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ninja machinist
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Discussion Starter #1
So I decided to fire up the dirtbike last Saturday and take it up and down the street. I've done this many times in the past. As I was about to put it away I gave it a little braaap and the throttle stuck wide open. I twisted the throttle tube closed but the motor stayed wide open. Gave me a pretty good scare to say the least. I did some searches online and figured the problem was probably due to a dirty carburetor. I'm not completely certain of this however. And from what I've read on other dirtbike forums there've been a few people who've had this happen. The fuckin bike is a death trap and I'll never be sure this won't ever happen again. My RC-51 has twice the power and I ride it on the street alongside cagers on their cell phones but this dirtbike scares the living shit outta me. Fuck.
 

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It's not a dirty carb. The cable and housing is probably pulling out of the ferrul at the top of the carb, resulting in it seeming like it's wide open even when
you close the throttle.

It should scare you. If you could stop it from looping out it will kill your RC51 in a drag race for a block.

You think that's mental, try a 2 stroke 500 MX bike. LOL.
 

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ninja machinist
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3,103 Posts
Discussion Starter #4
Yeah, those 500cc two-strokes sound pretty nuts. One of these days I'll go over my bike with a fine toothed comb. Until then I definitely will not be riding it.
 

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Ridin hard n dirty
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start from the throttle for smooth movement and work towards the carb...best case is cable is either pinched, frayed, or as mentioned not seated...then look at the carb for the needle coming loose, dirt in the carb holding the slide up...check the cable for enough free play, if it is too tight the throttle will open when you turn the bars one way...in most cases the throttle is rarely full open...just a 1/4 open will feel like full when you loose control..
 

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I like traffic cones :S
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I had that happen to my on my old 92 gsxr 750 while riding home. No amount of twisting shut it off. Clutch in, kill switch. rode home in high gear in case it did that again.

It was a throttle cable that was frayed inside.

time for a new cable. Might as well do the clutch at the same time. If one went the other is probably not too far behind.
 

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I had that happen to my on my old 92 gsxr 750 while riding home. No amount of twisting shut it off. Clutch in, kill switch. rode home in high gear in case it did that again.

It was a throttle cable that was frayed inside.

time for a new cable. Might as well do the clutch at the same time. If one went the other is probably not too far behind.
New throttle cable equals worn out clutch on dirtbike? What?
 

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I like traffic cones :S
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Im saying if one is messed up, the other might not be far behind since both probably had the same maintenance.

If ya gonna change one, might as well do both.
 

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When a two stroke is wide open the kill switch doesn't work . Either lock the brake or if the bike is on its side cover the exhaust with your glove. Note that's yet another of the thousand reasons you wear gloves dirtbiking.
 

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When a two stroke is wide open the kill switch doesn't work .
True that... I never thought of plugging the exhaust, pulling the sparkplug wire is a (really) jolting experience!

Once you're off the bike, the choices are limited, rear brake is tough to get to (and might not stop a big bore anyway), picking it up will get you dancing with a WFO bike and there isn't much time before the crank fails...

Thanks for the pipe plugging idea.
 

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ninja machinist
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Discussion Starter #17
So I took it apart yesterday. The cable adjuster just above the carb had broke and there was a tiny hole in the rubber boot around it. I figure a speck of dust got in and jammed the slide. Cable is completely fine.
 
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