How do you know if rejetting is needed?


3 replies to this topic
  • jgerdi

Posted March 14, 2006 - 01:17 PM

#1

I live in Pensacola Florida so I am definitely at sea level with mucho humidity. I have an 06 450 LE . I have run 4-5 tanks of gas and it seems to run just fine. The only time I have questioned the jetting was on a cold 50 degree morning when it would pop on deceleration until it was completely warmed up.
I have a ziptie fuel screw on order but how do i know when it is adjusted just right?It sound like many 450 owners go to a 170/ 48 combo. how do you know that is correct?

  • Fastest1

Posted March 14, 2006 - 02:22 PM

#2

Well the best way would be with an O2/air/fuel meter. Besides that, a plug chop and tedious fiddling til you think it is better than it is now. Always keep notes as you make changes. There is no magic, it is all about experimentation. Experience might help you get there faster but you have to try something besides what you have now to see if it is right. When you get your new fuel screw, install it. Dont change anything else at first. Put it 2 turn out or where recommended by the maker, then tinker with it over the next ride or 3 and try 1/4 turn in or out and see if it feels different or starts easier. Winter temps run fatter jetting. Summer will require a different tune to be at its optimum and vice/versa. BTW record where your stock fuel screwis before removing it and set your new fuel screw the same way first. Then turn it in or out after riding it for a while. Always do your adjustments when the bike is thoroughly warm.

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  • Ga426owner

Posted March 14, 2006 - 02:41 PM

#3

I live in Pensacola Florida so I am definitely at sea level with mucho humidity. I have an 06 450 LE . I have run 4-5 tanks of gas and it seems to run just fine. The only time I have questioned the jetting was on a cold 50 degree morning when it would pop on deceleration until it was completely warmed up.
I have a ziptie fuel screw on order but how do i know when it is adjusted just right?It sound like many 450 owners go to a 170/ 48 combo. how do you know that is correct?


A lot of testing with different set ups.......trail and error....and a ton of patience :thumbsup:

  • ethan

Posted March 14, 2006 - 07:12 PM

#4

I don't know if those other responses answered your question or not, but I have an 06' and the stock pilot was a 42 and the stock main was a 165. I went to a 48 pilot (up two sizes) and a 168 main (up one size). I could tell it need to be re-jetted because the thing ran like crap when at idle. It would pop and puke just sitting on the stand. After the re-jet it ran much better. When weather gets warm the bottom end (pilot jet area) feels a little rich, but I can fix it with the fuel screw by going in (less gas for leaner mixture) a half a turn or more. This summer when it is always hot, I will go to a 45 pilot and leave the main. I live in Southern California.
Jetting is not that big of a deal and most of what you need to do can be accomplished with the main jet, pilot jet, and fuel screw. Motion Pro makes a carburetor tool kit for less than $10 that makes easy to change jets without having to move the carb. You need one of these if you want to fiddle with you jetting.
I hope this helps.
Ethan





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