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Drew22

2009 YZ450F help

21 posts in this topic

Hello I just got a new 2009 yz450f and i just started to break it in. My issue is when I am riding at a steady speed, lets say half throttle the engine is kinda jumpy while just cruising. Is this normal during break in or is it supposed to do that since i am not used to mx bikes. Also the engine gets very hot compared to my trail bike did, is this normal too. Thanks

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I just got a new '09 a couple of months ago. Yes, was very jumpy during teh first hour or so but settled down after that. Still really jumpy with just a little throttle "idleing" through the pits. Hoping the offorad flywheel I bought will solve that.

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To me all YZ450f are jumpy as you call it. They are built to be turned all the way on or off.

Double check jetting......They are all a little jump at a cruise speed but just a little...if it is bad, double check jetting especially if it is getting hot

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Ok thanks for all the replies it looks like its normal. I just wanted to make sure it wasnt a jetting problem.

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Sounds like what my 09 did. From what ive heard, its your TPS sensor. Its recommended to unplug that sensor. I did, and all is good. No more jumpiness or hesitation at speed. Hope that helps.

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Sounds like what my 09 did. From what ive heard, its your TPS sensor. Its recommended to unplug that sensor. I did, and all is good. No more jumpiness or hesitation at speed. Hope that helps.

ok i am going to try that. Also is 93 octane ok to use?

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Why wouldn't it be?

Because in the owners manuel it says to use premium unleaded with an octane rating of 95 but where I live premium has an octane rating of 93 which I am sure that is ok to use. Also would shell v-power work well in this bike or should i just stick with premium.

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Because in the owners manuel it says to use premium unleaded with an octane rating of 95 but where I live premium has an octane rating of 93 which I am sure that is ok to use. Also would shell v-power work well in this bike or should i just stick with premium.

The fuel specified in the manual is 95 Research Octane Number (RON). The research method is not used in the US because it is not particularly applicable to the needs of modern engines. The more realistic Motor Octane Number (MON) produces much lower numbers but is a much more reliable approach. The US mandates the Anti-Knock Index (AKI) be posted on all gas pumps in this country, and that number is an average of the other two methods. You can see that on the pump as "(R+M)/2".

A US AKI number of 90 is approximately equal to a Research number of 95, so virtually any US pump premium meets the requirement.

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dont unplug the tps that ludacris! try a needle from a 06 or 07 yz450, half a clip richer and will smooth out the cruise at partial to mid throttle. also the best needle if u plan on installing a pipe in the future.

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dont unplug the tps that ludacris! try a needle from a 06 or 07 yz450, half a clip richer and will smooth out the cruise at partial to mid throttle. also the best needle if u plan on installing a pipe in the future.

"Ludicrous" is not a rap star.

Which needle do you prefer of the two you recommended? They are two different needles.

The '07 and '08 uses the NFLR, pn 5TA-14916-LR.

The '06 uses the NFPR, pn 5TA-14916-PR

Position for position, the NFPR is one half step leaner than the NFLR. What is interesting is that the NFLR is recommended by many people to make the '06 run better.

The '08 runs the NFLR needle in position 3 stock, one step leaner than the '07 runs the same needle. IMO, switching to the NFPR is splitting hairs at best.

To the OP, you might try raising the needle to clip position 4. If that makes it better, good, if it's worse, you are too rich instead.

To begin with, be certain your pilot circuit is trimmed out right. Then, see how much throttle you are using while experiencing this problem. If you are at less than 1/4 throttle, it may be more a matter of the diameter of the needle. If tweaking the pilot too rich makes it better, but raising the needle doesn't seem to help as much, try an NFLQ or NFLP needle (5TA-14916-L1 and 5TA-14916-LP), which are each a half step richer at the upper diameter.

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Sounds like what my 09 did. From what ive heard, its your TPS sensor. Its recommended to unplug that sensor. I did, and all is good. No more jumpiness or hesitation at speed. Hope that helps.

Would the bike even run without the TPS sensor plugged in? Is that for real? Sounds hokey :busted:

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Would the bike even run without the TPS sensor plugged in? Is that for real? Sounds hokey :busted:
Yes, it will, but the CDI looses its ability to map ignition timing based on both throttle load and engine speed. It sees the disconnected TPS as a full throttle signal (since this is the safer alternative) and controls timing by engine speed only on that basis.

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