250-500cc 250 / 300 / 360+ Jetting Database

I Love it. I had probs with the top end loading up and needing to clear out, but not anymore with the 160. Bike runs great, pulls strong, lugs low, and I have even received compliments that it sounds great and sounds like its jetted perfect!!! I love Bel Ray H1R too!! Burns clean and is super easy to use their bottle. One bottle to five gals = 50:1, 4 gals =40:1. I haven't used the Ratio Rite in a long time.

Year & Bike Model = 2009 WR300

Carb = 86mm Keihin PWK

Pipe & Silencer = PC plat II and 296 sparky

Other engine mods = none

Premix ratio & fuel type = 40:1 Klotz R50 w/ Chevron 91 octane pump swill

Temperature range (deg F) = 65-70

Elevation (feet) = 8,000'+ ASL

Main jet = 165

Pilot jet = 42

Needle = CEL

Clip position = #2

Air screw setting = 3.0+

Slide = ?? whatever the carb came with (from 99' CR250R Honda)

Pilot is still fat and bike feels lazy down low, but once into the mid and top it feels crisp and powerful. It needs a 40pj or maybe even one size smaller (do they make a 38pj?)

Bike still makes quite a bit power at this elevation, but I can most certainly feel the power loss vs. home (sea level - 2500'). It's kinda fun though cause I can never hold the 300 open like I can here!

I haven't checked mileage, but I think I'm burning more gas at elevation than I usually do at home. I thought the smaller jets and less oxygen would require less fuel to burn, but I guess not.

Hi all, finally was able to check the carb & jetting on the '09 300. I'm at sea level (floriduh) with the Mikuni
Main- 430
needle- stock(I think, probably need new magnify glasses to see) in 3rd pos
slide- 4.0
pilot- 40
air screw- 2 1/2

Seemed to run great at the PA Nat'l, only problem being hard to start when stalled, which happened often. I'll know better when I ride it here, thinking maybe a 35 pilot.

Year & Bike Model = 2009 WR300
Carb = PWK
Pipe & Silencer = Stock
Other engine mods = None
Premix ratio & fuel type =Ipone 40:1 , Supreme
Temperature range (deg F) = 15-20 deg C
Elevation (feet) = 500 ft
Main jet = 178
Pilot jet = 40
Needle = CEL
Clip position = #2
Air screw setting = 2.5 turns
Slide =
Conclusions/Results = Revs clean from idle up, nice low-mid range, crazy top end. JD red needle in #3 produced linear steady power, however with the CEL the top end is just massive.

Year & Bike Model =2009 WR 250
Carb = MIKUNI
Pipe & Silencer =HUSKY RACING
Other engine mods = NONE
Premix ratio & fuel type = AMSOIL DOMINATOR 32:1
Temperature range (deg F) = 50
Elevation (feet) =STAGING AREA1700FT TO 5800 FT
Main jet =400
Pilot jet =30
Needle = 6bfy4374
Clip position = 2
Air screw setting =1.5
Slide = STOCK #4
Conclusions/Results =IDLES GREAT RUNS CLEAN. FEELS GOOD EVEYWHERE.NO SPOOGE I THINK I'LL CHANGE THE MAIN JET TO A 410.PLUG WAS DARK BROWN.

Year & Bike Model = 2010 WR 250
Carb = Stock Mikuni TMX38
Pipe & Silencer = Stock
Other engine mods = n/a
Premix ratio & fuel type = 50:1, 93 octane pump gas
Temperature range (deg F) = 40-60 deg F
Elevation (feet) = 500 ft
Main jet = 430
Pilot jet = 40
Needle = 6BFY43-74
Clip position = middle
Air screw setting = 1.25 turns out
Slide = 4.0
Conclusions/Results = Only changes from stock were 40 pilot from 35 and 430 main from 460. Lugs better down low and rips up top. There is a bit of a hit when it comes on the pipe now. It is definitely harder to handle where there is low traction now when it hits. If I can't adjust to it I will go to a 440 main to detune it a little. Otherwise I will probably try a 420 when the weather gets hot again.

