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Figure this out.. TTR 125 Idle Problem..

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My friend has 2004 TTR-125. Starts instantly, runs smooth,(stock jetting) valves checked/in spec. Carb has been checked/cleaned/ No air leaks.. Riding the bike around the yard, when you come to a stop it idles perfectly. while other times you come to a stop and it idles all the way down to nothing & dies... It does not have a hanging idle.. it's very random.. Basically about 50% of the time it idles perfectly, the half it simply dies, although it starts back 100% instantly and runs fine, no missing or hesitation. Could it be just bad gas or small debri in tank causing intermitten problem.. The bike does have a extra long air vent on gas tank..although I'm not sure this could make a difference.. Send me some opinions.. hold the ignorant comments. All help appreciated. Bike has fresh Premium Fuel. I realize the bikes are very lean on the pilot from the factory.. but it does idle perfectly 50% of the time.. unless the small pilot is starving the bike at idle speed and causing it to die every so often..

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It could very well be a vacuum in the tank causing this problem...

Try a new tank vent with the stock setup and see if the problem goes away. It may just be making a small vacuum, but not perfectly sealed. That way after it stalls it leaks air in and starts right back up.

That's about all I can think of...

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the tank vacuum is the likely culprit, but maybe try cleaning the carb also? debris in the tank is not an issue, because the petcock has a filter element built in. i would say some small pieces of dirt could be clogging your main

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I mentioned the Tank Vent hose just to be accurate on all the details.. Although it's exactly like the stock vent hose, I just can't believe pluggin in a different hose that's maybe 4" longer than the stock one could make a difference, the stock vent hose broke, so the owner simply purchased one at the local dealer. As for the carb cleaning, I've covered that. I got to ride the bike today for 30 minutes or so and it runs fine, it just idles down and dies occasionally. Other times it will sit and idle perfectly for as long as you let it, so the problem is very random, which makes it hard to diagnose in my opinion.

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I did see an article on some after market (Chinese) vent hose screwing something up, but I don't remember what it was. Check your fuel line, mine was kinked once. Check your check and make sure it's not on a bit. Get a new spark plug. Try someone elses carb.

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Check Throttle Cable and make sure the slide free and that it rest on the idle screw....sometimes a tight cable and keep the slide from hitting bottom.

Those pilot jets are tiny so double check it....mine gets clogged at least once a month.

Did you do the carb cleaner spray check for air leaks??

Double check for a clogged/kinked Vent hose coming off the carb....

These bikes are so dependable and simple it's gotta be somthing fairly obvious....good luck

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Make sure he didn't install the vent in the line backwards...

It really sounds like a vent problem to me still.

:thumbsup:

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Here's what I've read here several times. The carb is set extremely lean from the factory. Close the fuel screw, and open it back up 1 full turn more than it was.

Try that and report back....please. :thumbsup::ride:

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