GYTR Jet Kit vs. JD Jet Kit

24 replies to this topic
  • BajaFool

Posted January 08, 2009 - 09:15 PM


The OBDWR Needle is the standard needle for the 2004 WR50F (note part number and description from the Yamaha parts manual in my earlier email).

As I stated in my earlier email, one variable at a time. When you install all of those after market add-ons at one time in an attempt to change/improve the carburetor characteristics you will just have an impossible situation to sort out if the bike begins to run badly.

Regarding the bog off of idle. At 2 1/2 turns out on the Air/Fuel Screw, you are "according to the book" at the point of requiring the next size larger Pilot Jet (#48). The Pilot Jet affects off idle to 1/4 throttle, the needle and main jet generally do not. You may want to carefully re-check the Fuel/Air Screw adjustment, to ensure that it is adjusted correctly. Changing the Pilot Jet to one size larger is not the end of the world --- it just seems that way when you have to work on the carb on these aluminum framed Yamahas.

My bike is at 2 1/4 turns out on the Fuel/Air Screw and I am satisfied with the throttle response off of idle. I don't plan to go with a larger Pilot Jet. I have ridden my current bike (2008 WR) from the front wheel on the high tide mark of the Pacific Ocean to 3,900 ft with outstanding throttle response and great gas mileage (40 MPG). My 2006 WR used the same jetting from sea level to 5,500 ft with equally good throttle response and gas mileage.

The other variable in this equation is the after market pipe. It could and probably will have an effect on your jetting. I can't comment on what that effect would be, however. I would not recommend installing the new exhaust system parts until you have solved the bog problem.

I did not change the Leak Jet in any of my motorcycles, they run just fine with the standard jet. Here is a ThumperTalk link about Leak Jets

  • BajaFool

Posted February 17, 2009 - 04:34 PM


I could not send you a private message. Error was "your mailbox is full, delete some messages". Here is the reply to your private message.

I apologize for the confusion. Yes, you count from the top or blunt end of the needle. Thus, as you move the clip from the #4 to the #5 notch you raise the tapered needle higher in relation to the constant diameter of the Needle jet. This allows more fuel to flow into the engine causing a richer fuel/air mixture upon combustion.

Don't get discouraged. Working on jetting builds character.

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  • JWW

Posted March 12, 2009 - 11:04 PM


I have the following mods done to my '07WR450

1) JD red needle on the 4th clip from the top
2) 168 Main
3) 48 Pilot
4) I used the other jets in the JD kit as well which I believe was a new leak jet but not sure
5) Snorkle removed
6) AIS removed
7) FMF Powercore 4TI slip-on
8) Throttle stop replaced

I ride from the CA desert at 2,500' to the mountains at Kennedy Meadows which got to 9,500' and I didn't make any adjustments. It has ran great with no bog or popping in any condition

I had all of these mods done before I ever rode the bike so I don't have a baseline to compare the performance to. For me, I have been very happy and haven't thought about tweaking it at all.

We seem to ride similar terrain. i bought the GYTR tips instead of new pipe but everything else is the same. Going to copy your set up and see how it feels. DId you do the O ring?

  • KennyMc

Posted March 13, 2009 - 08:31 AM


We seem to ride similar terrain. i bought the GYTR tips instead of new pipe but everything else is the same. Going to copy your set up and see how it feels. DId you do the O ring?

Oops, sorry I left that out. Yes I did.

  • akiraone

Posted July 31, 2009 - 03:41 PM


Hi I dont want to open new thread thats why I ask you here for some help with my jetting.

I live in Poland (Elevation around 1000ft, temp. 75-90 degrees)
I have WR450 2006'
I have tryed with many setups from
-165-168-170-175-180 Main Jet
-42-45-48-50 Pilot Jet
-45-50 leak jet
-and the needle I cant remeber right now all signs on it but for sure first one was with the letter "Q" on the end i try from 3 clip and 4 clip and the second one is with the "R" and also i try with 3-4 clip.
-i try with from Fuel Screw Sunline and Stock

my problem was always hard to start when the bike was cold let say it wasnt used for one day. I have to kick 7-8 times until in runs. but after it warmed it was working fine maybe the idle wasnt steady but I get used to it. The bike runs pretty hard I could even pickup front whell on 4th gear. but some of my friend when tryed to ride on it they sayed it to rought but I was all the time thinking its because of my exhaust "higashi"

ok anyway on this time I have this set up
- Main Jet 170
- Pilot Jet 45
- Starter Jet 65 Stock
- Air Jet 80 Stock
- Leak Jet 50 Stock
- Needle this one with letter "Q" on the end 3 clip from top
all mods done (gray wire, AIS removed, oring, exhaust)
I didnt count how many turns in fuel screw

Then I disamble it repack everything from beggining
- Main Jet 175
- Pilot Jet 50
- Leak Jet 45
- Needle "Q" clip 3
other STOCK
- fuel screw 2 turn BUT ITS REALLY DOESEN'T MATTER because even if I turned it all the way IN bikes run the same as all the way OUT.
Results bike starts just by one turn of crank. Works pretty smooth nice and steady, when I hit the throttle pretty fast on idle it dosen't bog or something.but when I take it for a ride it was smooth but now power I barely could wheelie on 2nd gear.

and after this I have tryed everything diff. Main, Pilots Jets nothing could helped with my fuel screw I could turn it all the way in and the bike was running the same only the I turned almost it all the way out its starts slow idle speed down.

and after many tryes I ended with
- Main Jet 165 (stock)
- Pilot Jet 42 (isnt it to lean ???)
- Leak Jet 50 (stock)
- other stock
- needle with "R" on the end and 4 clip from top
- fuel mixture 1.75 turned out (and now I started have a sympthons when I turn all the way in that bike start to stall. but I strange for me that I have to go with all the jets to stock and even with pilot jet leaner. and I have problem right now when I hit the throttle on idle pretty fast its bog or stall.

When I look in other thread most of people (with simmilar altitude and temp. and the same bike) have to go with pilot jet up to 48 to run the bike good.

please could you give me some advice should I stay like this or maybe I did something wrong before my adjustments. and what about this when I hit the throttle that bike stall.

sorry for my english grammar.



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