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Old 10-31-2008, 11:22 AM   #1
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Default ninja jx21 problems

got my engine tuned by a local hobby shop ran great for a while. Ever since the weather got colder it started running crappy and started turning off. now its running great to me but having lots of trouble starting it after running it notice it starts easier with the air filter off and also notice lots of fuel spitting out the carb i guessing its rich but like i said it runs great while running please help.
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Old 10-31-2008, 11:32 AM   #2
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Im not sure if this will help, but does the slide open and close easily? Mine was very tight and would stick....causing all types of problems. I had to take the slide out and use a scotch bright bad then a buddy filed it down in one of the grooves. There must have been a little burr in there cuz its very smooth know and runs great! I was a little bumbed about the motor at first, although Im very impressed now.
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Old 10-31-2008, 12:04 PM   #3
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First of all! don't ever start your engine without an air filter.
the reason it's hard to start when it's warm is the piston expands as soon as you hear that very first pop. when the engine is fully broken in it will start much easier.

You should read this entire thread. http://www.rctech.net/forum/nitro-of...ugen-jx21.html
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Old 10-31-2008, 01:45 PM   #4
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Quote:
Originally Posted by jpalessi View Post
First of all! don't ever start your engine without an air filter.
the reason it's hard to start when it's warm is the piston expands as soon as you hear that very first pop. when the engine is fully broken in it will start much easier.

You should read this entire thread. http://www.rctech.net/forum/nitro-of...ugen-jx21.html
and also, heat it up before evry start with it being new, and the tune or air fuel ratio will change from afternoon to evening, during the evening the air is so clean it will cause the motor to lean VS afternood running when the air may have more humidity=dirty air, also what plug are you running, if you run in low himidity try using the OS P6 or cooler, clean air running doesn't require ultra hot plugs.
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Old 10-31-2008, 02:10 PM   #5
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Even stock cars that run on alcohol have trouble staring in cold weather. Heat up the motor with a heat gun and it will fire right up.

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Old 10-31-2008, 03:43 PM   #6
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engine has been fully broken in with 8 full tanks of gas...my seems to be opening and closing perfectly fine, plus im using a p3 os ultra hot plug...the main problem I'm having is the car won't start after I turn it off and it's off for no more than a min with engine already warm...I notice that gas spits out of the carb during cranks and the reason why I take out the filter is because it seems that the gas spits out in the filter and then drips back down in the carb causing it to flood
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Old 10-31-2008, 05:24 PM   #7
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when you stop it and its a little warm, the fuel inside the engine will boil out. thus acting out of fuel when trying to start. try unhooking the pressure line from the pipe and blow through it and watch the fuel go to the engine. then start it. should help.
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Old 10-31-2008, 05:37 PM   #8
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Quote:
Originally Posted by ccordero85 View Post
engine has been fully broken in with 8 full tanks of gas...my seems to be opening and closing perfectly fine, plus im using a p3 os ultra hot plug...the main problem I'm having is the car won't start after I turn it off and it's off for no more than a min with engine already warm...I notice that gas spits out of the carb during cranks and the reason why I take out the filter is because it seems that the gas spits out in the filter and then drips back down in the carb causing it to flood
8 tanks of gas do not = fully broken in. When you have ran a 1/2 to gallon of fuel through your engine it's fully broken in.
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Old 10-31-2008, 06:16 PM   #9
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Old 11-01-2008, 06:01 PM   #10
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the engine has about 1 1/2 gallons of fuel through it. well today i took it to my fav hobby shop and to them it seems to be the con rod. it runs fine when on just takes foe ever to start after its been on they said it has play and thr kid who told me that is the engine builder kid at the shop and hes also a nat racer so im guessing he knows what hes talkin about but we'll see.
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