tried to tune carb...lol

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valleyguy
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tried to tune carb...lol

Post by valleyguy »

Okay, I spent some time trying to fix my carb issues, even printed off the sticky and had it beside me during. So turning the idle screw changed nothing for the idle so I manually cracked the throttle a tiny bit then moved on to the air screw (which was turned out almost as far as it would go) started at 1.5 turns and screwed it and out, also no change in idle so as I'm staring at it in confusion it bogs down and quits and will not fire up without the choke but then dies again pulled the plug and its wet and black and i noticed the bike was smoking quit a bit. Any ideas? A local guy said he could tune it for 100 bucks but he wouldn't get to it for 2 weeks but I'd rather do it my self. I had.no problems tunning the holly on my trans am but this thing baffles me. 90 kdx 200 all stock except a rebuild and fmf gold series pipe and fmf power core muffler 92ft above sea level. Thanks in advance.
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scheckaet
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tried to tune carb...lol

Post by scheckaet »

100 bux??? :shock:
save your money and do it yourself, the only thing you need is some jets and some patience.
1st you're headin in the right direction by using the tutorial :supz:
2 what jets do you have in the carb right now?
3 have you cleaned and inspected the carb recently?
4 air filter clean?
5 fuel line not plugged up?
6 any air leak around gasket?
valleyguy
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Re: tried to tune carb...lol

Post by valleyguy »

Not sure what jets are in it, he said he opened them up with a drill bit. I'm gonna order a few different jets around 155/48 and start again. Carb is fresh fuel lines are all new and I just did the filter as well as a plug (dr9es) thats what was in it when I got it. I'm gonna have to grab a few plugs i guess. It ran alright below half throttle except for being sluvish if you cracked it open quickly. What would make both screws have nothing to do with the idle at all? I can't get it to idle at all once it warms up it just bogs out and quits and is a pain to start again.
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Julien D
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tried to tune carb...lol

Post by Julien D »

Guessing you meant BR9ES, which is fine. DR9ES would be a 12mm plug, won't fit.

First thing I would do is get rid of those drilled out jets.
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valleyguy
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Re: tried to tune carb...lol

Post by valleyguy »

Just took the carb off the bike and tore it completely down. Not one spec of dirt or crud in it. Jets are not drilled don't know what previous owner was talking about and they are 48/152 they are clean and in great shape, needle has no marks on it but I didn't take a look at where the clip was for some dumb reason. So tonight I'm gonna take it for a ride to warm it up and throw in a new plug and try again and see what happens. Sorry for all the post about this but this thing is driving me crazy I just wanna go ride lol
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Julien D
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Re: tried to tune carb...lol

Post by Julien D »

I'm not sure how you think you'd be able to tell if he drilled the jets out to a larger size. It would really not be visible by eye, unless you had an unmolested jet of the same size to compare it with.
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tried to tune carb...lol

Post by KDXGarage »

Hi. Since you are down on the coast and have high temperature right now, give these a try, based on my own experiences with jetting my 1994 KDX200 (which is the same engine, carb and such as yours).

For me, at 1000 ft elevation, 73 degrees, I was at:

45 pilot
2nd clip on an R1173N needle (one thicker than stock based on FRP Offroad recommendation for the aftermarket pipe, cleared up richness at 1/8 throttle)
stock slide
1.5 turns out on air screw (for starters)
150 main

48 pilot jet is going to be too rich for you.

If you are under high load in the sand dunes, a 9 heat range is OK. If you are on trails on a 1989 - 1994 KDX200, switch to an 8 heat range plug. (B8ES or BR8ES)
Thank you for participating on kdxrider.net. :bravo:
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valleyguy
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Re: tried to tune carb...lol

Post by valleyguy »

Julien D wrote:I'm not sure how you think you'd be able to tell if he drilled the jets out to a larger size. It would really not be visible by eye, unless you had an unmolested jet of the same size to compare it with.
First off thank you very much for all your input you have been very helpful Julien D as well as others. I do have a set of stock jets here that I compared them to, I picked up a few jets to try because you had stated to try a 48 and a 155 but all they had in stock was a 48 and a 152 as well as some lower ones so I took the 48 and 152 and thought I would start from there but that was what is already in the bike, everything seemed fine with the old ones but I threw the new ones in just to be safe.

