Compression

[MattKDXhager]

Im new too the kdx. Is it normle for a 97 kdx 200 to feel like it's easier than normle to kick over? Almost like low compression.
Bike runs great super peppy doesn't seem to be tired but I'm curious.

[SS109]

KDX's can run pretty well even with low compression. Have you done a compression test?

[kdxsully]

I think my manual said 120 is the low side.

[SS109]

My manual says compression range is 95 to 151 psi. That is super low!

[G22inSC]

As SS109 stated, the Factory Manual does list the useable range as 95 - 115psi. I've often wondered how they come up with this number. I also always see people state "my fresh top end measured such and such psi." There is always the difference between compression testers, cylinder hot or cold, throttle open or closed, each person's individual technique, etc. I'm curious if we could mathematically figure what our compression should be.

For instance, lets say my current local air pressure is 14.48psi (pressure at sea level is 14.92psi). We know the listed KDX compression ratio is 7.9:1.

Should that give us a tested compression of 14.48 * 7.9 equalling 114psi?

Is there a correlation such as this or is this complete non-sense?

[doakley]

Nice concept for a theoretical discussion, but, I think your earlier statement overrides any discussion results. The variations between testers, equipment, technique, etc I believe make a specific number meaningless. I think it is much more meaningful to keep a running record of compressions all done in the same manner. I do mine with an ambient temperature engine, throttle wide open, rapid kicks until the needle no longer raises. I do this periodically and write the results in a notebook along with the date. This way I can see any trends developing.

Just a FWIW.

[KDXGarage]

getting a baseline is helpful

[bufftester]

Is it feeling easier than previously, or easier compared to a different bike? KDXs are pretty known for ease of starting.

[Brian]

You'll be fine. Just ride...