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Thread: ct70 misses after it warms up

  1. #1
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    ct70 misses after it warms up

    I have a 2004 widfire ct70 . there is not 200 miles on it . it looks as new . I know the battery is dead, and I have a new one ordered. last fall it was running fine then it started to act up right before winter, I noticed that the plug wire had hit the exhaust pipe and appeared to have just melted the outside cover. I just put a plug wire splice kit on it and replaced the plug . the bike will start and run just fine for about 5 minutes , then it starts to miss and backfire and will stall out. it does start right back up , but still runs the same . . when the engine cools off it will run fine for a few minutes then does the same thing .. I had the carb off and checked the inlet screen and inside the float bowl, the appear as new, no dirt . could my carb be plugged up ?

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    Quote Originally Posted by veizter View Post
    I have a 2004 widfire ct70 . there is not 200 miles on it . it looks as new . I know the battery is dead, and I have a new one ordered. last fall it was running fine then it started to act up right before winter, I noticed that the plug wire had hit the exhaust pipe and appeared to have just melted the outside cover. I just put a plug wire splice kit on it and replaced the plug . the bike will start and run just fine for about 5 minutes , then it starts to miss and backfire and will stall out. it does start right back up , but still runs the same . . when the engine cools off it will run fine for a few minutes then does the same thing .. I had the carb off and checked the inlet screen and inside the float bowl, the appear as new, no dirt . could my carb be plugged up ?
    See if the fuel tank cap vents are plugged - trapping a fuel tank vacuum. This can prevent fuel from leaving the tank. You can clean the tank cap in lacquer cleaner to clear the vents but this stuff is obviously very harsh around paint so use caution. It is also highly flammable . . . be careful.

    Also, run the bike hard until it quits and then IMMEDIATELY, I mean RIGHT NOW, close the fuel tank valve to off. Then open the drain screw at the bottom of the float bowl and see how much fuel comes out. If only a little comes out, then you have a clogged fuel line, float valve or some other stoppage in your carb.

    Have you checked the valve clearances? I'm guessing this is a CDI ignition - no points - - not much to check there. How about engine timing?

    Rick
    1970 Chevrolet El Camino (under deconstruction)
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    runs bad

    Quote Originally Posted by veizter View Post
    I have a 2004 widfire ct70 . there is not 200 miles on it . it looks as new . I know the battery is dead, and I have a new one ordered. last fall it was running fine then it started to act up right before winter, I noticed that the plug wire had hit the exhaust pipe and appeared to have just melted the outside cover. I just put a plug wire splice kit on it and replaced the plug . the bike will start and run just fine for about 5 minutes , then it starts to miss and backfire and will stall out. it does start right back up , but still runs the same . . when the engine cools off it will run fine for a few minutes then does the same thing .. I had the carb off and checked the inlet screen and inside the float bowl, the appear as new, no dirt . could my carb be plugged up ?
    I can get the bike to run, it will run for a minute or two , then it gets super hot and dies .what can make it run hot ? i have two of these bikes, i have switched the carbs and it made no difference. any ideas ?

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    Running very hot is a lean condition symptom. B52's suggestion is checking a lean fuel delivery that shows up after a few minutes.

  5. #5
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    Doubt it's a plugged gas cap.I'm with ez on this,lean condition.Check your plug and if it's bone white your clone's jetting is way lean.They are notorious for that.Post up a plug pic and a carb pic and or tell us what carb it has.What pilot jet #s and main jet#s are in the carb?Start with your clip adjustment to the richest setting and if thats no help a bigger pilot/main is the way to go.
    Last edited by OLD CT; 10-28-2012 at 01:03 PM.
    Aim high! The Clinton foundation

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    I bought a restored CT70 and it ran when I was buying it but wouldn't start when I got home. The spark plug wire was also all melted as it was too long and laying on the exhaust pipe. Once I rerouted it, it started right up. I ended up just cutting the extra off and soldering the wires together and taping it up.

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    How do you do the clip adjustment? That's inside the carb slide, right?

  8. #8
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    Correct. The lower the clip is set, the richer the setting.

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