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Discussion Starter #1
I have a cold blooded 2002 Honda CB 250 Nighthawk.
It will start every time with the choke on. I usually turn the choke off after 3 minutes and let it idle for another 7 minutes. It will do fine one flat roads, I can stop and go fine. When I stop on a hill though the revs will slow down and stall.

I have my foot on the back break, clutch in the friction zone, reving up to start to get a pull going, revs start to die down I apply more throttle, clutch is fully engaged the revs keep going down, i have the throttle pulled back pretty far still it will stall if I don't pull the clutch back in.

I come back from a ride and re-test on the same hill the engine doesn't even flinch and keeps going. I don't know what the problem is. I'm not very mechanically knowledgeable, I was hoping to get your guy's input.

If I don't let it warm up for 10-15 min it will stall or the beginning gives me a throttle delay and jerks the bike.

Would love to know what you guys think.
 

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Gone
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10 minutes should be plenty of time to warm up the engine. My best guess would be either a fouled plug or fuel mixture problem.

I'd try pulling the spark plugs right when this happens and see if they are fouled up.
 

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American Legion Rider
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Sounds like a potential vacuum leak to me. Metal expanding with heat and problem goes away.
 

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Discussion Starter #4
I've checked both of the spark plugs they look normal. How would I know of it's a vacume problem? Would I just have to take it to a mechanic?
 

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I personally think it's dangerous but spraying carburetor cleaner around the carb and intake. If it revs up you have a vacuum leak. Be sure to stay away from the hot exhaust though. There has got to be a better way but this does work but be careful where you spray that stuff. It's flammable.
 

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Discussion Starter #6
You were spot on, I sprayed some throttle body cleaner around the hosing connection of the carburetor and revs did go up. I think the seals need to be replaced, I'll go in and get the carburetor cleaned while i'm at it. Thanks for all your help, and quick reply. Really appreciate it.
 

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Great. We like hearing that. It still may not be 100% solution but you have to clear one item at a time for complete success. Let's just hope it is just one item.
 

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Pale Rider
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I've been told to use WD-40 for the same purpose. Don't know if it is flammable (I believe it is), but it won't damage rubber parts. Cheers!
 

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One somewhat safer way to test for vacuum leaks is if you have an oxy/acetylene torch, turn just the oxygen on very low (no flame) and use your torch tip to look for leaks. Same outcome, if there is a leak the revs will go up. Still have to be cautious as oxygen is as we all know very flammable, but it doesn't get all over the place and make a mess, and is a bit easier to pin point the leak. Just my 2 cents...
 
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