As for the other post, thank you I'll look into it like I said for some dumb reason I didn't even check out the needle size I just checked it for scratches and left it all assembled thinking I would find a problem in the carb and then just put it all together again. :roll: as for high loads it's just gonna be a trail bike with some long wide open sections.
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Julien D
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Re: tried to tune carb...lol

Post by Julien D »

Gotcha. The jets Jason recommended will probably be closer, I was just trying to get you to a starting point. So with your new jets it runs the same as it did with the "drilled out" jets?
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valleyguy
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Re: tried to tune carb...lol

Post by valleyguy »

yup, but i have to play around with it tonight when the wife gets home Im at home with the baby and Im sure he has better things to do then sit there and watch me swearing at my bike lol So really I didn't get to try it out yet but I'm 100% positive the new jets and old jets where the same because I used a tooth pick and marked where it stopped on the new ones and checked it against the old ones and was bang on. Don't ask me how I thought of a tooth pick but it was tappered and was small enough lol So I should switch to the 8 heat range ?
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Re: tried to tune carb...lol

Post by Julien D »

I run an 8 in my KDX, and that is what I would generally recommend.
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Re: tried to tune carb...lol

Post by valleyguy »

awsome, thanks
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tried to tune carb...lol

Post by fuzzy »

What would make both screws have nothing to do with the idle at all? I can't get it to idle at all once it warms up it just bogs out and quits and is a pain to start again.
Do a compression test.
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valleyguy
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Re: tried to tune carb...lol

Post by valleyguy »

ok update, I finally got things somewhat turned in the right direction. I redid the tunning sticky except for the plug chop because I only had two plugs and I put one in for the tunning so I'll wait till I get another one and try it later but I've got it perfect on the bottom 1/4 of the throttle it will now pull the front wheel up on comand just by goosing it, but after that 1/4 throttle its like the brake is dragging and it goes from pulling hard to pulling like a 50cc doesnt bog down or sputter just kinda flattens out and slowly gains rpm no matter if you crank it or slowly open the throttle. any ideas where to go next? specs are as follows: pilot jet 48, air screw 2 turns out main jet 152 and needle is NR1171 and the clip is third from the top.
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Julien D
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Re: tried to tune carb...lol

Post by Julien D »

Try lowering the clip on the needle. Sounds like you might be lean in the middle. If that makes it worse, go the other way.
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valleyguy
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Re: tried to tune carb...lol

Post by valleyguy »

I'll give that a try tonight, it seems like its close. although I'm still having a bit of a problem with the idle when it's warmed up as soon as I come to a stop it stalls unless I give it a bit of throttle then it it seems to smooth out after a sec.
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tried to tune carb...lol

Post by Julien D »

I would go ahead and set your idle after it's totally warmed up. If it idles a bit fast while it's cold, and then slows to normal once it warms up, that'd be about right.
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tried to tune carb...lol

Post by fuzzy »

Indeed.
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valleyguy
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Re: tried to tune carb...lol

Post by valleyguy »

Thank you everyone for the help it's almost there, changing the clip one down made a a big difference it now pulls pretty good throughout the rpm range, but it still seemed to be held back a bit. I'm going to repack the muffler cause I finally got it apart tonight and its pretty bad, hopefully it won't mess with me current setup to much. I think I'm gonna make a video of it tomorrow so you guys can have a listen and see what you think.
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Re: tried to tune carb...lol

Post by amstel78 »

Stupid question I know, but how do I disassemble the needle holder to change clip positions? Looking at the service manual, there's no real mention on how to change that.
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