Stuck Throttle

Well last Sunday coming around a corner i cracked the throttle to wide open and it stuck. I had to bail because the bike was heeded for a ditch. Bike launched itself and landed around 60-70 feet and went back to idle. When I got up i turned it of. My buddy's came back made sure i was ok. Then i had a buddy get the bike out for me. He said the throttle was hard to open twice and then was fine. I rode back to the truck maybe 15 miles and it never stuck again. I took it all apart today and can not fine anything wrong. The cable only has maybe 4-5 rides on it. I just redid the bike over the summer. I did noticed that the throttle tube is warring a grove into the housing. I will be cleaning the housing and do a better inspection tomorrow. What do you all think happened? I might just buy everything new just to be on the safe side. I have been riding for like 30 years and never had a throttle stick on me before. Some scary shit!!

 

BTW its a 06 yz250

Probably be hard to remember small details while it was going down, but.. Did you consciously turn the throttle off, or just let go of it? Reason I ask, if you turned the throttle forward (off) and the bike kept going, that would indicate something in the cable/slide. Otherwise it could have been some crud between the throttle tube and bar. if you're using full wrap handguards, stuff can work it's way in there and gum up the works. 

Yeah, it's scary shit for sure.

 

A milder case happened to me once. On my 295. Luckily I was going kinda slow at about 1/3 RPMs in 3rd gear. Some decent power but not really on the pipe and I used rear brake then kill switch to shut the motor down. In my case I pretty sure the problem was the throttle cable lifted out of the metal holder/cup on the carb end. So the throttle stuck about 10mm open.

 

Since that day, I've used rubber weld tape to seal that end of a new cable to the metal end piece. I also make sure I liberally lube the inside of a new cable, regardless of how slippery it's supposed to be. Lastly I'm paranoid about cable routing and slack.

 

OHB raises a good question too. Because the problem can be all up at the throttle tube. Some kind a wear, or binding in the pulley, or the tube. Having correct bearing function in that pulley is really important.

 

You've reminded me that my throttle system is in need of good clean, inspection, relube and possible cable replacement.

I just ordered every thing even the slide for piece of mind.

Do you have the little boot on the throttle cable secure at the carb end?  I had a KTM that kept sticking WFO and I found that the cable was pulling out of the seat at the carb end when the throttle is closed suddenly.  Now I safety wire the boot.

Do you have the little boot on the throttle cable secure at the carb end?  I had a KTM that kept sticking WFO and I found that the cable was pulling out of the seat at the carb end when the throttle is closed suddenly.  Now I safety wire the boot.

KTM has a different setup. YZ's throttle cable screws into the top of the carb. But thx for you suggestion.

Oh yeah, forgot about that.  Yamaha is smarter than KTM.

Oh yeah, forgot about that.  Yamaha is smarter than KTM.

:thumbsup:

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