The stock headers are stainless thats why they turn red so easily.

An exhaust will glow brighter with a slightly rich idle mixture. If the mixture is too rich it can not be completely burned in the combustion chamber, the fuel goes out into the exhaust pipe and finishes burning causing the pipe to glow. Would Bombardier send out a bike dangerously jetted? The slightly rich idle condition gives better throttle responce when you hit the gas this is why they do it.

Low timing will also cause the same condition. The mixture is lit too late and can not completely burn durning the combustion cycle it goes out into the exhaust and the pipes are glowing again.

A very rich engine will stop the exhaust from glowing if enough fuel is coming through to quench the heat.

There is a hot side of lean and a cold side. The hot side is when you are getting enough fuel to keep the explosion hot. When fuel is cut back to the cold side of lean there is not enough energy to create heat after all fuel is what causes heat not air.

Has anyone every really seen a naturally aspirated 4-stroke melt down a piston from being too lean??

 

eric - i understand they wouldn't send out a bike close to lean, but since the exhaust and intake flow more than stock jetting needs to be changed correct? hes running a 180 or 185 dj main and the 45 pilot, can't remember exactly wat the needles set at, i think 4th groove, and we're around 600feet, he pulled the outside plug out the other day and the threads on the bottom of the plug were kinda black, but hes always running quite a bit hotter than mine(although i have a supercooler,but he has water wetter), which make me think hes lean, but by wat your saying it almost sounds like hes rich, which makes me [img]i/expressions/face-icon-small-confused.gif[/img], and jetting is obviously not my strong suit

 

Im w/ Eric on this one. Ive mentioned this in the past but most leaned toward the idea of being lean. also as a side note I instaled a air/fuel meter and O2 sensor my first run out was at 155 main I thought ran really great. well by time was done I ended up at 145 main the bilke felt like it ran better, I was running rich. my mid was running rich so I went from a 96 needle to the 97 and the mid is still a bit rich. so all in all the meter is telling me that my jetting was off at my best judgement. just food for thought. I will keep you posted on my jetting findings since are bikes are close to the same set up and we live close.

 

When you say 4th groove, is that from the top down?
Dynojet for stage 3 is 3rd groove from the top.
If you are in the 4th from top, you could be alittle rich.
You have two choices:
1- Lower the needle to 3rd from top.
2- Check the length of your slide spring.
If longer than 3 1/8, cut to a final length of 3 to 3 1/8 inches.
This will give you more air at bottom/mid and lean out the carb alittle.

 

Are you sure the intake and exhaust changes require richer jetting? Everyone thinks an exhaust change needs more fuel but we have found a different story. I have made changes to an engine and gone down as far as a#145 main. Sometimes the increased velocity through the carb causes more vacuum and pulls too much fuel in which requires leaner jetting.

 

The dynojet needle has a very simular start and end sizes as the stock needle.
The main issue here is that just has you start to accelerate the DJ needle is .011"
smaller than stock, this with the aggressive RW cdi causing more vacuum and thus more bottom end velocity, results in a very rich condition at bottom/mid range.
Weakening the spring will not only add alittle air, but reduce the velocity at this point.
You may have to do both, check the spring and lower the needle, if not in the 3rd from top groove. Then has Eric says, change the main to reflect what the motor wants.
We can only assist, but we are not there and your motor is telling you what it needs.

 

Move the needle up one notch, change the main jet, cut the spring, run lower octane, run higher octane, change header pipe, run a uni filter, check spark plug color, are you running too lean, are you running too rich, is the pilot jet the correct size, aggressive CDI or mild CDI, move the needle down three notches........................and so on and so on....


Sounds like allot of experimentation and trial and error to me. Know wonder people keep asking the same question. There's got to be a method of setting the correct AFR that is more definite and consistent......... [img]i/expressions/face-icon-small-disgusted.gif[/img]

 

here is a pict of his plug and my plug, didn't turn out that well, but in the top part you can see where mine is darker, which seems like his is lean, but I will probably play with the needle settings, and if dropping the needle helps but doesn't 100% cure it i'll cut the spring some as well, i'll report back tomorrow and let you know what happens,

Sam- are those figures for the TM or stocker?

 

Web Site Blocked by the 3Com SuperStack 3 Firewall..........Grrrrrrrr I hate that.... [img]i/expressions/face-icon-small-mad.gif[/img]

 

Is that MBRP a slip on or full pipe. If its a slip on junk the DJ kit put the stock needle back in at the 4th position and put a #160 mikuni main in it.