Anyone try the Power Now or Boyesen carb inserts with their Keihin and have experience with any jetting changes they require?

HRC 630 here at the forum use the Powernow and he likes it alot!

I just want to say I have used products like that in two other bikes I owned. One a KTM 2 stroke and the other a Yam 4 stroke and this is only a subjective (my own feeling about it) opinion, but I am quite sure both of those bikes were the cleanest running bikes from the bottom up through the mid and worked better than the other bikes I have owned on the trail.
Another comment: The Power Now system effectively reduces the carb bore size. The 38mm I am using, is going to be more like a 36mm and that is fine.

I recently changed my pipe to a FMF Gnarly and after the switch it was immediately obvious that the main was too rich. All the other circuits are pretty close as they are listed above but I leaned out the main to a 390 and backed out the air screw an 1/8 turn from where it was. The Gnarly made the power much usable, the bike still pulls as hard if not harder but smoothly and the big bonus is it tops out like a 125. The FMF is definitely worth the money and I'll bet that the turbincore silencer would make the bike fly but since I need a spark arrestor for most of my riding it's not at the top of my list.

Year & Bike Model = 2011 WR300
Carb = Mikuni
Pipe & Silencer =Stock
Other engine mods = none
Premix ratio & fuel type = 50:1 Maxima 927 91 Octane pump gas
Temperature range (deg F) = 45-70 degrees F
Elevation (feet) = altitude is usually between 500ft and 2500ft
Main jet =420
Pilot jet = 45
Needle = "GAY"
Clip position = 3rd clip
Air screw setting = 1 1/8
Slide = stock??? it says 5 on it and everyone talks about a number 4 slide

Bike starts and runs great. I'm happy.

Steve

Year & Bike Model = 2010 WR300
Carb = Keihin
Pipe & Silencer= Stock Expansion chamber, Leo Vince
Other engine mods = none
Premix ratio & fuel type = 50:1 Dumonde Tech
Temperature range (deg F) = 55 degrees F humidity 90%
Elevation (feet) = Altitude is 150ft where I live. I usually ride at 800 to 4000ft. In the summer I ride all the way up to 7700ft.
Main jet =175
Pilot jet = 42
Needle = JD Red
Clip position = 2nd clip
Air screw setting = 1 1/2
Slide = Whatever JD puts in.

My bike seized on this jetting.

Anyone got specs for an early 360 with a 38 PWK airstiker?
Stock expansion and muffler.
Sea level to 1000 feet.

Stu

Walts specs are on page one

Rides between 1000 & 4000

Stu,

I have a 96 Wr360 and my mate has a 92 Wr360.
These are my and his settings for a PWK 38mm and we operate from 10mt to 1000mt+ using the air screw as the only adjustment:
96 Wr360
JD Jetting Red needle set at middle clip
no.7 slide
38 pliot
175 main
1.5 to 2 1/4 turns out depending on the altitude and heat.
92 Wr360
JD Jetting Blue needle set at 2nd from the top clip
No. 7 Slide
40 pilot
172 main
2 turns out.
I like to ride the 360 in more ST's whilst my mates 92 likes more the open stuff with occasional ST's plus he likes the response from mid to WOT og the blue needle.

I haven't tested/used the Keihin spec needle but it seems the DEL and EEL are the ones to try.

Haven't fouled plug in two years and only changed one recently after l did the top end...also using the std NGK BR8ES gapped at .50mm.

Brilliant mate, thanks heaps, will give them a crack!!

Stu

I have looked but can't seem to find the answer...

2011 WR300 Stock carb, pipe and silencer..
no modificatins to air box
Maxima Super M at 40:1 0 - 1500 Above Sea Level
(sometimes higher)

Any jetting recommendations????

Thanks