We have been messing around with my son’s Coleman CT200U. Recently replaced the carb and air filter. After replacing, the engine won’t return to idle. When you let off the throttle, for some reason the top plastic part on the carb (don’t know what it is called) won’t close all the way, causing the engine to not slow down to idle. Do I need to adjust and/or lubricate something? My son rides it pretty hard and it is definitely dirty. Any advice for a novice dad would be much appreciated!
Black plastic piece at top of carb won’t close all the way
- Thread starter Stevebainu
- Start date
Hi Robert. Thank you for the reply. Yes, we did put the linkages back in the same holes. Everything was working well for a while. Then we noticed it was idling high, tried to adjust the idle screw. That is when we noticed that the carb did not appear to be closing all of the way. I am going to try cleaning it up a bit and lubricating some pieces to see if that will help. Any other suggestions are much appreciated!
Hello Steve. Check if the linkage is bent that would make the movement shorter. Sometime when the throttle cable can actually bend the linkage. Or the linkage may be upside down or backwards. Look for ware marks at each end of the linkage. Sometimes when the engine running the vibration causes the linkage to slightly “twist “ and causing jamming. Another test is to remove the linkage,start the engine, and use your finger to “give it gas”. If it doesn’t idle down on it’s own there might be something wrong with the carburetor it’s self. Hopefully this helps or at least narrows down the checklist of possible problems.
Thank you everyone for your ideas. After some testing, it appears that the linkage is the problem. When we open the throttle and then let it go, the linkage does not return the carb to idle. Does anyone have any thoughts as to how to deal with a stuck linkage? I have loosened the bolt that was recommended but that doesn’t help. I have also tried shooting some lubricant under the gas tank by the throttle mechanism but still no luck. Any thoughts? Thanks!
Hello ....Good pictures would help. Test each part of the system to see if each part moves smoothly. The throttle cable, cable end,all levers, linkage etc. or disconnect the cable with the rest linkage still connected and test. Hard to tell which part(s) is binding. With out seeing it. Last resort is to add a spring to help force it shut. Make sure the spring runs parallel with the linkage movement so nothing gets bent or bind. Tony
Hello again. Try adding little paint or whiteout at each connection of linkage let it dry. With engine off throttle it open and shut ( manually close it fully) a couple dozen times. You should see paint scratches or chips everywhere the mechanism is binding. A small mirror can be used to look behind or under the pieces of linkage
Is the throttle assembly completely stock or did you make changes to it? Have you loosened the throttle cable to verify that the manual linkage completely returns to the idle position when moved to idle by hand?
If you have the stock air box you should remove the filter and top part of it to see what's going on while troubleshooting. And troubleshoot with the chain off or the back tire off the ground.
You should also understand how it works. When the engine is off the throttle shaft on the carb (black plastic piece) should be appx 75% away from the plastic idle screw. When you start the engine and open the choke the governor is responsible for moving the throttle shaft on the carb to idle. With the manual throttle at an idle position the governor can easily overcome the minimal spring tension of the throttle spring. The throttle spring is very loose not doing much at idle.
With the engine off can you easily move the governor rod that is connected to throttle on the carb to the idle position up against the plastic idle screw? Is the tiny spring also connected to the carb?
What is stopping the governor from moving the throttle on the carb to idle?
If you have the stock air box you should remove the filter and top part of it to see what's going on while troubleshooting. And troubleshoot with the chain off or the back tire off the ground.
You should also understand how it works. When the engine is off the throttle shaft on the carb (black plastic piece) should be appx 75% away from the plastic idle screw. When you start the engine and open the choke the governor is responsible for moving the throttle shaft on the carb to idle. With the manual throttle at an idle position the governor can easily overcome the minimal spring tension of the throttle spring. The throttle spring is very loose not doing much at idle.
With the engine off can you easily move the governor rod that is connected to throttle on the carb to the idle position up against the plastic idle screw? Is the tiny spring also connected to the carb?
What is stopping the governor from moving the throttle on the carb to idle?
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