Wide open throttle for no reason

Mike_Powell
Edited Date/Time 7/13/2015 10:44am
I have a 95 cr250r. Just fired it up and it idled for 2-3 seconds fine then went up to wide open throttle it seemed. The lever is working correct, the spring is good in the carb..... Any suggestions? Don't see any tears in the rubber coupler for the carb either
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Nathan180
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Nathan180 7/11/2015 2:05pm
7/11/2015 2:05pm
When is the last time you rebuilt the top end? When I had a hairline crack in the piston of my CR85, the bike would do the same thing. After I rebuilt the top end, it ran great.
Anthony Siracuse 7/11/2015 2:06pm
7/11/2015 2:06pm
Kind of unrelated but one time I had a bad clutch cable in my rm125 and the cable got stuck wide open and luckily I stayed calm and pulled in the clutch and killed the motor because it could have been bad.
Cygnus
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Cygnus 7/11/2015 2:08pm
7/11/2015 2:08pm
Look for an air leak on the intake and or around the engine gaskets.
Mike_Powell 7/11/2015 2:09pm
7/11/2015 2:09pm
I cleaned the carb last week completely. There is a new throttle handle on it as well. The slide is smooth and complete. I've never rebuilt the top end since I've owned it but I'd say there is maybe 20 hours since the previous owner did it.

The Shop

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jtiger12
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jtiger12 7/11/2015 2:17pm
7/11/2015 2:17pm
You got an air leak broseph. As cyg said check airboot and also check the spark plug
Old-Man
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Old-Man 7/11/2015 2:18pm
7/11/2015 2:18pm
Definitely suckin air, Check the intake manifold (Where the reeds are) make sure bolts are tight.
Tighten The bracket where the carb attaches to the manifold.



Or is it running out of gas?

nytsmaC
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nytsmaC 7/11/2015 2:28pm
7/11/2015 2:28pm
It just feels like it's going full throttle because of 2stroke. #powerbandz #braaap

Trade bikes with that guy with the KX450 who can't wheelie, 2 problems solved at once.
Mike_Powell 7/11/2015 2:30pm
7/11/2015 2:30pm
I'll check the bolts and plug. What about broken reeds, what would that do?
DPR250R
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DPR250R 7/11/2015 2:44pm
7/11/2015 2:44pm
Mike_Powell wrote:
I'll check the bolts and plug. What about broken reeds, what would that do?
Make it hard to start for one thing.
MaicoJC1
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MaicoJC1 7/11/2015 2:49pm
7/11/2015 2:49pm Edited Date/Time 7/11/2015 2:50pm
Since you said you just cleaned your carb and put a new throttle tube on on the bike make sure your cable is not getting hung up and re-inspect your carb to make surd that you didnt put it back together wrong...it happens sometimes.
Old-Man
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Old-Man 7/11/2015 2:52pm
7/11/2015 2:52pm
Mike_Powell wrote:
I'll check the bolts and plug. What about broken reeds, what would that do?
Depending on how bad they are it would be hard to start and if it does start it would run very badly.
They make the passage one-way like a heart valve in your body.... they prevent the power stroke from pushing air/fuel mixture out of the lower case back into the carbs
Frodad78
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Frodad78 7/11/2015 3:19pm
7/11/2015 3:19pm
Air leak or dirty pilot jet. Probably just the seal on either side of the carb since you just had it off.
Starcrossed
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Starcrossed 7/11/2015 4:46pm
7/11/2015 4:46pm
Spraying carb cleaner may help locate the leak. Short little puffs sprayed around the area in question. When you hit the spot you will hear it...with the engine running of course.
bvm111
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bvm111 7/11/2015 4:54pm
7/11/2015 4:54pm
nytsmaC wrote:
It just feels like it's going full throttle because of 2stroke. #powerbandz #braaap Trade bikes with that guy with the KX450 who can't wheelie, 2 problems...
It just feels like it's going full throttle because of 2stroke. #powerbandz #braaap

Trade bikes with that guy with the KX450 who can't wheelie, 2 problems solved at once.
WoohooWoohooTongueTongue
Eddie_E
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Eddie_E 7/11/2015 6:02pm
7/11/2015 6:02pm
check that you didn't put the throttle slide in 180 degrees out if it's a round slide. there is usually a thin groove for a pin on one side and a thicker one on the other side. if you flip it 180 degrees, it feels like the slide went down when you tighten the cap, but it's half open.
JB 19
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JB 19 7/11/2015 6:16pm
7/11/2015 6:16pm
nytsmaC wrote:
It just feels like it's going full throttle because of 2stroke. #powerbandz #braaap Trade bikes with that guy with the KX450 who can't wheelie, 2 problems...
It just feels like it's going full throttle because of 2stroke. #powerbandz #braaap

Trade bikes with that guy with the KX450 who can't wheelie, 2 problems solved at once.
Evil
mx317
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mx317 7/11/2015 6:23pm
7/11/2015 6:23pm
I had water in my gas one time and it would suck up to the main jet and lean out causing it to run wide open. I have a scar from it.
OldYZRider1
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OldYZRider1 7/11/2015 6:38pm
7/11/2015 6:38pm
Inadequate slack in the throttle or improper cable routing causing the throttle cable to be pulled when the handlebars are turned to the side? Been there, done that.

