08 Jetting woes


6 replies to this topic
  • CharlesFP

Posted March 03, 2010 - 02:20 PM

#1

I've never had more trouble jetting any four stroke I've owned than my 2008 YZ 450 F. Currently, I'm using an FMF jetting kit, and I've got a Leo Vince X3 full system. i usually ride between 2,000 and 5,000 feet of elevation. I'm not having any luck with anything I've tried. I'm having stall/hesitation at 1/4 to 1/2 throttle, as well as lot's of popping between mid and full throttle. I've also got a Boyeson Quickstart adjustable leak jet.

Since I've got lots of jets at my disposal, what's the optimum setting for Socal riding conditions between 2,000 and 5,000 feet?

thanks

  • Gunner354

Posted March 03, 2010 - 02:29 PM

#2

Get rid of the jet kit and after market acc. pump cover. Sorry but they r a waste of money. We run a 48 pilot, 1 1/2 turns out on fuel screw,richen up the stock needle one clip and run a 165 main. Runs well up to 7k elevation.

  • BlackT5

Posted March 03, 2010 - 02:51 PM

#3

I have a 08 with that same exhaust. I run 165-160 main, stock needle 1 clip rich, 45 pilot, 2 3/8 airscrew, and a 55 leak jet. Run about the same altittude in socal with ZERO issues.

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  • CharlesFP

Posted March 03, 2010 - 02:51 PM

#4

Get rid of the jet kit and after market acc. pump cover. Sorry but they r a waste of money. We run a 48 pilot, 1 1/2 turns out on fuel screw,richen up the stock needle one clip and run a 165 main. Runs well up to 7k elevation.


Going back to the stock accelerator pump may not be an option because I probably misplaced the original. Will it make a difference if I go to your recommended jetting specs?

thanks

  • ubu

Posted March 03, 2010 - 03:06 PM

#5

Mine is running pretty much the same way since adding a DRD. I changed to a 165 thinking the 170 was overly rich. I believe it was because it runs great on top with the 165. I checked the slide to make sure it was hole down and it was. Thinking about raising the needle 1 clip and it looks like I should from Gunner's post. It's still chilly up here, around 50 degrees. Think this is on the right track?

I also noticed some oily residue in the carb. I've been using NoToil and it may be that I'm pulling some oil from the airfilter, from over oiling maybe, or just that No-Toil isn't holding to the filter. But, I picked up a bottle of Maxima FFT. I don't like having to use solvents to clean the filter, but if it is truly a better filter oil (most swear it is) then I'll have to run it.

Also, I'm going to repack the silencer and use some sealant on the header to mid pipe joint. Exhaust header gasket is new.

  • grayracer513

Posted March 03, 2010 - 03:41 PM

#6

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  • Gunner354

Posted March 03, 2010 - 04:31 PM

#7

Mine is running pretty much the same way since adding a DRD. I changed to a 165 thinking the 170 was overly rich. I believe it was because it runs great on top with the 165. I checked the slide to make sure it was hole down and it was. Thinking about raising the needle 1 clip and it looks like I should from Gunner's post. It's still chilly up here, around 50 degrees. Think this is on the right track?

I also noticed some oily residue in the carb. I've been using NoToil and it may be that I'm pulling some oil from the airfilter, from over oiling maybe, or just that No-Toil isn't holding to the filter. But, I picked up a bottle of Maxima FFT. I don't like having to use solvents to clean the filter, but if it is truly a better filter oil (most swear it is) then I'll have to run it.

Also, I'm going to repack the silencer and use some sealant on the header to mid pipe joint. Exhaust header gasket is new.

As far as filter oil goes, I've seen some pretty scary filters that had a waterbased oil applied to them. Maxima or belray is all I'll ever use. Get yourself a 5 gallon bucket and lid. Fill it with about 4 gallons of diesel. Get yourself some rubber gloves and wash the filter in the bucket of diesel. Put the lid on when your done. Now clean the filter with soapy water to wash off the diesel and let dry. You can reuse the bucket of diesel for a very long time.





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