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2007 YZ450f jetting for glamis


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Cool deal, thx. This carb is a p.i.t.a to get to anyway.

If you have stock main jet, you should probably go next size larger . . . you will be WFO/running it hard in the sand and big hills, right???

Changing MJ takes 5 minutes or less. no carb removal necessary.

Don't want to starve that big motor with a stock MJ in heavy throttle conditions. my '08 works good with a 165 in it, at ~450 ft alt and spring/summer temps. I believe stock is 160 or 162, not sure though.

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WOW! lol That was so unbelievably easy. It really seems to respond to the throttle wayyyy better now too. Not sure if I'm just paying more attention but the throttle really did seem nicer. If it didn't have a paddle on it I'd ride it around. It also started first kick after turning the fuel on. Last time I drained the bowl it took a few kicks to get started.

It idled fine like you said no change there. Did have a bit of a bog on quick throttle snaps like before but I'm considering that normal from what I've heard.

I hope I don't have to mess with the mixture screw as I don't have one of those cool twist adjusters installed yet.

thanks again

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FWIW, I just got back from Glamis after riding my new 09 YZ450F. It has the stock settings from the factory except I installed a Scotts Performance air/fuel adjustment screw in it. My bike had no issues with bogging. The only issue I did have was when I would pull the clutch in after riding awhile to stop, the idle would be high, I would have to slip the clutch a little for it to return to its normal idle. Not sure what was causing that.

Have fun, other than a windy Saturday morning, the riding was awesome.

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The only issue I did have was when I would pull the clutch in after riding awhile to stop, the idle would be high, I would have to slip the clutch a little for it to return to its normal idle. Not sure what was causing that..

Its called "hanging idle" caused by a lean condition.

Try turning down the idle a bit

Adjust the pilot screw properly

Check pilot jet for restrictions

Check for intake side air(vacuum) leaks

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Its called "hanging idle" caused by a lean condition.

Try turning down the idle a bit

Adjust the pilot screw properly

Check pilot jet for restrictions

Check for intake side air(vacuum) leaks

Thanks, I'll take a look at that.

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FWIW, I just got back from Glamis after riding my new 09 YZ450F. It has the stock settings from the factory except I installed a Scotts Performance air/fuel adjustment screw in it. My bike had no issues with bogging. The only issue I did have was when I would pull the clutch in after riding awhile to stop, the idle would be high, I would have to slip the clutch a little for it to return to its normal idle. Not sure what was causing that.

Have fun, other than a windy Saturday morning, the riding was awesome.

Hmm my 07 was doing the same thing on my first and only ride on it so far. I would stop like you said and the idle would be high. I turned my idle screw down though to compensate for that.

If it really was lean, then changing my main from a 160 to a 165 would help right? or would I have to adjust something else?

and thanks! Friday morning im heading out! Can't wait

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Hmm my 07 was doing the same thing on my first and only ride on it so far. I would stop like you said and the idle would be high. I turned my idle screw down though to compensate for that.

If it really was lean, then changing my main from a 160 to a 165 would help right? or would I have to adjust something else?

and thanks! Friday morning im heading out! Can't wait

The jet you are referring to is the main jet and has nothing to do with idle speed or air/fuel ratio below 1/4 throttle. The pilot jet is the jet for the low rpm fuel mixture. In addition to that if there is an air leak on the intake side the additional air entering the combustion chamber without the metering of the carb is what is causing the lean condition...not too small of a jet. More than likely you do not need to change your pilot jet. Start by adjusted the idle and pilot jet screws properly, check for intake side air leaks, remove carb and inspect pilot jet for any restrictions. 👍

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165/45 with the pilot 1 1/4 turns out works great for me in Glamis...

I think it should be run a bit richer than stock (I was with Sheridan thinking going from 160 to 165 makes it less lean, am I wrong about that?)...And not because of altitude, but because you ride the dunes pretty much wide open all the time under a heavy load until the gas runs out!

P.S. Zip Ty coolant helped greatly with overheating (another concern when in dunes)...Better than engine ice...

And you may want to look into the breather hose mod...When you bury your rear tire for a break, the stock breather hose rests perfectly on the surface of the sand, ready to suck some up when you kickstart...

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