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post #1 of (permalink) Old 01-10-2004, 08:05 PM
countrymike
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300ex jetting help

i have a 2003 honda trx300ex. i just installed a supertrapp IDS2 full exhaust, headpipe and all, a k&n airfilter, and a dynojet jet kit. my problem is if i go to rev the motor right off of an idle it just falls on its face, it won't rev up. now if i increase the throttle really slowly the engine speed will increase, and once the motor is wound up i can freely rev it as i please. i first thought it was lean so i changed the main jet from a 118 to a 120 and then later to a 124, and it just got worse. so then i leaned it out all the way down to a 110 in increments, and still it did the same thing. so i put the 118 back in and started adjusting the fuel mixture screw, and it still does the same. i'm out of ideas and ready to flip out, does anybody have any suggestions on what i should try next. i would really appreciate any help i can get.

Thanks
Mike [img]images/graemlins/AR15firing.gif[/img]
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post #2 of (permalink) Old 01-28-2004, 10:10 AM
 
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Re: 300ex jetting help

it may be that your pipe is not connect right, or your filter not installed properly, a possible leak in your air boots, but I really have never heard something like that coming from jetting....good luck
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post #3 of (permalink) Old 01-28-2004, 12:41 PM
 
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Re: 300ex jetting help

It sounds to me like the pilot jet is too small, I would leave the main set where you had it running good up top, and start going bigger on the pilot jet and see if the stumble goes away. The main doesn't do much right off idle, that's where the pilot jet comes into play. With all the extra air you're flowing now, it probably needs to be at least a few sizes larger to even out the mixture once you crack the throttle. Once the engine picks up rpm's, the air flowing thru the carb finally makes enough vacuum to draw the fuel from the main jet, until you have that vacuum built up, the pilot jet does almost all the work. Once you get the pilot jet figured out and it stops stumbling off idle, make a few wide open passes then pull the clutch in and hit the kill switch. Pull the plug and check the color inside on the insulator and see what color it is, white is too lean and will kill the engine, black is too rich, light tan to brown is just right, adjust the color with your main jets. Hope this helps, let us know if it does, if not we'll have to do some more thinking until we get you running right. [img]images/graemlins/40BEER.gif[/img]
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post #4 of (permalink) Old 01-28-2004, 01:53 PM
 
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Re: 300ex jetting help

I am sorry,
I read your post wrong [img]images/graemlins/grin.gif[/img]....yes, either your pilot is to large or small...but I had this very same problem...it would die out and bog and sputter on low rpms...

the problem when I had it, is I did not set-up the needle correctly, so it ws just bouncing around in the slide, mine was able to idle, but anywhere from 1/8 throttle to 3/4 throttle it would bog out, this may be your case, or may not, when you were jetting your machine you could have replaced or touched something that wasnt supposed to be touched or changed, or maybe something is plogged?

will the machine idle? if it does your pilot is good, if it is only the time when letting out the clutch to 3/4 rpms its your needle...if this problem only occurs at high rpms, most likely your main jet....my guess is check your needle, good luck
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post #5 of (permalink) Old 01-28-2004, 07:35 PM
 
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Re: 300ex jetting help

Ian , it could still idle if it is not too terribly small on the pilot jet, yet still stumble from being too lean with a quick twist of the throttle.
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post #6 of (permalink) Old 02-12-2004, 04:09 PM
countrymike
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Re: 300ex jetting help

Thanks, for the responses. i had a bit of a brain fart while doing this and i raised the needle one notch and i solved the off idle problem but now the quads running a little rich throughout the whole rpm range. i haven't done anything to it in a while, working too much and no time to ride. but i'll lean it out a bit and let you know how i'm doing.

Thanks,
Mike
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