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Powerband Hitting Too Early?

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I have a 2006 YZ125, and I was out riding today, and it is rather cold (46f). After about an hour of riding when I went about a quarter throttle it would go into the powerband. I am wondering if it was just too cold for the bike, or if there is a problem. The piston and rings were recently replaced. I also had just put in transmission fluid. Any help would be appreciated.

Mason Shear

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your bike sounds like its running really lean for some reason. my 2fiddy will do that if i forget to turn the gas on then it dies. check your carb to see if its dirty.

does the bike run fine when your WFO?

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Yeah, the bike runs fine WFO, I don't see how it could be the gas as it was doing fine until about an hour into riding. The carb is clean.

EDIT: come to think of it, it has a lot of oil in the gas. It was smoking pretty bad, maybe that is the problem.

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Like the bike hits full power on 1/4 throttle. Not really sure how to explain it.

Power valve stuck.

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From what you explained it just sounds like the power is hitting early..right?

Well you know that the colder it gets, the more power your 2 stroke will make. So if you rode in say 10f it would make a bunch more power than it does at 60f.

This is why snowmobiles make so much power.

Go into more detail and maybe we can help you better.

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Well when I give it a little gas it gets right on the power band, and if I switch gears it just stays on the power band. If you give it more throttle it doesn't improve the speed by much. It is almost like my bottom end isn't there. It feels like I should be switching gears as soon as I hit the gear. Not sure if I can explain it any better than that.

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Yeah, the bike runs fine WFO, I don't see how it could be the gas as it was doing fine until about an hour into riding. The carb is clean.

EDIT: come to think of it, it has a lot of oil in the gas. It was smoking pretty bad, maybe that is the problem.

Contradiction, sounds like it's running lean but its smoking.

Is it consuming rad fluid? Is the smoke blue or white?

Did you use a different (or new) gas mixture just before it started running different?

If it was running fine for an hr then started running lean, possibly, a spec of dirt that was in the gas tank might have made it to the carb & is clogging the main or power jet, reducing fluid flow through that circuit. By clean I think the others trying to help meant inside the carb.

Do you have the manual?

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Sounds to me like your clutch is slipping. No or little load on the engine it is easy for it to achieve max rpm's fast.

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Another thing that you might want to check is the spark plug to see what color it is. Most bikes are jetted for 70+ degrees. There is more oxygen in the air that creates a leaner condition that will make your bike run differently than usual. You might want to check the other things out as well that people have been commenting on. If you go to extreme temp. differences with your stock jetting (like running the bike around in 30 degree weather, you also have a bigger chance of smoking the top end due to more oxygen in the air = leaner running condition = bye bye top end). There are other things like mentioned before, but you might want to watch it.....Good luck!

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Like the bike hits full power on 1/4 throttle. Not really sure how to explain it.

are you sure your not riding a 4 stroke ?? :lol:

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How long has it been since the last time you freshened up topend? Maybe your bike had been running a little flat & you hadn't noticed how bad it was getting. More than likely this is the way your bike should have been running if jetted properly at warmer temps, meaning you are probably a little rich on the needle & main warmer temps. If you are concerned about WOT seize richen your main a little, the motor zinging to high rpm's at small increments of twist is more related to the needle adjustment & probably won't increase your chances of engine trouble.

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