Port timing

[RoostiusMaximus]

Is there a Connecting rod length difference in any years of these engines?

[kwakman]

no.same bore stroke and rod length.

[RoostiusMaximus]

i'm guessing no one is worrying about changing port timings when using the 1mm shorter CR rod in these engines?

[Motorrad]

i'm guessing no one is worrying about changing port timings when using the 1mm shorter CR rod in these engines?

Every time I have seen a cr rod used.. Was to counteract a stroker crank.

[RoostiusMaximus]

Hmmm, I'd read in a PDF

"The typical modification in the early 90's was to use a honda cr 500 connecting rod as it was larger and did not break as easy as the standard kx 500 rod"

[DoldGuy]

http://www.kxriders.com/forums/index.php/topic,6716.0.html

[RoostiusMaximus]

I'd read that, dudes make no sense. 1mm is .040" so having the piston .040" further down the hole is not going to make it run off the exhaust port, the piston will be further on the port. I haven't measured the length of the KX piston yet. I'd better hold out until i yank these motors apart tommorrow night and see whats up. i have both versions of the CR500 rod in stock so we'll see how it goes.

[DoldGuy]

CR500 piston has 2.5mm (or .100") positive compression height versus the KX500, so if you run the CR Rod (-1mm / .040") you still have a positive height of 1.5mm (.060") which leads to the base plate like Don46 has mentioned.
DoldGuy

[RoostiusMaximus]

ah, I was expecting to bore the pin bore on the kx piston.