two schools of jetting a GS-> checking main's on plu

[The Buddha]

The stock header pipe has the crossover... which is the only pipe I have done any testing with... However the point still remains... with an EGT you are measuring the temperature of the exhaust... too many things, like the thing misfiring due to being over rich, or cross wind etc will affect the temperature. If its covered under the cowling like a race car it wont affect it as much, but otherwise it will, also what is the response speed of the pryometer. Not in the micro-nano second range. A O2 sensor monitors chemical composition, hence its not affected by anything external. The first O2 sensor I have was old, but I have since replaced it with a new one. Its plenty accurate... I have not set it even close to where its borderline. Its well in the rich range. The minimum is ~700 millivolts. It is 500 millivolts for what is called perfect. With carburetion you'll have a real hard time acheiving an exact 500. Max power is made ~ 450 mv, and cars run as lean as 420mv or even 410mv when cruising for maximum economy. With sensor driven carburetion and ignition they do need to have precise adjustments, hence these are very sensitive. On carbureted bikes... you'll have to set it richer than ideal and leave it there. And no it wont do 420 with a 135 main and stock needle either... drop to 145 and it will be near 200 in the upper 1/2 of the throttle opening. Finally its up to the user what he wants to do really.
Cool.
Srinath.

[KevinC]

I only re-jet about twice a month, so the "micro nanoscond" response isn't really an issue. The thermocouple response time might be as long as 1/4 second, but I've never been able to get the new jets in that quick anyway.

"micro nanosecond"? Is that a femto second? Wow, that's fast!

Wind doesn't affect the gas temp in the middle of the pipe 150 mm from the exhaust valve. Check out the racing karts. Everyone of them uses EGT with the pipe hanging out in the breeze. 90% of them are two strokes, and they only sieze 10 times as easy as a four stroke, so I suspect they would worry about getting it right.

[The Buddha]

I only re-jet about twice a month, so the "micro nanoscond" response isn't really an issue. The thermocouple response time might be as long as 1/4 second, but I've never been able to get the new jets in that quick anyway.

"micro nanosecond"? Is that a femto second? Wow, that's fast!

Wind doesn't affect the gas temp in the middle of the pipe 150 mm from the exhaust valve. Check out the racing karts. Everyone of them uses EGT with the pipe hanging out in the breeze. 90% of them are two strokes, and they only sieze 10 times as easy as a four stroke, so I suspect they would worry about getting it right.

You cant be serious KevinC...
I said micro-nano second... Micro is 10 power -6, and nano is 10 power -9, and micro nano would be 10 power -15... or a fermi second I think. I didn't say micro nano... I said micro-nano... The O2 sensor actually specs at a nano second. The digital millivolt meter I have was speced at micro second. I hence said somehting between the 2, between micro and nano...
Thermo couple responses are usually higher.... I have a thermometer fitting in my digital meter... It took over a second to stabilise. But I guess there is different types. However 1/4 second is waaaaaaaaay too much. Your speed at changing jets is not what response time is about... In my eliminator and other bikes that have K&N filters that would be out in the wind on the outer cyl's, the outer cyls would suck air under certain circumstances... and the bike would suddenly go lean for an instant and go back to being rich... you'd barely feel the power loss... and it happens only at high speeds... and will never happen on a dyno in a closed room. It will happen on the road only, and only at pretty high speeds, and on my eliminator... it depends on your leg position... You can cut off the draft, or worsen it with your legs. On air oil GSXR's the draft would kill the things in cross wind. And O2 sensor would pick it up in a flash, and a good 800 will suddenly flash a 200 and back to 800... If the thing took 1/4 second... it will never catch it. Mean while you'll run in circles trying to find the problem.
Now here is another news flash... 2 strokes burn oil... whoo hooo hydrocarbons... hence O2 sensors will show false readings... its a chemical analyser... and pretty soon it will be clogged up with oil... it will simply quit working. By now I am certain... For a gas powered 4 stroke... O2 sensor is it... That the simple reason its there in all cars. Fuel economy might only be one reason.. If pyrometers were better... it would be in all cars and they'd have a small interface that will tell the black box wht is happening. In effect pyrometers are easier to make than O2 sensors... It would have been used instead... They already put it in trucks... so they do mass produce them. Why make more crap... when the crap they make is just as effective... well its not and so the make O2 sensors.
Cool.
Srinath.