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1994 CR125 Rev When Starting

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Hi. My CR125 uncontrollably revs upon starting. This is with the choke on or off, and throttle blips do not help. It is also pouring gas out of the breather tubes with the bike off. I am assuming it is the float, but a second opinion would be appreciated. It has a Keihin PJ 36 carb. Also, how much would a carb rebuild be at a shop if I already have the parts?

Thanks

Dylan

:thumbsup:

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Maybe you should take the carb off and clean it real good and set the float level right. It sounds like a lean condition on start up. Maybe a clogged pilot jet or something.

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Maybe you should take the carb off and clean it real good and set the float level right. It sounds like a lean condition on start up. Maybe a clogged pilot jet or something.

Thanks. I forgot to add that my spark plugs look good at a 36:1 with Amsoil Interceptor.

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http://www.thumpertalk.com/forum/showthread.php?t=976095

I ended up having to pull the carb apart, and found what looked like a bit of sawdust in the needle valve.

I didn't ride my bike for a long time once and had gas coming out the vent. I looked inside and there was a dead spider in the float valve. I don't know how he got in there.

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It's hard to say but it's easy to do and a good place to start.

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I didn't ride my bike for a long time once and had gas coming out the vent. I looked inside and there was a dead spider in the float valve. I don't know how he got in there.

The itsy bitsy spider climbed up the petrol spout!

Anyway, to the OP, fix the overflowing issue first and then start on the revving buzz. At least that gets 1 problem out of the way.

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Would doing that fix my rev problem, or will I have to rejet?

Revving on startup like that has nothing to do with jetting. First thing's first, clean the carb and make sure the float height is set right. A rebuild kit is not a bad idea and they're easy to do, no need to take it to a shop. If that doesn't fix things up, then you might have a bad left side crank seal.

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Revving on startup like that has nothing to do with jetting. First thing's first, clean the carb and make sure the float height is set right. A rebuild kit is not a bad idea and they're easy to do, no need to take it to a shop. If that doesn't fix things up, then you might have a bad left side crank seal.

Is there some kind of cleaner used when rebuilding?

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You can use carb cleaner, I always use wd40 and blow jets and passages out with compressed air.

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KX250's rev on startup. I use the choke to throttle the RPM's so you're not revving a cold engine. It's completely normal on a KX, not sure about your honda though.

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KX250's rev on startup. I use the choke to throttle the RPM's so you're not revving a cold engine. It's completely normal on a KX, not sure about your honda though.

It doesn't just idle high. The engine uncontrollably screams.

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It doesn't just idle high. The engine uncontrollably screams.

Yeah, it's a lean condition. Probobly sounds somewhere around 1/2 thottle or so.

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did you happen to have the top of your carb off before you tried to start it.

I have seen people put a slide in backwards. That makes for a interesting start up

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did you happen to have the top of your carb off before you tried to start it.

I have seen people put a slide in backwards. That makes for a interesting start up

No. I was riding last weekend, and it only revved on startup occasionally. I think I'll take the carb into a shop. They can rebuild it for $50+ parts.

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