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Old 06-28-2008, 07:14 AM   #16
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Picco carbs tend to leak when they get heat soaked, the seam between the composite body and metal end bell tends to leak when the materials get warm... Simple fix and it makes a world of difference..

Thanks for the tip, is that just regular carb seal?

One thing I noticed with the engine/carb is that the tune is fine for about 3/4 of a tank of fuel, but once the fuel gets low it starts to lean bog on the bottom end, although the bog isn't too bad, just makes the car a little "jumpy" on the bottom. I know that any engine will lean a little when fuel gets low, so I tried to richen up the bottom, but then in won't idle when the tank is full?
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Old 06-28-2008, 07:19 AM   #17
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sounds more like a air leak in your tank to me...never had any of my engine run lean at a 1/4 tank of fuel. also out of 4 of the "older" styles that I have I have never had a issue with the carb and heat soak. and have ran 45 min mains before and always pulled off the track around 220
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Old 06-28-2008, 07:26 AM   #18
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sounds more like a air leak in your tank to me...never had any of my engine run lean at a 1/4 tank of fuel. also out of 4 of the "older" styles that I have I have never had a issue with the carb and heat soak. and have ran 45 min mains before and always pulled off the track around 220
Would an air leak in the fuel tank create the problem only when low on fuel or when the tank is full as well? When you say air leak in the tank do you mean around the nipple areas? I'm doubtfull that it's the tank because it's a brand new car, but I actually have a brand new spare tank, maybe I'll swap it out and see what happens?
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Old 06-28-2008, 08:09 AM   #19
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sounds more like a air leak in your tank to me...never had any of my engine run lean at a 1/4 tank of fuel. also out of 4 of the "older" styles that I have I have never had a issue with the carb and heat soak. and have ran 45 min mains before and always pulled off the track around 220
the new motor is made by a 100% different factory, the new CRF uses a standard Picco carb which will act just like every other Picco carb, i have modified and tuned several dozen Picco's and I found most need to have the carb body sealed....the first sign of the leak is a tendancy for the motor to overun off the jumps and also the need to tune the bottom end excessively rich........

What brand of machine is the motor acting up in, there are several manufacturers who have terrible fuel tanks which are prone to these symtoms
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Old 06-28-2008, 08:27 AM   #20
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the new motor is made by a 100% different factory, the new CRF uses a standard Picco carb which will act just like every other Picco carb, i have modified and tuned several dozen Picco's and I found most need to have the carb body sealed....the first sign of the leak is a tendancy for the motor to overun off the jumps and also the need to tune the bottom end excessively rich........

What brand of machine is the motor acting up in, there are several manufacturers who have terrible fuel tanks which are prone to these symtoms
The car is a brand new Xray 808, it's my first xray, but I've heard nothing but good things about the quality

I'm having the opposite "problem" on the picco carb - it doesn't like to run rich at all on the bottom end, I think I found the sweet spot, if I richen it up just one hour it will stall. Also, I've had to raise the idle more than other engines.

To put this all in perspective though, these are all very small problems, If the engine likes to run lean it likes to run lean, it's temping good between 220 and 250, if the idle needs to be high it needs to be high, no big deal, my only concern is a minor lean bog towards the end of the run. Maybe a colder plug to retard the timing will help? Right now I'm using a GRP #6 plug, it's in 90F where I am with a little humidity. Right now I have to give this engine an 8 out of 10

Question - I can probably take the carb apart and answer this myself, but I don't want to mess with it right now. I remember an article about two years ago in RC Car Action about the new technology in this engine...one of the features it was suppose to have was a finer thread on the needles - making for a bigger sweet spot - does anybody know if this made it into the production engine? Or is it truely a standard Picco Carb?
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