Help with a glowing header?

[MXracn746]

I was wondering what would cause a glowing red header. I took the bike apart and checked all the nuts and bolts, and cleaned the carb and put the thing back together and now the header pipe glows red hot within a minute at idle. Any ideas what I might look for?

 

[C Hudak]

First thing I would check would be the hot start cable and plunger, make sure you hear the plunger snap back closed. One way to check A lean situation or a problem with the hot start is to pull the hot start in while its running. If there is no change in the RPM of the bike you have a lean situation somewhere. I have had some stock titanium headers glow red in the dark, maybe you just never noticed.

 

[MXracn746]

It's an 04 YZ450F. I'll start there. It does seem a little slugish when I pull it.

 

[John250]

I thought you got rid of that bike when you got the Suzuki.

 

[TwentyThreeMX]

first 4 stroke i got i freaked out, then realized you just cnat let them sit and idle like that. especially noticeable at night!

 

[LuckyStar64]

Could be running lean. You could try and run some coolant additive that claims to run cooler than just regular antifreeze. I think that's pretty normal for a 4 stroke though. --L*64

 

[hershey]

Its a 4 stroke, they all do it at idle you just dont see it in the bright day light. If you are in fact seeing it in bright lighting situations then it is running too lean at idle.

 

[MXracn746]

I did. Then I sold the RMZ and got this one. We had some things we had to take care of this year so... here I am. I've had a torn PCL since March and just now trying to exercise and ride. I'll take a look at the carb. again today. Thanks guys!

 

[MXracn746]

Well, the hot start works as it's supposed to, and I cleaned out the carb again and all the jets are stock with the needle in the stock position, 4th slot down and the fuel screw at 2 turns out. But I did notice the intake valve clearances a little too tight. The left one is good, the middle one is just about .010 too tight and the right one is about .030 too tight. Supposed to be from .100~.150mm. Weird, but that's how I see it. Exhaust valve clearances are good. What do you guys think. I'm gonna try to find some pucks tomorrow

 

[GeorgiePorgie]

Don't let it idle. Don't rev the piss out if it in the line either.

 

[flyin polack]

Pilot too lean, don't let it idle too long.

 

[MXracn746]

Two out of three of the intake valve clearances were too close. The camshaft journals worn a bit combined with improper shims under the lifter buckets causing a lean condition as only one intake valve was correct. At least that's how it looks to me.