07 YZ450 exhause pipe coler

5 replies to this topic
  • rtgincnm

Posted June 10, 2007 - 08:23 AM


Trying to dial in an 07 YZ450 riding around 7500FT and only change I have made is to change to a 158 main jet. The header pipe near the cylinder head is blue for about 6 inches and looks like it is quite hot when riding. My plug color is very light around the center and black around the outer edge. I have a little poping on decel but not much. Just don't want to run too lean. :thumbsup: Anyone else notice the color of thier pipe being blue?

Can't spell and can't type, you get the idea.

  • xcessjw

Posted June 10, 2007 - 10:05 AM


My 2004 450 has bluing of the headpipe for 6 or 7 inches and then it goes to a dull gold/brown at the mid pipe. I think the blue is pretty much standard fare as the head pipe is the hottest. If I run CAM2 or VP it makes the blueish even more pronounced. Also..dont panic if your head pipe glows orange when you let it idle a bit...totally normal.

  • grayracer513

Posted June 10, 2007 - 11:15 AM


My FMF Ti 4 turns blue clear to the can. It's the titanium that does it, and it's normal.

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  • bigred455

Posted June 10, 2007 - 11:28 AM


Do not jet by pipe color or plug color,you will be chasing your tail.The blue coloring of the pipe is normal,mine is a pretty blue:p by the tail end of the head pipe.Go by changing brass and pay attention to your motor after stepping up or down.:thumbsup: A 158 main in your altitude is bearly a change from the 160 with the 07.If you are rich on the main,and I still say you are with the 07,moving the main one step down is nothing.

  • rtgincnm

Posted June 10, 2007 - 07:23 PM


Thanks for the input everyone. I went riding today and the bike runs great. First time out in the desert after break-in, very impressed with the power and suspension.

The ride was at about 5500 ft. Need to check the plug to see how it was doing. Don't now any other way to get a feel how things are doing inside the engine since I don't have an EGT (exhaust gas temperature) gauge. Might be fun to play with one though.

Tried to lean out the air screw but did not find a spot that the RPM changed. Went about 1/2 turn in from stock, tried it, seemed like there was a bad flat spot off of low RPM. Left it set at 2.25 turns out from full tight.

  • nap__kxf

Posted June 11, 2007 - 10:15 AM


yeah the blue is normal. in fact, on my header the welds were a badass gold color after the first ride. but i jsut got back from pismo and all that riding turned the gold to blue. :thumbsup:

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