"RED" hot header??

Just purchased a used 2005 WR450...the last owner stated that the bike is jetted for high elevation up to 9000ft...I live in 2500ft area and will ride up to about 6500ft...the valves are titanium, new cam and piston...not sure what he put in because the mechanic has the sheets.(still in the process of access these)..the bike also has FMF pipe with power bomb header...the jets in it are as follows:

Main 165

Jet needle adjustable on 3rd clip

Pilot jet 48

Pilot air jet??

Starter jet #65

Leak jet #50

The bike he states is very high performance (since it was to be used for a desert race) and will burn up if I try to run it at my elevation...he had 103 octane fuel in the tank when I bought it last week..anyways during my mechanical check on the bike I removed the BAJA 4 gallon tank and all the fuel leaked out overnight (don't ask how... that is not the point here:banghead: ) I filled up the bike with our canadian premium at 91 octane...started the bike and in about 4-5minutes idling the powerbomb is glowing red hot...

The bike runs fine..doesn't do the lean revving when opening the throttle (open the throttle..then close it..the revs drop with the throttle and don't get "hung up" as in a real lean situation)..the bike starts easy but the header glows red...I moved the needle jet to the middle clip and I know that has hardly anything to do with the idle but I tried it and it runs red hot again...(needle jet is for more at 1/4 to 1/2 throttle)

Any suggestions...I put a bigger main in at 180 still the same...so does the pilot have to be bigger ie.60 or 65 from a 48..maybe a smaller pilot air jet??? not sure but any help will be very appreciated...

I am wondering if race fuel at 103 will make the bike run cooler???

All this is at idle no driving at all...bike is very snappy at the throttle no bog just quick response...not sure of the cam put in?? The AIS has been removed..has a high flow air filter as well...

The carb has been taken off a cleaned throughly...pilot jet is not plugged ..blew cleaner through it and aire ...all openings are clear...fresh fuel and all that..thanks

At an idle they do get red hot once you start moving it should cool down.Are you doing the idle thing in the dark thats the only time most people notice the header pipe glowing.

This is done in the garage...I have been searching this site and found a number of posts on this subject..i am sorry if I am going to get a few guys wild again...will the hihger octane fuel make the bike run cooler or has anyone ever tried a very large pilot jet???


I think the race fuel makes it run a little leaner if I remember right I am going off of when we used to race cars.Maybe thats why its running a little hotter too.Just my .02 cents

I just purchased an '06 WR450F and noticed the same "Red" pipe when it was idling. After a short journey it returned to a more normal colour.

Thanks for the help guys...race fuel definelty helped out to run cooler..also installed a #50 pilot jet....and adjusted the fuel mixture screw...all fixed up...

now waiting for the snow to melt for a rip!!!!

Hey Whacker, where in Alberta are you located.?

I am surprised you needed to go up to a 50 pilot jet, but perhaps that is due to the mods the previous owner completed.

I live outside Edmonton and run a 48 pilot, but I am still using the stock exhaust. I am gonna try a YZ exhaust on it in the spring (or maybe when it hits plus 10 on Xmas day:thumbsup: ). So I'll follow your lead and have a 50 pilot on hand just in case.


The red pipe is normal....the 103 octane will not make the bike run cooler, or hotter, and it's a waste of money. The 91 octane is fine. Letting the bike idle that long without moving, is a no-no, as per the shop manual. You need to be moving to get air through the radiator. I'm guessing with idling that long, you were boiling coolant into the reservoir. As for the higher octane fuel...if you're not getting pre-ignition ping, stay with the 91. You don't get "more power", by using the higher octane stuff. All these subjects have been covered in-depth here before. The search feature will get you to the threads that'll get you more information, if you need it. Enjoy your bike bro....she sounds like she's a screamer...

I am located in Medicine Hat...

The last owner had the motor blue printed, new cams, piston, titanium valves, done on the bike...I am still waiting on that paper work of exactly what was put in...thanks for for the 103 octane information...makes sense and once the snow melts here it is time for a rip...I will keep everyone posted...

as for the 50 pilot jet...I am sure it will work well by adjusting the fuel mixture screw...

Thanks for the input and patience guys and gals!!!


How Many times?

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