help me out here, will ya..


21 replies to this topic
  • soudry

Posted November 21, 2007 - 03:17 PM

#1

i have a stock 08 yz450 with about 2 hours on it, i'm in jersey, its about 40-60 degrees right now at about sea level, from reading, i get the idea that the bike comes jetted lean stock, i'm very new to 4 strokes and carburetors, any jeeting tips?whats a good way to know if the bike is lean? power wise i have nothing to compare it to.
when i let of the gas the bike doesn't idle right away it idle kinnda high for like 2-5 seconds and then idle at the right speed, how can i fix this?
or if i'm at nutral sometimes when i blip the throttle it will die on me. please help me out.
thanks for reading:thumbsup: :thumbsup:

  • todds924

Posted November 21, 2007 - 05:54 PM

#2

i have a stock 08 yz450 with about 2 hours on it, i'm in jersey, its about 40-60 degrees right now at about sea level, from reading, i get the idea that the bike comes jetted lean stock, i'm very new to 4 strokes and carburetors, any jeeting tips?whats a good way to know if the bike is lean? power wise i have nothing to compare it to.
when i let of the gas the bike doesn't idle right away it idle kinnda high for like 2-5 seconds and then idle at the right speed, how can i fix this?
or if i'm at nutral sometimes when i blip the throttle it will die on me. please help me out.
thanks for reading:thumbsup: :thumbsup:


Leave everything as is but try your fuel screw at 2 1/4 turns out.

  • soudry

Posted November 22, 2007 - 12:32 PM

#3

thanx i'm getting the fuel screw this monday

  • albertaguy

Posted November 22, 2007 - 02:36 PM

#4

JD jetting kits work great, easy to follow install. Colour inside head pipe and on plug is a good indicator of rich or lean - chocolatey brown is good, white is bad. Post with a better tittle in the jetting section and you'll get more advice than you can shake a stick at within the hour.

  • ubu

Posted November 23, 2007 - 08:24 AM

#5

or if i'm at nutral sometimes when i blip the throttle it will die on me. please help me out.
thanks for reading:thumbsup: :thumbsup:


My new 08 has about 1.5 hours on it. I had this same problem, thought it was kinda wierd. I also have some popping on deceleration, which I guess is normal to a point. It's getting colder here (high of 50 this weekend) I was going to try a 45 pilot and see what happens. I must keep reminding myself, "change only one thing at a time" or it will get missleading.

  • grayracer513

Posted November 23, 2007 - 09:49 AM

#6

> Colder weather requires richer jetting. A rough guideline is to increase one step for each 15 degrees drop (F). For instance, from a 165 to a 167 main, or a 42 to a 45 pilot. This only compensates for the temperature change. If your jetting was off before it got cold, it will still be off once compensated this way. If it was right, it will be right again.

> How the bike responds in neutral is going to be different than the response to get in gear because the CDI uses a different ignition timing map in neutral than in gear. Don't go by that.

  • soudry

Posted November 23, 2007 - 05:38 PM

#7

> Colder weather requires richer jetting. A rough guideline is to increase one step for each 15 degrees drop (F). For instance, from a 165 to a 167 main, or a 42 to a 45 pilot. This only compensates for the temperature change. If your jetting was off before it got cold, it will still be off once compensated this way. If it was right, it will be right again.

> How the bike responds in neutral is going to be different than the response to get in gear because the CDI uses a different ignition timing map in neutral than in gear. Don't go by that.


how is the menual jetting specs for cold weather?
i'll give that a try.
thanks agin for your help for the million time:thumbsup:

  • steve_97060

Posted November 24, 2007 - 10:27 AM

#8

FWIW... I just switched to my winter settings of 48 pj, 170 main on my 06.. was running 45/168....

  • soudry

Posted November 25, 2007 - 01:46 PM

#9

FWIW... I just switched to my winter settings of 48 pj, 170 main on my 06.. was running 45/168....


how cold is it by you?

  • steve_97060

Posted November 25, 2007 - 02:03 PM

#10

how cold is it by you?


generally in the 40's this time of year... we are at sea level also...

I had my carb done by Zipty last spring, I believe they recommended 45/168 when I had it done. It worked well. I ran the 48/170 last winter also, my bike usually starts on first kick every time...

I just changed over on friday, I reset the fuel screw to 2 turns initially, bike fired up first kick..

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  • rickallen124

Posted November 25, 2007 - 09:40 PM

#11

I'm at 800' with temps between 30-45 degrees and on my 08 I went from a 45pj to a 48pj and from the stock 160mj to the provided 165mj. Is the 165 going to be too rich? I have a 162 on the way and really don't ride unless it's at least 40f which may not be for a while. I hate the winter!

  • grayracer513

Posted November 26, 2007 - 06:54 AM

#12

What d'ya mean? Winter's the best time to ride! :thumbsup:

The 165 should be OK at 40 degrees, I would think. That's 30 degrees colder than the 70 degree baseline it was originally jetted for.

  • rickallen124

Posted November 26, 2007 - 08:07 AM

#13

Yeah, winter IS the best time to ride in California. Too bad I can't take a two month vacation to California.

  • soudry

Posted November 26, 2007 - 05:24 PM

#14

is it a real pain in the butt to change the jets on the 08?

  • grayracer513

Posted November 26, 2007 - 07:04 PM

#15

is it a real pain in the butt to change the jets on the 08?

http://www.thumperta...028#post5323028

http://www.thumperta...687#post5325687

  • todds924

Posted November 26, 2007 - 07:09 PM

#16

My new 08 has about 1.5 hours on it. I had this same problem, thought it was kinda wierd. I also have some popping on deceleration, which I guess is normal to a point. It's getting colder here (high of 50 this weekend) I was going to try a 45 pilot and see what happens. I must keep reminding myself, "change only one thing at a time" or it will get missleading.


08's come with a 45 pilot stock.

  • rickallen124

Posted November 27, 2007 - 08:23 AM

#17

If you get motion pros carb tool the jets are easy to change without removing the carb.

  • soudry

Posted November 27, 2007 - 05:59 PM

#18

i changed the main to day with out romoving the carb or any thing alse.
but for some resone its leaking fuel from the draining hose.
does any body know if a pilot jet from a 05 yz250 will fit the 08 450?

  • grayracer513

Posted November 27, 2007 - 06:32 PM

#19

If the pilot jet looks like the one in the first link I posted above, it probably will.

If you took the float bowl off, you may have bent or mispositioned part of the float assembly, or dropped the needle valve out of its seat.

  • soudry

Posted November 27, 2007 - 07:04 PM

#20

sorry for the dumb question but whats the needle valve ?
is it that white thing aroung the jets that came off when i took the main jet of?





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