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Jetting 05 YZ450 with Carbon Pro?

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I just put a White Brothers Carbon Pro Pipe on my new YZ450 and I'm having a heck of a time getting it jetted correctly. The local dealer told me to put in a 48 slow and 170 main for the new pipe. I went out and rode it pretty hard at the local track in about 90 degree weather and it ran pretty good. I thought it could have ran better, but it was ok. I pulled the plug to see what it looked like and it was white indicating that it was running lean. I also noticed that hte bike seemed to be running a little on the hot side also indicating that it was lean.

One other problem I have with the bike now is that when it's on the stand and the throttle is cracked quickly bogs or pops and dies.

Any ideas?

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What type of fuel are you running?

The pilot jet seems too rich for most YZ450F's, including the one I just tested with the same exhaust.

What needle clip position?

James

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I was running pump gas, with the clip at #4 stock setting. All other carb settings are stock. The only other modification on the bike is a Twin Air Filter kit that removes the plastic backfire screen.

Thanks!

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The '05 YZ450F is going to be leaner than previous years, mainly due to jetting revisions. I would try a richer clip position as a first step.

The jetting kit will run cooler with a more balanced jetting (not so lean) across the throttle range. It adds more torque over standard factory jetting and will keep or improve on the top-end power.

James

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I will try the richer clip position this weekend and see how that works.

I'm new to this forum, but your jet kits seem to be the ticket. As soon as my wife gets over the cost of the new bike plus White Brothers Carbon Pro I will have to pick one up and give it a try.

Thanks,

Joe

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I tried the needle one clip richer along with the 48 slow and 170 main and even came out another half turn on the fuel screw and the bike was still lean. I suspect that something else is going on with the new 05 YZ 450's causing them to run lean. I can't imagine that mine is still lean after going fatter throughout the entire circuit.

It ran ok with this configuration, but a few times when I first entered the track it seemed to be a little rich until I got on it and started hammering out some laps. Once on the pipe it seemed to run strong. I pulled the plug and it was still white as it was before?

I talked to White Brothers and they said to go back to stock on the needle and turn the fuel screw out 1 full turn from stock with the 48 slow and 170 main. So, I'm going to try that this weekend and see how it runs.

If anyone has had success jetting the 05 YZ450 please let me know. I would like to spend more time ridding and less time jetting in the future.

I really don't care if it's lean as long as it runs strong. I purchased the engine insurance so if it blows I will ride my 03 until it's fixed.

Joe

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one clip richer along with the 48 slow and 170 main and even came out another half turn on the fuel screw and the bike was still lean. I suspect that something else is going on with the new 05 YZ 450's causing them to run lean. I can't imagine that mine is still lean after going fatter throughout the entire circuit.

It ran ok with this configuration, but a few times when I first entered the track it seemed to be a little rich until I got on it and started hammering out some laps. Once on the pipe it seemed to run strong. I pulled the plug and it was still white as it was before?

Regardless of what the plug looked like the jetting you used appears to be rich and so are the symptoms. The recommended jetting should be to use the stock pilot jet and 1 step richer clip position.

James

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I ran it this weekend with the jetting recomended by White Brothers and it seemed to run better. Still thought it was a little rich possibly off the bottom.

I can try one richer on the clip with stock jetting and see how that works. However, the 05 YZ 450 comes stock with a #45 pilot Jet?

Thanks,

Joe

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The '05 is using a #45, while the '03/'04 ran a #42 pilot jet. If it feels rich at low speeds with the #45, turn the fuel screw inwards.

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I feel that it is lean with the 45 so I went to a 48 piolet and a 168 main, but I have not had the chance to run her yet! :cry:

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JD

You mentioned that regardless of what the plug looks like the symptons sound rich. I am having the same issues with a bone stock 05 YZ450. I am starting to think that there is a bigger issue and am waiting to hear from Yamaha. From day 1 this bike has run extremely hot compared to the 04. Also the plug was totally white on one side and a bit black on the other.

I went up to the 170 main and also lower the clip and turned the pilot screw out another half turn. Definitley seemed to help but plug still looks very lean.

I am at 900 feet, air temps in the 50's

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I'm still having problems with mine. The local shop says that even stock the bike needs a 48 pilot and 170 main. Mine still doesn't run that good and I was thinking of going up to a bigger main to get a better plug reading and see if that helps. The best results I have had so far are with the fuel screw at stock 1 3/4 turns out and the 48 pilot and 170 main. The problem with jetting this bike is that you can't get to the carb to change jets at the track. I still need to try all stock with the clip lowered on notch (richer) and see how that works. This was recomended by JD in an earlier reply to this thread.

Joe

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I'm still having problems with mine. The local shop says that even stock the bike needs a 48 pilot and 170 main. Mine still doesn't run that good and I was thinking of going up to a bigger main to get a better plug reading and see if that helps. The best results I have had so far are with the fuel screw at stock 1 3/4 turns out and the 48 pilot and 170 main. The problem with jetting this bike is that you can't get to the carb to change jets at the track. I still need to try all stock with the clip lowered on notch (richer) and see how that works. This was recomended by JD in an earlier reply to this thread.

Joe

So how did stock work with the clip lowered one notch?

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Try a richer clip position rather than richening the pilot or main jet. The excessively rich pilot jet will usually cause the idle to be too rich, despite the lean mid-throttle.

The jetting kit should solve these issues with a more balanced jetting from the needle design. None of the other brands of bikes use pilot jets above a #45, even with lean needle designs.

James

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I will give it a try soon and drop the needle one notch(richer) and see what happens. My bike runs good, but just pops on decel. I tried backing out the fuel screw a bit without much of a change.

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