I have changed the jets using the advice given by UTVOLS, 48 pilot, 160 main, 72 starter, and it runs much better, but I still have a little hesitation right off idle. Any suggestions would be greatly apreciated! I'm at 500 foot elevation.

Thanks, Jeff

i had the same problem but once the bike warms up it goes away. try letting your bike sit for a while to warm up than ride it and see if that helps.

I am pretty happy with this jetting but do not feel it is the perfect answer at this point. I will be experimenting with some different needles and will let you know what I come up with. In the mean time play with your fuel screw & needle clip to see if you can make it any better. I have tried the YZ needle and it was better but I did not like the top end power.

Until we find more people willing to experiment we are just going to have to be patient.

UTVOLS, thanks for the help. I will try moving the needle around and changing the mixture and then report back to you guys.


160 main seems a bit fat here in okc 1100 feet 50 degrees changing to 155 main

I have the same bog on low end with a 48, 160 combo. Is the bog because it is rich or lean? Should I go to a 50 pilot or move thge needle?

Any answers?

Using the 48, 160 combo and have a bog on bottom. Is tis lean or rich? Should I go to 50 pilot of move the needle?

158 main works excellent here on the Gulf Coast with its high humidity and warmer temps. I haven't zeroed in on the pilot yet..


I am using "utvols" jetting also down here in Medford without the 72 starter jet "because my order hasn't come in yet" But I also have the Power Now. I was in Christmas Valley for the last four days and it was a little chilly over there. I had to use the choke to start the bike every time, even if if it had only been shut off 2 minutes. I think that the 72 starter jet would help that out a bunch. I don't seem to have any bog anywhere, it just goes like hell. Starting is my only issue.


Hey Jim,

Glad to hear you are out riding! I did 60 miles in Millican Valley. Sand whoops forever! The 72 starter jet does help with the starting. Tell me more about the Power Now. Did you make your own or buy the complete system? Do you have a web site for them?



When I get the YZ neddle I am also going to put a #100 PAJ in to see if that helps. I would reather loose on the top end , than have the off idle bog.


I bought the genuine Powernow from a shop there in Eugene called Cycle something or other. I can't remember what. I will check my Visa bill tonight because I got the bills for bike stuff yesterday when I got back to town, I'll let you know tomorrow.


I put a 160 main, 48 pilot, and turned the air screw out a little. It runs a ton better but still has the same little bog every one is talking about, and it also back fires when I'm decelerating. I always thought that was a sign of rich jetting. True or not? I tried turning down my accelerator pump but the bog got worse especially when I really get on it out of a turn or jump face. I'm putting the pump back to stock or maybe even a little richer. That still won't fix the back fire though. That may be something I'll have to live with.

I checked the plug after last weekends 40 mile hard ride and it looks good. Not white or dark, just a nice crisp brown.


I got the Power Now from "Cycle Buy .com. Their phone number is 995 7709. and it's right there in beutiful downtown Eugene or close to downtown.


Thanks Jim, I will go pick one up!


Nice to see other WR450 riders in this area of the woods. I too have done most of the mods on this forum and have the same hesitation off idle. I would be interested in any new ideas on this problem.

I changed the pilot screw from 2 turns out (stock) to 1-1/2 turns out, set the stock clip to 5 richer, and changed the pump screw by 1/2 turn out. Started it and it backfires when goosing it in neutral. Still raining can't ride yet, so don't know if that helped the idle. will let you know. I know that is a lot of changes at one time!

I have found that backfiring during deceleration is caused by LEAN pilot jetting. I'm running 155 main, 48 pilot, everything else stock. No backfires.

After race last weekend, (high speed course, 40F temp, central Texas) I feel I need more top end power. I haven't pulled my plug to check color, but I think I need a larger main. Will also move clip in richer direction and get a 72 starter jet.

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