Check this out!!!!!

Not good. This is a picture of my exhaust. It was only running for about 45 seconds. To make a long story shorter than it could be, the idiot (a quad guy, not me) that was driving home from a track wasn't paying attention to his task at hand, and veered off the road, hitting some major bumps in the gravel, which in turn caused my bike to launch off the trailer and onto the highway at about 50mph. Cosmetically, not a lot happened to my surprise. Shaved one end of the bars and a footpeg. No scratches on the plastic. It also bent, but didn't break, my ASV clutch lever.

Anyways, once I got home I started it, and boom, the exhaust turned bright red almost immediatly. I shut it down right away. The next day I called some people to get opinions. The most common was gasoline in the oil. So I dropped the oil, added new stuff, checked all my fluids, etc etc. I also changed the coolant. I got my camera out, just in case, and started it up. The following picture is after about 45 seconds of runtime. I was hoping, and still am hoping, it is something simple. Maybe gas in the oil is still the problem?

Anyone have any ideas? It is going into the shop tomorrow.

It is a 2004 YZ450F. WB Carbon Pro Exhaust and PEK performance carb. Just so you have that info.


thats totally normal all bikes do that /w/ no airflow. It occurs more often /w/ ti-pipes. NEVER GET AN OPINION FROM A TECH AT A SHOP!!!!! THEIR IDIOTS /W/ A "TO DREAM OF JOB".

It is normal.

But not every tech at a shop is an idiot. That said, the service write up guys are generally there for their sales ability, rather than their technical expertise, and not every tech at a shop is a master wrench, either.

But if a shop tells you that they can fix that "problem", leave.

It is usuall for some bikes....did it do that before now?

Thats the thing, I don't THINK it has ever done that before. BUT,I have never started it while it is dark outside either. It does idle alot higher than before, and doesn't drop down like it usually does.

choke may have been opened or stuck partly far as my comments about the tech's beying stupid, yes, they are here.....else where...I have no Idea.

Actually, with this particular carb, when the choke is on, it dies out unlike the stock carb when the choke is on.

The bike now has 70 hours on it. I should get the valves checked anyways, so maybe I can use that as an excuse to take it in. Maybe I am paranoid, I have already spent $1200 rebuilding a thumper and I don't want to take any chances.

I know my stock pipe on my 426 would glow red, but I didn't think the WB would. Am I wrong and just never noticed it before?


That is normal.My FMF PB header does it at night when we race supercross.

Kinda off topic but how is that PEK carb and how much did it set you back?

Ok, I understand it is I guess, 'normal', for my pipe to glow, but THAT red THAT fast? Wow, I apparantly just never noticed it.

aedwards07, I got the PEK carb for 250 off of eBay and it is worth every bit of that. They list for 799, and I feel they are even worth that! It is like fuel injection. Check them out!!

Like everyone said before the header will glow and that's normal(and yes that quickly)... BUT I have taken a dinger and bent the pipe slightly, barely noticeable at first glance but a nice crease on the inside bend about an inch in from the head. The header seemed to glow more than usual and pop more too. The only thing I could figure was the restricted exhaust flow caused heat to build up more than usual. I replaced the header and it went back to normal. You may want to inspect both pipes to see if there is anything restricting flow.

People automatically assume that the glowing some people describe is normal, but sometimes its not.

It will glow after a few minutes, but mine will be orange not bright red like that after a few seconds.

I think you may have a big air leak somewhere. Higher idle, red instead of orange, is it popping too?

Check the carb boots.

I had my hot start stick once and got the same thing as you describe. After fixing it I was happy with the faint orange instead of the bright red.

Check it out, something may still be wrong.

45 seconds isn't that fast

Looking at the picture, how dark it is, the fact that it's just a dull red, and an aftermarket header, it looks pretty ordinary to me. :applause:

MARSMELLOWS ANYONE? mine does it also with no air flow....


Time to sell it! :applause:

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