2007 WR450 Colorado Jetting

[ddtoby]

Okay guys, 2007 WR450, I just picked it up, only 13 hours and it shows. Kid I bought it from did none of the free mods, bone stock. He did give me a GTYR AIS removal kit that he just never got around doing after he bought the kid. I plan on changing the throttle screw, removing muffler insert, removing air snorkel, removing AIS.

What jetting should I start off with the free mods. From what I have read, the ones in the GTYR kit are way to rich, especially at my altitude, 6000-10,000 ft. I asked the local bike shop, Grand Prix, where it was originally purchased, and they said keep what is in there even after the "free mods" are done. With my altitude and the mods done they said it should be fine. Any other opinions, I would rather not have to take the carb off muliple times.

Question is, what size jets should I initially run after the free mods at my altitude? Trails being ridden for the local guys are 717, rainbow, rampart, texas creek, taylor, etc.

Thanks.

[William1]

You forgot the grey wire mod.

Yes, at your altitude, the GYTR jetting will be quite rich. The free mods do not affect jetting though. The opening uop of the pea shooter has minimal effect on jetting, so little as to me a non-issue and at your altitude, a non-issue in the right direction. The snorkle too, may well make the stock jetting closer to being right. Of course, the only way to tell is by testing.

BTW, I do not consider the snorkle a free mod as most of the time, it requires jetting changes to compensate as most of us are at significantly lower altitudes. But for you, it probably does work out as a free mod!

[ddtoby]

Thanks. Sounds like I will just have to take a step at a time and do the mods first, ride it and see how it feels. I was just trying to get it done at once and be done with it. I was hoping to get a starting point so when I pull the carb off for the adj fuel screw and throttle stop I could change the jets at the same time. I will finish the free mods, including the gray wire and see how she runs.

[William1]

Changing jets on the bike is super easy. Doing the main, pilot and needle is a fifteen minute job.

Before you pull the carb to do the fuel screw (good idea as it is easy to loose the oring/washer spring when doing it on the bike) take the bike for a ride, confirm you do not have a bog during normal riding. I say this as you might need to chnage teh leak jet, it is mounted in the bottom of the float bowl and needs to be removed to access it.

[WR_Dave]

Thanks. Sounds like I will just have to take a step at a time and do the mods first, ride it and see how it feels. I was just trying to get it done at once and be done with it. I was hoping to get a starting point so when I pull the carb off for the adj fuel screw and throttle stop I could change the jets at the same time. I will finish the free mods, including the gray wire and see how she runs.

Try a 165 MJ a 40 PJ a "06 YZ jet needle on the 3rd clip from the top. THis should get you in the ball park along with all the free mods. Good luck - WR Dave

[Leardriver]

158 main in Denver, 155 at Rampart and all of the 8,000 and up riding areas. Dyno measured.