jetting question

[YFZ450Ridr]

yes i did a search and didnt find anything helpful..

anybody have an idea of what i might need for jetting with..

stock 36mm carb
uni filter with outwears
white bros e series slip on - 12 discs
airbox lid off

im not sure what current jetting, guy never told me(im takin current jet out tomorrow and ill know). but i want to take my airbox lid off and was thinking mabye a 160 main? should i keep stock pilot jet and should i mess with the air screw any? any help at all appreciated.

[kawai 521]

I have a 05 kfx. I tried a 140 main, it was a little to much, so i dropped to a 137.5. It works perfect. Also if you want to modify the airbox, i would just cut a 3 inch hole in the top, where the air channel is. Runing without one could lead to alot of motor probs. You could get dirt inside of the motor and ruin your valves and possibly sieze the piston. hope this helps

[rmz250]

i thought your lid is already off?

Well Mikuni and dyno jet jets are completely different. Here is the chart...

Mikuni--Dynojet
140-----149.3
150
142.5---152.0
145-----154.7
155
147.5---157.3
150-----160
152.5---162.7
165
155-----165.3
157.5---168.0
170
160-----170.7
162.5---173.3
175
165-----176.0
167.5---178.7
180
170-----181.3
172.5---184.0
185
175-----186.7
177.5---189.3
190
180-----192.0
182.5---194.7
195
185-----197.3
187.5---200
190-----202.7

When I had my Kfx I ran 155 dyno jet, Needle 3rd clip, 2 1/2 turns on airscrew, and I had a full hmf exaust , twinair filter, and no lid. My friend runs this set up on his z and it runs great. I'd check with the chart up there and see what the 155 is compared to in mikuni if your running mikuni jets. You prob gonna be at a 145 mikuni main jet. I run everything I got a little lean also. If you need anymore help just ask away.