Kawi2strokes.com Forum

Here are two more images of the (rough) measurement of the 72 and 74 cylinders. I've also attached the port map from my 72 shop manual where the dimension from the top of the cylinder to the top of the exhaust port is shown as 36.8mm. I have a feeling that not only was the cylinder shaved, but I bet there was some port work done.

What a mess. Maybe just raising the cylinder back to it's original height with a thicker base gasket and rolling the dice on performance is the way to go.

Dave

The problem here is that we don't know if the top of the exhaust port that you measured was raised from stock. If you measure to the bottom of the port it will probably tell us which surface was cut, since that isn't usually changed during porting. But measuring all the ports is important too, so you know what you have.

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If it surges, that's normal, upshift.

If still interested to find out what you have, measure top deck to bottom of transfer.
Nobody alters the floor of transfers(usually).

66.1 for the H2

cliff

Just a note:
Stock base gasket thickness= 0.5mm
Stock head gasket thickness= 1.0mm

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

Okay, I took some measurements on both cylinders. The 72 cylinder was pretty consistent, measuring about 66.5mm to the bottom of all 4 scavenge ports. A little off from the shop manual but the cylinder has not been cleaned up so there may be a little crud on it.

The 74 is another matter. The ports were even left to right but not front to back. Of the four scavenge ports the intake side ports were a little under 64.5mm to the bottom and the exhaust side where around 63.7mm. Not sure whether this was deliberate but, seeing how consistent it is, whoever did the port work must have done this on purpose. Is there a reason the intake side scavenge ports are different than the exhaust side, even though they are right next to each other? I guess that could affect the way the air/fuel mixture swirls in the chamber.

On a side note all the ports on both cylinders were pretty much the same rectangular shape, not like they are shown on the port measurement picture from the shop manual I posted earlier.

Thanks again for all you feedback. BTW, I did look at the Cometic site and they don't list anything for H models. Bummer. I'd have to stack up a lot of base gaskets to move the cylinder up 2mm.

Thanks again for the responses,

Dave

This is why I recommended measuring those.

.5mm delta off the bottoms of the scavenge ports are of zero consequence, except for top deck measure.

approx 3mm delta on the '74 is indication of skimmed top deck. (.125" or so)

Now cyl. height from bottom deck to top deck and some arith.

cliff

BTW isn't the 74 and 72 scavenge side windows are completely different?

Dale?


cliff

From what I've heard, Cometic will custom cut what you need for a not-too-bad price. I haven't had them make me any though, so I really don't know what they charge.

https://www.cometic.com/custom

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If it surges, that's normal, upshift.

Cliff, I'm pretty sure it a 72 based on the engine number, 1277, and the cutouts on the bottom, which were deeper on the early models and then became less so over the years. I've attached a picture showing the cutout and the scavenge ports. What I don't know is if the cutout is correct. In the picture I've attached you can see the cylinders have a double dip, almost like someone cut out a little more material. Man, I hope I don't have two sets of overworked cylinders. Well, I have to get the 74 going first, so I need to know the correct cylinder height. Anyone have a measurement of a standard 74 cylinder, base gasket surface to head gasket surface? If I can get the cylinders back up to the correct height I think the timing might not be too bad, maybe even a little better than stock.

Thanks,

Dave

The cutouts are not stock, but they won't hurt anything.

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If it surges, that's normal, upshift.

Surely, someone has H2 jug heights here.

Strange nobody has revealed this.
H1 yes, H2 NO.

cliff