KX Riders
Maintenance & Technical => KX250 / KX125 => Topic started by: onetwofiver on January 23, 2014, 11:35:52 AM
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My 02' kx125 has the TMX carb and has been running fine since August. Trail riding but plenty of wot also. Now it's fouling plugs all of sudden with 32:1. Today tried new plug and 40:1 and still the same thing. I'm planning on trying a smaller pilot jet. Pulled carb today and bowl is clean. Tomorrow will get into it more.
Another question: What are signs of worn reed valves?
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I wouldn't touch your jetting till you inspect your reeds.
Taking the reeds out and looking for gaps in the reed petals to the reed body is one easy way to see if they are worn.
Gaps are bad.
Still, you can have reeds that are worn out and they look ok.
A quick test is to remove your air filter and start your bike.
Put your hand at the intake opening of the air box and rev the motor.
If you can feel air blowing back out of the carb replace your reeds.
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Thanks.
Something else, it will start, run good then bog and die within about 20 seconds. Bowl had plenty of gas in it. I'm gonna check the pilot jet, maybe it's half clogged? Then the reeds. Then ......
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Float height.
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That is on my list too.
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these are the key words...
fouling plugs all of sudden
Like Sandblaster said...don't touch the jetting until you check the reeds. Jetting won't suddenly change unless...your needle broke...or your main or pilot jet backed out and fell out...your filter is disgusting... or you sucked dirt, but this usually won't cause plug fouling as it's restricting fuel flow.
Out of curiosity, what does the plug look like when it fouls out?
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Filter is clean/oiled. Jets are in tight, plug looks fouled/black and wet.
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worst case scenario...you could have an electrical problem, which could be as simple as a bad plug cap, to as bad as a junk stator....but that's the last thing you want to think about. :x
Is there a specific RPM range that it's fouling plugs?
Start with Sandblasters suggestions 1st though before getting into anything else.
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Plug cap was replaced a few months ago because the old one had a slight tear. It's fouling at about 1/2 throttle. I need to find the float height setting. Should it be the same as a stock carb?
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I need to find the float height setting. Should it be the same as a stock carb?
I'm not 100% sure on that...let Sandblaster chime back in, he should be able to answer that better than I can...since he eats, sleeps, and s**ts dirtbikes :-D
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Have you ever pooped out a dirt bike?
It's not pretty....
Here's a link on How to adjust your float bowl:
http://www.oem-cycle.com/forum/viewtopic.php?f=40&t=586 (http://www.oem-cycle.com/forum/viewtopic.php?f=40&t=586)
I don't have the height for your carb memorized but before you fiddle with that, check your reed first...
Just out of curiosity, did your bike start smoking after you cleaned or replaced your air filter?
If so there is a good chance that you used to much oil on the filter and your restricting the air flow....
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Have you ever pooped out a dirt bike?
I haven't...but I'd sure love to be able to poop out a new cylinder/top-end from time to time. :wink:
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Hows the trans oil level? I would check float height, reeds, needle, slide, and do a leak down test. If it just started acting up out of no where I would almost put money on clutch side crank seal sucking trans oil. Check the easy stuff first.
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OK, It's running again but not the way it should yet. I did change the trans oil just to look at it and smell it. It was still normal. Refilled with new 30w oil. It had 15/40 rotella .
Here's what we have.....
I cleaned the pilot jet, size 45. Maybe I need to go smaller? It was slightly clogged with dirt maybe.. So I guess the main jet was sucking too much gas to make up for it.
Now, it starts right up and runs good wot but will cut/bog then back to normal. Will check the plug tomorrow.
Now I'm thinking it needs reeds?
Goat:
Hope it's not a clutch side crank seal. Does that require a bottom end rebuild? Any other symptoms for that?
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Hey, maybe I need to repack the exhaust ?
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If it's the clutch side crank seal your oil level will slowly drop depending how long you ride it. It will always run rich if it's bad. Mag side will suck air and run lean and potentially seize the piston. Seals get pressed in from inside so the crank and bearings have to come out. If this is the issue I would replace the bearings as well since you have to remove them anyway.
I'm very picky when it comes to my engines. If it's needing a rebuild I generally pull the entire engine apart and inspect everything and replace crank bearings and seals at least once every other rebuild. Sometimes more. I don't like breaking down as most of my riding is 2+ hours from home and ya always break down far away from the truck. I take better care of my bikes than I do myself :P
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Thanks for the advice. The oil level has stayed the same so maybe it's not too bad. I agree if I need to get into the bottom end may as well replace what needs replacing while in there.
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Thanks for the advice. The oil level has stayed the same so maybe it's not too bad. I agree if I need to get into the bottom end may as well replace what needs replacing while in there.
It can be expensive...but like Goat said, if you need to open up the bottom, just replace everything whether it needs it or not....there's nothing worse than having a failure because you assumed a bearing was "ok", or that seal is "good enough" , or the snap rings seem "ok"....trust me, been there and it sucks. There's really no sense just replacing a couple bearings, because now you'll have old ones that will need replacing sooner than the new ones, which means splitting the cases AGAIN....it's better to keep everything uniformly new.
And it really gives you "peace of mind" knowing that your bottom end is new.