2007 YZ450f jetting for glamis


17 replies to this topic
  • Sheridan450F

Posted March 29, 2010 - 11:47 AM

#1

What's a good jetting for stock yz450f 07' at glamis? Which is basically sea level to 400ft above. My bike is in phoenix arizona at 1000ft above sea level.

  • grayracer513

Posted March 29, 2010 - 12:41 PM

#2

No reason to change jetting for a 600 foot change in altitude.

  • Sheridan450F

Posted March 29, 2010 - 01:31 PM

#3

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

  • rdefonce

Posted March 30, 2010 - 08:35 AM

#4

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.

  • grayracer513

Posted March 30, 2010 - 08:57 AM

#5

If you have stock main jet, you should probably go next size larger . . . I believe stock is 160 or 162, not sure though.

The '06 was delivered with 160, 165, & 170 main jets, with the 165 being most often installed originally.

  • rdefonce

Posted March 30, 2010 - 09:01 AM

#6

The '06 was delivered with 160, 165, & 170 main jets, with the 165 being most often installed originally.


Gray, thanks for those details. I bought mine used; didn't know that!
At least I got the manual with it.

  • Sheridan450F

Posted March 30, 2010 - 11:22 AM

#7

My main jet is a 160 ... Should I change it, and how do you get to it in less than 5 mins? lol

thanks

  • grayracer513

Posted March 30, 2010 - 11:29 AM

#8

Yes, go to the 165. Pull the plug out of the bottom of the carb, and use a 7mm socket to unscrew/replace the jet. Don't over tighten.

  • Sheridan450F

Posted March 30, 2010 - 11:33 AM

#9

K, will I have to mess with the pilot screw adjustment at all? Idle? And stupid question but what is this carb called, lol :thumbsup: Is there a good thread with pics? The manual sucks

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  • grayracer513

Posted March 30, 2010 - 11:42 AM

#10

You might have to do that, but not on account of the jet change. The carb is an FCR-MX (that's in the manual). Read the links in Common Threads regarding pilot adjustment.

  • Sheridan450F

Posted March 30, 2010 - 02:07 PM

#11

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

  • husky390or

Posted March 31, 2010 - 05:06 PM

#12

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.

  • JandJ07

Posted March 31, 2010 - 05:29 PM

#13

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

  • husky390or

Posted March 31, 2010 - 05:33 PM

#14

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.

  • Sheridan450F

Posted March 31, 2010 - 06:09 PM

#15

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

  • JandJ07

Posted March 31, 2010 - 06:31 PM

#16

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. :thumbsup:

  • grayracer513

Posted March 31, 2010 - 07:06 PM

#17

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.

More like 1/8th throttle, but otherwise accurate.

  • Aka.Goose

Posted April 03, 2010 - 07:54 AM

#18

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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