Stuck Throttle - Need Help

[CR Kevin]

Hello fellow moto junkies - I need assistance with a throttle problem on a '96 CR 250. I crashed very hard at an MX track today as a result of the throttle getting stuck wide open. Fortunately I did not get injured, however, needless to say I went home after the crash (not confident with the bike in this condition).

Prior to the crash, all throttle components were clean and well lubed; in fact, I replaced the cable with a Motion Pro Cable approximately 6 rides ago. That too was well lubed and kink free (also routed correctly to the carb). The throttle snapped back hard and smoothly as it should. Today's problem seemed to come out of nowhere. Anyhow, I have disassembled and inspected all components and cannot locate the culprit.

The throttle assembly (on the bars) appears to be the original from '96 so as a result, I am considering replacing the entire throttle assembly. Anyone have any recommendations? I saw a Motion Pro Vortex complete throttle assembly offered through Chapparal Motorsports for approx $28 - anyone have any experience with these? Alternatively, I could buy a new Honda unit and perhaps also purchase a Works Connection or Moose Aluminum Throttle Tube for the handlebar. They run approximately $49 each and I would assume are worth the $$. Finally, the spring in the carb appears to be in good shape - do they wear out?

Finally, is it possible that the slide assembly in the carb could simply be worn out after nine years of use. It appears groove and scratch free and in very good condition. I am considering polishing the slide with a fine emory cloth, is that a wise idea? This could be followed by a high speed polish. Lastly, the one area where I did see some wear was on the actual handlebar (under the throttle tube). It is a Moose offroad aluminum bar, there were fine grooves worn into the bar itself. What is the best way to clean this up - perhaps emory cloth or 200 grit or higher sandpaper??

Any and all advice and recommendations are very much appreciated. Really want to get this fixed correctly as a 250 two stroke that randomly sticks wide open is extremely dangerous. Thanks very much in advance!

[mxerncolo]

Kevin,

Before going to all that trouble, make sure the cable is not binding by the ignition between the upper and lower triple clamp. I saw a guy having fits the other day w/ an '02 CR250, and this was the problem. Duct tape took care of it until he could get a new cable.
jim

[cowboyona426]

I have one word of advice from you- take your business somewhere other than Chaparral (Craparral). They have TERRIBLE customer service from my experience. Sounds like you've done your homework... Go over the assembly again with a fine tooth comb. You might try unhooking the throttle cable from the throttle and pulling it with pliers to see if the problem actually is in the throttle or elsewhere. I had my throttle stick one time on my Suzuki DS 80- I was rampaging out of control everywhere, managed to stop, and my Grandpa (fearless leader) heard the engine racing, wiggled the throttle cable a little, and the problem went away and never came back... don't ask what made it stick. Good luck finding the problem.

[OlSchoolFool393]

I don't think you need to buy any thing you most likely just have a problem with the cable binding some place.
(GLAD YOUR NOT HURT)
Just take it all back apart and check it closely for something not being put together properly,Don't get mad at Me for this it's
just what I would do ?
Why did You change the cable in the first place was it a problem
like this allready there?

[CR Kevin]

Guys, thanks for all the input; it is appreciated. Cowboyona, thanks for the scoop on Chapparal, never actually bought anything from there before. Ol School, in answer to your question, I did have a problem previously and that is why I changed the cable. The problem went away after the replacement of the cable but appears to be back. All parts are soaking in solvent as we speak so they are completely clean. What is the best lube to use in the actual throttle assembly itself??? I'm thinking not white lithium grease as this stuff could restrict movement - any suggestions?

Mxerncolo - how is the moto out in CO? I've snowboarded quite a bit out there but didn't know it had a moto scene. Thanks for the tip on cable routing, I'll check that out.

[OlSchoolFool393]

I always use something lite like pb blaster or maybe wd 40
Good luck sticky throttles are never good!!!

[Jeff172]

Check your needle. A bent needle can do this.

[psyklone393]

that's a good point, i didn't even think about the needle but that would definitely do it.

-Z

[CR Kevin]

Jeff - good point, I'll check the needle, maybe it is slightly tweeked. Never thought about that being a potential cause for the stuck throttle.

[cr-manp4l]

if i remmeber right ur throttle cable goes over ur number plate bolt and down the left side of ur plate and i rem u saying that u had moose bars and i know that moose bars are wider then normal bars so my suggestion is to run it under the bolt due to ur throttle assembly is farther away i had to do this on my dads 250

[CR Kevin]

Thanks pingers - that is a good suggestion, the Moose bars are wider than stock. Anyone reccomend an aluminum throttle tube or are they not necessary? They run about $50 vs. $15 for a stock plastic one.

[cr-manp4l]

i wouldnt really suggest a alumium one but if u are going to spend the money u might want to get a needle bearing one but that is my suggestion

[mxerncolo]

[i]
Mxerncolo - how is the moto out in CO? I've snowboarded quite a bit out there but didn't know it had a moto scene. Thanks for the tip on cable routing, I'll check that out. [/B]

I was surprised when I moved out here. There's 5 - 6 maintained tracks w/in an hour. With something like 330+ days of sunshine, it's an awesome place to ride.

[Only registered and activated users can see links. ]

jim

[CR Kevin]

***Purchased a Keihin 38MM PWK Airstriker***After listening to everyone's suggestions and very carefully going over all potential stuck throttle candidates, I have determined that the chrome plating on the slide is worn beyond it's limit as is the bore in the carburetor - it appears that was the reason for my sporatic stuck throttle syndrome.

Anyhow, real excited to ride with this new carb, I have heard nothing but great things. It will be installed this weekend. Anyone add a 38MM PWK to a CR250? The dealer I bought it from recommended using graphite powder in the throttle assembly and also on the plastic throttle tube. Does anyone think that is a good idea or have experience with using graphite powder?? I know to stay away from White Lithium or WD-40. Any and all suggestions are appreciated.

MXerncolorado - the website re CO MX looked really good, glad you have a strong Moto scene out there. I'm in NY where finding a place to ride is getting increasingly difficult.

[Mr.Boof]

cant a dirty carberator do this also?

[brokenbones]

On my bike the throttle tube used stick a little, the problem was just dirt. I cleaned it really well and used some emory (sp) cloth (re. sandpaper) to take the garbage off the handlebars. I have not had any problems since. I did not lube it with anything. If your grips are trashed dirt can get into the tube and gum things up. If you do lube it, I would think a dry lube like graphite would be a good choice but like I said, if it is clean in there you shouldn't have any troubles.

[dirt__rider]

ya boof a piece of dirt could hold the slide open. Happend the other day to my neighbors trike.