable becoming snagged on my damper mount. The second time was from sandy water being aspirated up the vent lines during a deep puddle crossing in south Jersey. A post event trail side carb disassembly showed sand in the bowl and a needle with vertical scratches. Cleaned carb, no more water crossings, no more problems.

Since then, two things I do now to a new bike before even riding it are check the cable routing and install a longer cable if things are even close, saftey wiring it in.. Yes I do it to the GGs as I think the cable is too short unless that changed since '07. Second is split the vent lines and run the filters. No more problems, and I have run a lot of south Jersey enduros over the last ten years which are sand whoop fests more often than not. This is all based on the PWK Air Stryker, which I'd guess there are a lot in service. Now, if these instances are all from bikes with the new Air Stryker II, perhaps there is something to it, but I'd rule out the basic potential causes first.
 
Brian VT said:
What was the outside air temp. and humidity ? Carbs. can ice up when the air temp. is above freezing.
Wrapping the carb. in bubble wrap, or something, is a quick fix for cold weather riding. Even better is to channel warm air from the engine.
Click to expand...

The temps did get below freezing at night and in the mourning, they got cold enough to freeze up my pump on the keg that we had, but it would get in the 40s during the day.
 
jriley43 said:
The temps did get below freezing at night and in the mourning, they got cold enough to freeze up my pump on the keg that we had, but it would get in the 40s during the day.
Click to expand...
That could do it. Especially if the humidity was high. The air in the venturi is colder than the outside air. I think a carb. can make ice at 40F+ under the right conditions.
 
Any New information on this topic?

Last autumn my Godson had his 2002 EC200 scream (high RPM) itself to death. He noticed that its throttle revved / stuck while going over whoops. He was playing in a big mud puddle/pond prior, but the issues stopped after he left the whoops. Then he went back to the mud pond and the throttle stuck wide open and it would not stop. He was soaked and the single wire kill switch was shocking him so much he could not press it to kill it. He ultimately pulled the gas line to stop it but it melted the top end and crank bearings.

I inspected the bike immediately after the melt down and the throttle was fine. I rebuilt the entire engine but never found a cause. The crank seals were fine, the intake gaskets were fine, the throttle cable was fine. The carb to intake boot had some minor dry cracking but none went all the way through, but I replaced it anyway.

I checked the carb float bowl and it was clean. I did not have one of the Motion Pro cables with the threaded ends so I applied a little JB weld epoxy to the cable sheath end to secure the sheath in the throttle adjuster screw. I drove the bike for a few miles over some hills and trails but no whoops and it ran great!

The first ride for the rebuit ec200 was a local enduro. The first mile of the enduro had a whoops section. My Godson's father was riding the 200 this time and was lagging behind so I waited for him to see what was up. He told me that the bike went wide open on the whoops. I was shocked. I spent several minutes to double check the throttle cable and it was still rigidly secure at both ends and the cable sheath was routed correctly. It was not binding and the throttle worked perfectly.

I started the bike and it rode fine across the flat corn field. I normally ride a big bore XC300 and the 200 runs well but it is not an unmanageable amount of power. I took it on the same whoops section again and I was riding with a constant 1/3rd to 1/2 throttle in 3rd gear. The bike acted normal for the first three whoops and all of a sudden the bike the bike went WFO and shot out from between my legs and looped itself down the trial in front of me like it was possessed by a nitrous demon (well ok.... maybe a baby nitrous demon). I did not open the throttle to WOT (where it could get stuck) it went WOT on its own.

I just got through riding it hard across the field and the engine did not have the same amount of power I just witnessed on the whoops.

Entertaining side note- My friend was standing 200 ft away watching the event. When he came over to help, I could not help myself so I told him, " I don't know what you are talking about. The bike runs fine!" I was wearing my GoPro and the video is rather interesting.

Again the throttle, cable and ends were fine. Prior to the whoops section the bike had not seen water for 8 months.

I started thinking that maybe the bumps caused enough force to bounce the slide up so I am going to replace the throttle spring but I think that is wishful thinking.

The bike runs well normally and I think the jetting is pretty close, but I wonder if this event could be related to the carb being a little rich in the 1/3 to 1/2throttle range and if it went leaner over the bumps and had a surge of power.

Another possible option may be that the float level is slightly low and it could similarly cause it to go lean over bumps.

I have not found a good answer for this event and I would appreciate your thoughts.
 
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Not sure if this has been mentioned in other posts, but my 2013 went WOT a couple of times on a weekend trip.
Got home and cleaned carb and replaced cable.
Rode last Sunday, same thing happened, and I bailed out of the ride.
Rechecked tonight and examined the white plastic collar at the end of the Spring.
I hadn't noticed it had a small "tang" that sits in the groove of the nut that holds the needle.
Re seated this and hopefully this cures the problem...
 
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