04 WR450 Jetting ?

[SCRC John]

I've searched and can't find any info specific enough for my situation. I'll shake it down for you guys:

2004 WR450

Stage 1 hot cams

AFE Dry filter

Pro Circuit Ti Full System

Barnums Pro Air Box Side Cover

I'm 3 turns out on the FS

52 Pilot

175 Main

One up richer needle on the middle notch

BTW I'm in South Texas (Houston area) so pretty low SL & VERY humid:bonk:

Gray wire mod

Coaster valve blocked

If I am leaving anything out please ask. The bike feels pretty good off the bottom, but stutters pretty bad north of 6K. Esspecially at steady throttle.

[TLRam1]

If it's stuttering you are too rich, need to lean it out and it's not so much at what RPM as it is to where your throttle is at.

I don't have what you have in mods but I am running a 170 main, stock needle position and one larger pilot jet.

What happens at WOT?

What other jetting have you tried?

[SCRC John]

At WOT, it actually pulls pretty good. As soon as I back off of WOT, say 3/4 throttle then the shuttering starts.

I've also been playing with the fuel screw and have come to the conclusion that my Pilot is still too small. I have a 55, I'm going to throw that in tomorrow. I know that it does not directly effect what is going on, but I would feel better with that issue ironed out.

BTW The changes that are currently listed were changed from stock. I added all of the mods to the bike and thus now am playing with the carb to get everything working right.

[ww44wrf450f]

I think you are runnin a little fat?

168 - 170 main

48 pj

check out the jetting sticky?

[TLRam1]

When you jet a carb you work down from WOT to midrange than to bottom end. I don;t know how radically or where the help comes from a Stage 1 cam.

I would reference the above jetting as a starting point and go from there.

Why do you think you need a larger pilot?

One thing is the terminology "Stuttering" or "babbling", does it cut out or is it a steady run but can't get any RPMs (haha, I know I'm not doing a good job with descriptions myself), still sounds like you need to drop the needle back down and lean it out a bit.

[CanadianWR450]

Your settings sound rich....

I have a 04, Canadian model (no grey wire, already has YZ throttle stop), stage 1 Hotcam's, air box cut outs, FMF Ti Powercore.

I'm in Atlantic Canada, around sea level, and way cooler here then in Texas with less humidity.

I'm running stock pilot, fuel screw around 1.5 out and adjust for conditions, and a 170 main with JD Jetting set to YZ specs (Needle one notch richer is the only difference between the WR and YZ settings)

[SCRC John]

Your settings sound rich....

I have a 04, Canadian model (no grey wire, already has YZ throttle stop), stage 1 Hotcam's, air box cut outs, FMF Ti Powercore.

I'm in Atlantic Canada, around sea level, and way cooler here then in Texas with less humidity.

I'm running stock pilot, fuel screw around 1.5 out and adjust for conditions, and a 170 main with JD Jetting set to YZ specs (Needle one notch richer is the only difference between the WR and YZ settings)

According to Sudco, the YZ needle is different than the WR needle. I'm running the YZ needle (richer needle) 3rd notch down from the top.

I've reset the TPS, installed the 55 pilot as well. It starts WAY better. The surging or shutter is still there above 6K. Better, but still there. I'm going to try and richen the neddle up one notch.

I've also noticed the surging is not as bad in 5th gear. Could this help piont to any conclusions? I'm thinking it has something to do with engine load, but I'm not linking it all together in my head.

[CanadianWR450]

"According to Sudco, the YZ needle is different than the WR needle. I'm running the YZ needle (richer needle) 3rd notch down from the top."

I'm running the JD needle....

I still think your to rich on the main....I'd try a 168-170....given your area and conditions...I'd try the 168 over the 170.......

I would do this before richening the needle. I do not think your to lean there.....you leaned out the bottom, and it helped....so now lean out the top...your problem is starting when your starting to get into the area where the main starts to kick in.....

[drtbk4ever]

I think you are WAY too rich, especially the pilot. I would go back to a 48.

Remember high temps, need leaner. Low temps need richer.

Low elevation, need richer, high elevation need leaner.

As suggested it isn't RPM it is throttle position that determines the jetting circuit you are in. When you got it cranked u are on the main and it is humming. But when you back off the WOT, you likely move back into the pilot circuit which is WAY rich.

Here is a link to Eddie Sisneros's thread on how to set your pilot circuit.

Follow this.

https://www.thumpertalk.com/forum/showthread.php?t=327405

Re: the stuttering/blubbering. You can minimize this via jetting but chances are you will never be able to eliminate it. The TPS can add to this as well as the CDI. However, incorrect jetting just excacerbates the issues.

Do a search on jetting in this forum and the jetting forum. Read read read. There are plenty of people that have the same issues you do.

Please keep us posted.