Maintenance & Technical > KX500 Original
Exhaust valve timing..?
John:
More to think about?
If the spring is pre-loaded it will take more power to compress it hence a higher RPM to open the exhaust valves. How will this affect the engine characteristics though? Will the power band be leaner or more aggressive?
Changing the spring to a weaker one will make the exhaust vales open earlier. How would that change the engine characteristics?
I am lost with two strokes; and a lot of beer doesn?t help?
Interesting thread though and a wonderful forum!
//John
GDubb:
All this talk is reminding me of the centrifical (?) clutch on my gas powered R/C truck. You lighten the three clutch shoes so that the weight of the shoes doesnt carry them out to make contact with the clutch bell untill they are spun at a higher RPM... therefore the engine is making more power before it is sent through the drivetrain to the wheels. I think a heavier spring would slow the whole process evenly(higher rpm to open, but open at the same rate of speed) while lighter balls or steeper ramps? would cause the exhaust valve to hesitate opening until higher rpm is reached but sort of slamming the exhaust valve open creating more of a "hit" with the power band.
I could be totally wrong and far off base... just a little brainstorm I had when I realized this was all sounding like the clutch on my R/C truck. I really dont have any real life experience or knowledge with KIPS valves so hopefully this is of some assistance and not just a waste of space on the thread. :wink:
YUNGGUNNAZ:
never a waste.there is always something in thought that can be put to use.i would say you're probably on track with heavier spring bringing on harder hit.boy what a ride that would be! now how would it act thru the bottom range?what if we changed the number of teeth on plastic gear to spin it at a quicker rate.if we could find one.does a kx125 or 250 have same number of teeth.these should spin at faster rate or open quicker.man,now i've got to pull my cover off my 250 and 125.
mun:
Mayby 2 dyno picture more explain better than i able write english.
YUNGGUNNAZ:
does it apprear that valve begins to open at around 4300-4400 and maybe climbs on pipe around 5300 are so.what would you say the reason for decrease in power with valve open constant?timing of power curve vs. type of pipe involve or not burning of as much fuel charge cleanly.where did the other 2. hp go from previous graph?interesting.there is a performance gain here somewhere in tuning of this valve with other mods. include in the equation.
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