Hopefully something simple but if it's got several hours on the lower end, it's possible its pulling in air around the main seals. If so it may need a rebuild; a major repair requiring splitting the cases.

Pit Row

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gsxr6
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gsxr6 7/12/2015 12:22am
7/12/2015 12:22am
Last time I ran a bike out of gas it did this. I just pinned the throttle open, and the instant I did it stalled. Idk why I thought of it, but opening it wide shut that puppy right down( too lean to run).
gsxr6
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gsxr6 7/12/2015 12:25am
7/12/2015 12:25am
95 cr has a PJ( d slide) so impossibrew to install slide backwards if carb is the right, original carb.
RedDirtDog
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RedDirtDog 7/12/2015 12:41am
7/12/2015 12:41am
Anthony Siracuse wrote:
Kind of unrelated but one time I had a bad clutch cable in my rm125 and the cable got stuck wide open and luckily I stayed...
Kind of unrelated but one time I had a bad clutch cable in my rm125 and the cable got stuck wide open and luckily I stayed calm and pulled in the clutch and killed the motor because it could have been bad.
my friend had a 05kx125 that caught fire somehow, they rebuilt it and put all new plastics on. first time after the rebuild he starts it up, fires first kick and runs WFO and well he had'nt put the kill switch back on so hes panicing and decides to put the bike in 5th gear and drop the clutch in an attempt to stall it. which didnt work, he went flying into my fence laid the bike down and luckily it bogged out. I'll never forget the sound of that 125 starting up WFO. investigation led to a missing circlip that holds the throttle cable in the carb which got caught on the lip of the carb so it couldn't close.
Thelen20
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Thelen20 7/12/2015 1:06am
7/12/2015 1:06am
OldYZRider1 wrote:
Inadequate slack in the throttle or improper cable routing causing the throttle cable to be pulled when the handlebars are turned to the side? Been there...
Inadequate slack in the throttle or improper cable routing causing the throttle cable to be pulled when the handlebars are turned to the side? Been there, done that.

Hopefully something simple but if it's got several hours on the lower end, it's possible its pulling in air around the main seals. If so it may need a rebuild; a major repair requiring splitting the cases.
This is what I would look for since you just replaced the throttle tube, if there is no play in the throttle adjust the cable slack until you have a little play then start her up and see what she does
overthebars39 7/12/2015 1:10am
7/12/2015 1:10am
nytsmaC wrote:
It just feels like it's going full throttle because of 2stroke. #powerbandz #braaap Trade bikes with that guy with the KX450 who can't wheelie, 2 problems...
It just feels like it's going full throttle because of 2stroke. #powerbandz #braaap

Trade bikes with that guy with the KX450 who can't wheelie, 2 problems solved at once.
Just get this one

http://phoenix.craigslist.org/wvl/mcy/5116756594.html
hillbilly
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hillbilly 7/12/2015 6:32am
7/12/2015 6:32am
Mike_Powell wrote:
Thanks everyone for the awesome feedback! I really appreciate it.
why did you need to clean the carb? had the bike been sitting for a long period of time?

if that is the reason and the intake boot is good I would suspect the crank seal behind the flywheel

if the bike was running fine before your carb work it is something in your reassembly.
ToolMaker
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ToolMaker 7/12/2015 7:05am
7/12/2015 7:05am
Old-Man wrote:
Definitely suckin air, Check the intake manifold (Where the reeds are) make sure bolts are tight. Tighten The bracket where the carb attaches to the manifold...
Definitely suckin air, Check the intake manifold (Where the reeds are) make sure bolts are tight.
Tighten The bracket where the carb attaches to the manifold.



Or is it running out of gas?

My first thoughts too, ran out of gas.
Mike_Powell 7/12/2015 8:34am
7/12/2015 8:34am
The bike had been sitting for a while. The jets were clogged. After the reassembly last weekend, I started it and ran it for a few minutes. It idled perfect and the response was great. A week later is when it went balls out by itself! I'll pull the carb, check the jets, replace all the fuel and look for torn or open holes
DTHA70
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DTHA70 7/13/2015 10:44am
7/13/2015 10:44am
check reed/carb manifold seal, then dry side crank seal.

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