Kawi2strokes.com Forum

Thanks. I get it now, makes perfect sense. So the proper way is to get to zero deck height then do all the measurements or know where the top of the edge of the piston is and measure from that point.

You got it. If you're not going to try to get the heads to what's considered proper squish, then you can leave the decks alone. You just have to know the distance from the piston edge to the stock deck so you can add that to any top-down measurements in the specs. Also, you need to know if the specs had that added already, as was being discussed above. I think the Denco port specs are measured from the top of the stroke, not the deck, but I don't have enough information to be able to argue that point.

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If it surges, that's normal, upshift.

Gerrit, the Denco stuff has to be taken with a BIG handful of salt. After talking a bunch with Tony for years Most all the hp figures were made up, and the true ones were done on a crap dyno with a whipping chain. Their 149 hp porting is actually their 133 hp motor, it ran 149 mph, so Dennis fudged it. There were secret mods and a bunch of other stuff that Dennis just made up.

Specifically asked Tony about the deck height and porting, he told me it was zero deck. So that's how I see it. The specs are actually 40 years old, and there are more modern specs out there........

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Twist the throttle, tilt the horizon, and have a great time. What triples are all about...........

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Answers are here: http://kawatriple.com/

JA, I don't doubt for one second that there are far more modern specs out there. Re zeroing the cylinders, that would remove at least 1 mm from the gasket surface and if the Denco specs in the sheet were based on zeroed cylinders then the exhaust and transfer mods become minimal in several cases, almost not worth the bother.
As an example, the exhaust port for the 70 HP H1, listed as 33.8 mm from head gasket surface, or 1.6 mm increase in port height compared to stock based on stock cylinder. Remove the 1 mm or so from the gasket surface and apply the same 33.8 mm. You then get an increase of only 0.6 mm in exhaust port height. Is this worth the effort?
While the zeroing of the deck height may be necessary, the sheet doesn't actually say so anywhere- nor does any other Denco documentation I have seen, though I freely admit that I don't claim to have everything Denco ever released on paper.
Another thing the sheet does not mention is transfer angles- are they altered in any way compared to stock? Carb sizes aren't mentioned either, nor compression ratios, which spannies to use, etc. All in all the spec sheet raises more questions than it answers.

If you look at http://kawatriple.com/portdencoh1.htm the ports are specified in crank angles rather than a specific mm. This particular example equates to the 70HP in John's chart.
When you calculate piston position from the crank angle (zero deck) there is a difference of approx 1.6mm compared to chart dims. That would tend to make me strongly believe that chart dims are derived from cylinder head surface rather than piston TDC.

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Answers are here: http://kawatriple.com/

Gee, I didn't mean to start a pissing contest. John, maybe when Tony says "Zero Deck" he means that the deck (not piston @TDC) is the zero (reference) for the measurements?

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We don't need no stinkin' Cams!

No pissing contest... just a legitimate question deserving an answer that there is a difference of opinion on. It gets the wheels turning and maybe something is learned in the process which is a good thing.

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Answers are here: http://kawatriple.com/

Thanks for the confirmation of my observations/posts on page one Dale.

I subsequently measured the difference from the head gasket surface to the piston crown's perimeter edge at TDC ,of a stock 500. The measurement was 1.36mm. If you factor this into the equation to arrive at zero deck height the Denco 70 spec moves the exhaust port up .24mm (.009in). This is nothing.

However using the head gasket surface as the base line results in an Ex port lift of 1.6mm, as I posted on page 1.

J

My 2 cents, put the barrels on the cases w/ pistons, mount a degree wheel and measure the duration in degrees of rotation that the ports are open. Just like degreeing a cam in a 4 stroke. Then go read A Graham Bells books for recommendations on port timing. Measuring from the top of the barrel is just a way of copying already ported barrels. After porting the squish clearance and compression ratio is set by adjusting deck clearance and chamber volume.

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Don