YFZ450 Jetting Recommendation [Archive]

onefast400ex

04-12-2007, 09:26 PM

Hi
My yfz has an HMF slipon. My carb has a boyeson quick shot and I just ordered the modquad K&N air flow system. Does anyone have any experience with a similar set up. What Jetting would you recommend.

Thanks a lot for your help

TWILES

04-14-2007, 11:44 AM

I have a 2005 WR450 and it looks like to me that if you will change to the stock YZ needle(NFLR) in the 3rd clip your jetting would change a little and might make a little more sense. There were BIG differences in some of those. The WR's have a little bit different carb than the YZ's. I don't know which carb the YFZ's have but after looking at the jetting some were using I'm assuming the the same as the WR carb. The way to tell is to look on the left side of the carb and if there is a circle sticking out with a couple of screws holdng a cover on, it the WR carb and this should work. If not, this will be way too rich.

main would be around 168
Pilot would be 45 or 48
Fuel screw would be between 1.5 to 2 turns out.

Thats a good all-around jetting for a WR450. As far as I know the head castings, valves, and intake cams on all the Yamaha 450's are the same (up to the 06 YZ and 07 WR) and exhaust cams don't change jetting. So with a slip-on muffler and lid off the airbox, that carb set-up shoudl work with that needle.