Jetting Help

[Braz]

I installed the JD Jetting kit on my WR450F and went riding today. The bike just ran crappy overall. It seemed to bog down a lot and ran real rough. The engine breaking seemed to be worse than usual also. I have done the grey wire mod, removed the airbox snorkel, removed the AIS stuff, and installed the JD Jet kit using the blue needle with the clip in the 4th position and the 170 main jet. I live in Texas so elevation is less than 1500 ft. It was pretty cool today, started out in the mid 30s and warmed up to the upper 50s. Any suggestion on what combination I should go with would great.

Thanks,

[clark4131]

Do you have a 48 pilot or the stock 45? With your elevation and cold temps, you should be running a 48...SC

[rich1167]

Here's the part of Indy's chart that applies to you. I used it as a baseline and only had to adjust the needle position to dial it in. Defiantly look at your pilot and leak jet to help the bog. Your leak should be a 50 stock. I would also install the Zip-Ty fuel screw so can adjust it on the fly. If you haven't uncorked the exhaust you need to do that.

Elevation 0 to 4,000. feet

30 to 45 degrees: 172 main, JD Blue #5, 48 Pilot, 2.0 turns, 75 starter jet, #0 leak jet

45 to 60 degrees: 170 main, JD Blue #4, 48 Pilot, 1.75 turns, 72 starter jet, #0 leak jet

[YamahaWR450FMike]

I did the JD jetting on my 2004 WR450 and worked awesome first time. 48 Pilot, Blue needle 4th postion and 168 main. Made a huge differance in performance over all!

[Braz]

What is the stock pilot jet and starter jet? I did uncork the muffler and my Zip-Ty just came in the mail today but I have not installed it yet.

[rich1167]

I think the stock pilot is a 45 and the starter is a 70.

[YamahaWR450FMike]

yes stock is 45. I left my starter and leak jet alone.

[rich1167]

I also left my starter jet alone. I don't think the starter has much if any thing to do with performance. I was out not even fully warmed up today about 40 deg OAT and pulling strong wheelies off idle in 1st and 2nd with no bog.

Elev: 4500 to 8000

30 to 55 OAT

168 main

48 pilot

0 leak

1 1/2 fuel screw

JD blue 5th pos.

[Braz]

Thanks for all the suggestions. I am going to pick up a 48 pilot jet and 0 leak jet. Would these same settings work on an 04 YZ250?

[Flaminchiten1967]

Don't forget to do the throttle stop mod also

[Matty05]

Thanks for all the suggestions. I am going to pick up a 48 pilot jet and 0 leak jet. Would these same settings work on an 04 YZ250?

NO............

the 250's emoltion tube is not as efficient and bigger mains are required rather than smaller. They don't need as much fuel as the 450's.

WR's also have ACV circuit which screw jetting around.

You have to do the throttle stop mod (just buy a yz one). If you don't have this done, this is why your bike is crap.

[Braz]

I had the dealer remove the throttle stop but I don't know if they changed the throttle screw to the YZ (I don't think they did). I have a YZ throttle screw but I have not put it in yet. I have to find where the old one is so I can change it but I can't find it in the carburetor schematic.

[Braz]

Ok, I have been calling all over trying to find a #0 leak jet. Everyone is telling there is no such thing. Where do you get one of these?

[rich1167]

Pick one you will never use and solder it closed. Go out and buy a #70 and solder it closed. I think someone on here may have a part # for the 0 but I don't know it.

[Matty05]

I had the dealer remove the throttle stop but I don't know if they changed the throttle screw to the YZ (I don't think they did). I have a YZ throttle screw but I have not put it in yet. I have to find where the old one is so I can change it but I can't find it in the carburetor schematic.

pull the side plate off the right side of the carb, where the throttle cables go into. you should see it to the back of the carb. If you can't, just twist the throttle and see what is stopping it!

If the dealer changed the throttle stop, this is it!

There is no throttle screw..... you have been mistaken. Don't worry about it.

Take it out and measure it anyway. if it is over an inch long before the head of the stop, it is the wr one. the yz one is less than an inch long (not including the head).