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Revo not idling down

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vgibbens

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I need some help figuring out why my Revo will not idle down. It will start OK when cold. When it does fire up, the idle starts high and remains high. No matter how the idle screw is set, it will not idle down. I've checked for air leaks, replaced the fuel line. I just changed the exhaust coupler. In addition to the idling problem, the temp is getting way too high, close to 300. All needles have been set to factory numerous times. Oh yeah, the problem has been there since the first tank. I had it running really well the other day following Rolex's tuning advice on various other threads, but as always, as soon as it warms up I have the idle and high temp problems. On the occasional chance that the idle does settle down, the temps are only 220-230.
 
vgibbens said:
I need some help figuring out why my Revo will not idle down. It will start OK when cold. When it does fire up, the idle starts high and remains high. No matter how the idle screw is set, it will not idle down. I've checked for air leaks, replaced the fuel line. I just changed the exhaust coupler. In addition to the idling problem, the temp is getting way too high, close to 300. All needles have been set to factory numerous times. Oh yeah, the problem has been there since the first tank. I had it running really well the other day following Rolex's tuning advice on various other threads, but as always, as soon as it warms up I have the idle and high temp problems. On the occasional chance that the idle does settle down, the temps are only 220-230.
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Have you adjusted the carb opening as well when the engine is off?Have you checked to see any debris in the carb , needles?
 
When your at an idle is your wheels moving??? we need more info man
 
Since it sounds like occasionally the idle WILL settle down, that's every indication of an air leak somewhere. Check your tank and the lines, and seal the carb neck and backplate with red RTV silicone.
 
I've had the same high temp problems since tank one also. I just got a new carb body because the threads for the end cap were stripped out and I thought that might be the cause for an air leak. I think I may have bigger problems though and you might check this on yours also. I noticed that when I turn the flywheel by hand I could hear air leaking. I took off the header and when the piston goes up you can see bubbles in the after run oil (between the piston and sleeve) as compression builds. I'm pretty new at this but that does not seem right. Hopefully somebody here can answer that for sure.
 
bashaholic said:
I took off the header and when the piston goes up you can see bubbles in the after run oil (between the piston and sleeve) as compression builds. I'm pretty new at this but that does not seem right. Hopefully somebody here can answer that for sure.
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That's normal. When it's moving slowly, there's enough time for the compression to get by. At a high RPM, it's too fast for seepage.
 
Thanks Rolex, I thought for sure I had a bad fit between the piston and sleeve.
 
Sorry, i've been away for a few days. All the throttle linkage was checked, fuel lines replaced. I've had two different "nitro guys" at the LHS looking at it. Teh LHS worked on it for about an hour and a half yesterday. Since the problem's been there out of the box, the LHS is sending the motor back to Traxxas. There is still the problem with the clutch always staying engaged when it warms up, this is also when I have the idling problem.
 
Another tiny possibility...have you checked to make sure the throttle trim on the transmitter isn't advanced causing the carb to stay open even when you close the idle stop screw?
 
Candyman said:
Another tiny possibility...have you checked to make sure the throttle trim on the transmitter isn't advanced causing the carb to stay open even when you close the idle stop screw?
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Yes, I've made sure. I was following Rolex's advice on turning, requiring the trim to be turned all the way to the left. That, and we followed Traxxas' tuning directions. Thanks for the suggestion though.
 
vgibbens said:
the LHS is sending the motor back to Traxxas. There is still the problem with the clutch always staying engaged when it warms up, this is also when I have the idling problem.
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Hallo, what is new? Do you have the engine back from the Traxxas? What the clutch? The problem with engaged clutch when warmed up is solved?
 
yeah, you could say it's solved. I bought an O.S. 0.18TM while I was waiting for my motor to come back from Traxxas. After I broke the .18 in, I found a faulty O-ring on the tank, eventhough it was checked like three times. I ended up replacing all of the fuel tubing again, and replaced the tank. I've not had any issues since. I sold my 2.5R to the guy at the LHS when it came back. I'm thinking the clutch issue was bearings. I ended up replacing them as well when I went to the 15/36 gearing.
 

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