Ok...many of you know about my 03 kx250 the had the erratic idle and smoked like a mosquito fogger, then I jetted ! One size down on the pilot and the main. The bike was STRONG !!!! It ran better than it ever had and I was thrilled. However, I noticed it occasionaly going a little flat somtimes a little after 1/4 throttle and I had the needle all the way in the top position so I decided to pull the carb and put the clip in the middle position. Well I did and it went right back to sqare one...erratic idle and smokin' like crazy. So I put the clip back how it was, but it didn't get any better. I pulled the carb and went through it completely cleaning as I went....still running like crap, smoking, ect... Would an exhaust leak cause this ? I have a PC Works pipe w/ fmf shorty silencer. The pipe doesn't fit exact and it's a little off at the at the silencer coupling as well. Could it have maybe went togethr just right after I jetted giving the illusiom that it was the jetting ????
Here we go again....
- Thread starter cowasucky
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- #3
Yeh, brand new Boyseen pro series. What's crazy is It was running almost perfect....good enough I wish I would've left it alone ! I jetted....it was great. Dropped clip 2 spaces.....went back to how it was before I jetted. Put clip back bringing it all back to exactly how it was when it was running perfect.....still like it was before I jetted.
****everything is exactly how it was when it ran perfect!!! How could this jetting combination be perfect for Monday, but on Wednsday the same jetting combination is waaaaaaaay off. Same exact weather ??? It can't ! What could cause this ??? Float ? Needle valve ???
****everything is exactly how it was when it ran perfect!!! How could this jetting combination be perfect for Monday, but on Wednsday the same jetting combination is waaaaaaaay off. Same exact weather ??? It can't ! What could cause this ??? Float ? Needle valve ???
Definately NOT the jetting causing the problem. High float height is possible, bad float valve usually show as fuel coming from the overflow but should be closely inspected/replaced every so often. Also check the small air passages in the carb for obstructions, not just the fuel jets. A clogged air passage will cause it to go rich. You haven't recently cleaned air filter have you? Too much filter oil? If not, I would check the carb out first. If that was good, do a leak down test on the bottom end.
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What doesn't make sense is this..... what it is doing now is what the origional problem was. I pulled the carb to change the jets and it was 99 times better ! No smoke. Smooth Idle. Power out the wazoo ! Then at my quest for perfection, I decided to drop the clip, but that's all I did. When I put it back on, it went immediately back to square 1...smoking, erratic idle and power loss. So I put the clip back and it changed nothing. Everything is exactly where it was 3 days ago when it was "fixed". So obviously it wasn't the new jets that fixed it, but somthing happened when I changed the jets to 'fix it" and when I went back in fooling with it I undid whatever I did and now I can't figure out what the hell fixed it !!! The last time (yesterday) I pulled the carb, I took it completely apart, soaked all metal parts and blew everything out with compressed air. The carb is super clean....spotless!!! I'm litterally about to pull my damn hair out.... I had it runnin' great and I screwed with it and now I'm screwed !!!!! HELP !!!!!!!!!!
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But why did it run great till I pulled the carb ??? Don't get me wrong, I've received so much help and gained so much knowledge from each of you before. Matt, Joe and Jullien...you guys have gotten me through some tuff repairs before, but with all due respect I think you may be over thinking this one. The bike was running perfect other than an occasional, slight flattening out about 3/8 throttle. I have absolutely no doubt that I'd be ridding a fast, powerful, smooth running bike this weekend if I would have just left it alone. What I'm wondering is...suppose the crank seals are fine, the carb is fine....what could be done when putting the carb back on that could result in a super rich condition ??? Maybe a leak in carb boot ??? Float valve hanging up ? Those are just my thoughts, but if I were the smart one I wouldn't be asking you guys. Is there a right or wrong way to put the needle valve on the float tang ??? Backwards maybe ??? Also, my float can't go any lower....it rests on the bottom of the bowl. I just don't understand how the float should work..... I understand it floats up releasing the needle in the valve, but I don't see how it would close it since it can't go any lower than it is resting on the bottom of the bowl. I know I'm being repetitive and I apologize.... I'm just flabberghasted !!!
float level is set by turning carb upside down if you dont have the exact specs, just make tab level with carb body should be general ball park figure. the floats go up to close off needle to stop fuel flow into carb bowl. if floats are sitting on botton of bowl sounds like they are not adjusted correctly and fuel is continuing to flow and never shuts off, which should be where your smoking trouble is coming from. if you change the plug to a new one it will run good till it fouls again then you get hard starting and lots of smoke. just my opinion
if manual says air screw should be 1 1/2 to 2 1/2 turns out. i'd start in the middle and set it at 2 turns out. the idle screw is just to get the bike to idle. i normally set it to idle as low as possible where bike still has a 2 stroke sound(if you understand what i'm talking about no 4 stroke sound) it's just something you have to practice at to get good at it. let bike idle and hit throttle to clean out and bike should settle back down to same 2 stroke idle. if it hangs a revs hi the idle could be too high or too lean depending on sound bike makes. if it drops low into 4 stroke idle bike is too rich and you need to back out idle screw to lean bike out. this is about the easiest way i can think to explain it. hope this helps
Idle should be set to just pick the slide up off the bottom. It actually wedges the slide up, so if you back it out until the slide bottoms and then turn it in until it lifts up a bit you should be at a decent starting point.
It does sound like something that happened as a result of the carb removal, but all I can think of is high float height if all the passages are clean. That's my guess......
It does sound like something that happened as a result of the carb removal, but all I can think of is high float height if all the passages are clean. That's my guess......
sounds to me like its time for a bottom end if it hasnt never been done thats a long time on crank seals trans fluid making it smoke the very top of the needle is usally really lean so it cuts your mixed oil coming in so its burning trans fluid in its place so the smoke isnt as bad and eractic idle is from the left crank seal sucking air do a leak down test to find out
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- #16
_JOE_ said:
The gas is a couple weeks old. I had mixed up a gallon or so just to jet.....it's probably down to the bottom. Also, I had jacked with the throttle screw too....I noticed the slide didn't set all the way down in the groove. So here's where I am now.... I bought a new plug, went through the carb again (please just believe me that all passages are clear and the carb is immaculate), all jets are brand new. The only x factor is the float and needle valve. I bent the tang slightly and put it all back together. Set the air screw to 2 1/2 turns out and the throttle screw to 2 turns out. Cranked it up and it is much better, but not as good as it was. I'll play with the throttle screw tommorow. Also....the plug I took out was super oily and so much oil had blown out the gap I had where the pipe and silencer meet that it pooled on the swing arm. BTW I took care of that gap :cool:
Your float needle was working, then it quit, again. Screwy jetting? Change the float needle. Before it went again, it sounded like the needle is worn or get a leaner needle. Vintage Bob
