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"The H seems more responsive and snappy in the upper RPM range, while the E bike has a smooth and harder pull from the bottom. That would indicate the opposite of what these numbers are showing, yes? "

That sounds right to me. Higher compression is more advantageous for mid range power.

All else being equal, the higher compression in the H model engine should give it stronger pull from low range up to 6k RPM (when the kips activates). In my experience, it does not. The E engine will walk all over the H until getting into the very top end of the RPM range. That's just personal experience of mine from riding both. YMMV.

Great collection of bikes !!
200 PSI ,,,, WOW ,, Thats an awesome top end for a KDX.

Julien D wrote:All else being equal, the higher compression in the H model engine should give it stronger pull from low range up to 6k RPM (when the kips activates). In my experience, it does not. The E engine will walk all over the H until getting into the very top end of the RPM range. That's just personal experience of mine from riding both. YMMV.

The E model has the higher compression .

And I believe it would pull so much better than an H below 6000 rpms.

Has anybody ever measured how they got the extra compression ?
Is the head that much different ? Cylinder shorter ? Thats quite a difference in numbers.

C George wrote:

Julien D wrote:All else being equal, the higher compression in the H model engine should give it stronger pull from low range up to 6k RPM (when the kips activates). In my experience, it does not. The E engine will walk all over the H until getting into the very top end of the RPM range. That's just personal experience of mine from riding both. YMMV.

The E model has the higher compression .

And I believe it would pull so much better than an H below 6000 rpms.

The E model has a higher "usable range" as stated in the manual, however, it has a lower compression ratio. At least for the "low speed" rating. This is obviously conflicting information.

I may be wrong but I believe the compression psi number higher on the E is what you feel.

Compression ratio's are confusing and very hard to really measure on a two stroke.

What they'll push for pressure out the plug hole seems to be key.

But ,,, I've been wrong before.

No, I agree with you. In my experience the E will test at a higher PSI, and that would explain the gain in low end power. After a replate/rebuild my E was at about 170 PSI. I just question the published numbers as far as compression ratios.

I'm in the middle of a new 220 top end for my son's 200 and am sending the head off to RB.

To get 190 -200 psi of compression , I asked for a "race gas " head.

But as I've commented before , I have no problem blending in AV Gas to have a TRUE 95 octane fuel.

A conventional 220 head reworked should make 170-175 psi.