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RPMs don't drop after warmup

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I just bought an 04 ttr125l. Bike appears to be completely stock. The motor idles fine when i first start it up, but once I ride for a bit, the idle never drops back down. It's like the bike is stuck on cruise control. I have checked to make sure the choke isn't stuck open, but after that really don't know what to do. Other than the extremely high idle issue, the bike runs, shifts, and accelerates fine. Any ideas?

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the choke piece inside the carb is siezed. it happened to me. i just rebuit the carb and lube the piece a little and the cable also.

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It's not the choke...

You're too lean on the pilot circuit. This is what's called a "hanging idle" (hint: search term) and usually can be cleared out by backing the fuel screw out a little.

If you're really lean you may have to go to the next larger size pilot. Rule of thumb is if you have to go out to more than 3-3.5 turns on the pilot fuel screw you need to bump the pilot up.

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And by the way, yamaha 125l brings up a very valid note for new ttr125 owners. You need to clean and lube the choke plunger every few months or it will seize in the bore and become inoperable. You can do a search on "stuck choke" and learn all about that too. :applause:

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I did do a search for the hanging idle issue, but it didnt' seem to match what was happening. I guess i'll do some work on the choke just to make sure that isn't it. (never hurts i guess) and see if that fixes it. Why would i be too lean if the bike is stock?

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is it idleing high when cold and just not idleing down when warm, there is an idle adjustment screw on the on the side of the carb under the seat, a phillips head screw.

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SOUNDS FAMILIAR, THE CHOKE PLUNGER IS SEIZED, AS FAR AS BEING LEAN FROM THE FACTORY, THEY ALL ARE, I HAVE A #20 PILOT & A 115 MAIN IN MY DAUGHTERS BIKE IT STARTS & RUNS FINE:thumbsup:

Sorry for shouting, I didn't realize the caps lock was on

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nope.. idles perfect when first started up... then after i ride a bit and the bike warms up, the rpms never drop back down... idles ridiculously high. for all you carb nuts, the bike's located in florida, in pretty much perfect weather.. if that helps.

took the choke plunger out. the whole carb is in perfect shape. no dirt, rust, anything. caught me by surprise actually. it's like the bike just sat in a garage for 3 years and got detailed every weekend.. :applause:

so as for that pilot screw. do I start with 3 turns? or do like 1 turn, see if that helps and just test and tune it? i'm really not very good with carbs...

thanks for the help guys

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The manual calls it a pilot air screw, but in real life we all know it is a fuel screw.

It's the screw on the bottom of the carb.

As I said before, it isn't the choke. :applause:

Just lightly seat it and count the turns as you go in for reference. It should be at about 1.5 out from seated if it is completely factory. This time of year down here I'd go straight to 3 full turns out and see how it does.

Chances are good it won't run right until you get to around 3.5, so you might as well go ahead and drop in a 17.5 pilot jet and reset it to around 2-2.5 turns out on the fuel screw.

This stuff comes up like once a month around here... I'm not just making this up.

Do yourself a favor and do the rejet/airbox/exhaust mods in the TTR125 jetting visual guide thread and the bike will run great. As for the fuel screw, you'll always have to adjust it as the seasons change. It's just something we have to deal with.

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if the bike sat for 3 years, you can bet that the jets are gunked up, maybe not clogged, but not clear. pilot jet clogged will lean her out. Tell me, when you start the bike cold, and take it off choke right away, is there a change in idle? Will it start without the choke when its stone cold? If you answerd :yes :no, you dont have a choke problem. take off the bowl and clean out the jets, get rid of the 3 year old gas, all of it, and then adjust the AIR SCREW out until it runs the highest rpm. then adjust the idle down.

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That is a good point about the jets being dirty with the old gas in their Gary, and the only reason I didn't suggest that as well is that he said it starts fine and runs great until it is warmed up and then it gets a hanging idle.

If it was a clogged pilot jet it wouldn't idle without the choke being on, at least usually. In order to start fine and warm up smoothly, and then have a hanging idle when its warm he either needs to adjust the FUEL SCREW or go to a bigger pilot jet. I would adjust the screw first because its easier than changing the pilot jet out, but if that doesn't get it by about 3.5 turns out it will be time for a bigger pilot jet.

Most of these bikes really seem to benefit from a 17.5 pilot even if they don't have intake or exhaust mods, especially here in Florida which is so near to sea level (read: more dense air). If you do any mods to it at all then the 17.5 is borderline not big enough.

And for the record, the manual saying that this bike has an air screw is widely regarded as a misprint. An air screw meters air so going out on it increases the air in the mixture and leans it out. A fuel screw lets more fuel in the mix when you go out on it which makes the mixture rich. This bike definitely has a fuel screw in it.

Still, your advice to clean out the jets after sitting for 3 years is spot on, but won't fix the hanging idle problem most likely unless it is done in conjunction with a fuel screw adjustment.

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well i didnt say it *actually* sat for 3 years, it just noticed the carb was like brand spankin new...

Gary: when i first start the bike i have to wait until its pretty warm before i take the choke off otherwise it will just die on me. i really cant start it without the choke.

but, i already took it apart and the choke cable, spring, etc etc are all spotless, so unless i'm missing something that's not the problem.

I guess i'll try it out tomarrow and see if the fuel screw thing helped. Then maybe this weekend look into the modding/rejetting situation

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well here's an update:

adjusted the screw out to 3. started first kick with teh choke on. idled perfectly when i put the choke back in. seems to be more responsive as well. so this did help a bit. it still idles way high though after i rode it around the block once. maybe not quite as high... but still too much.

edit: tried 3.5 turns... bike runs pretty good. started first kick with no choke! so i'm pleased... BUT it still idles way high... again, this is only after it warms up and idles fine before i ride it so i dont think its an idle adjustment thing or whatever. does anyone have any other things i could check to make sure its just the jetting and not a spun bearing/squirrel in the intake/etc?

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I would look into the next size pilot jet. Almost all bikes are lean from the factory. A bigger pilot jet almost always helps. Give it a try. Its cheep.

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well problem is solved! Thanks for all your help guys! :applause:

Started the bike up and instead of idling low like it had been doing, it just started up idling really high. So I turned the idle adjustment screw out about 2.5 turns to lower the idle down. seems to be working perfectly. Started first kick without the choke and runs pretty darn good!

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Why can't all of life's problems be so easy? :applause:

It does sound like you still need the 17.5 pilot jet though. If you have to be out 3.5 turns at this time of year, when it cools off in the fall you won't have any more screw to give it and if you go out past 3.5 there is a good chance it will vibrate out and you'll lose it.

On the TTR125 you really only need to adjust it several times a year, but my YZ450f needs a tweak almost every ride. The bigger bikes are a lot more tempermental than these are.

Glad you got it whooped. :eek:

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yah i'll probbaly end up with an exhaust soon and work on the airbox etc... so, it will be rejetted before too long... :applause:

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You know, it doesn't cost anything at all to read threads around here.

People like you better when you read all of the posts in a thread before you add your 2 cents...

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