KZ810 or GPZ 810 specs or dyno results...

turboguzzi wrote: Here in Italy, finding 98 octane at a station is quite easy, so living with a 10.5:1 or even 11:1 air cooled street motor is doable. If what you can get at the pump is only 92, then these numbers will be lower.

Wow, that's incredible. Around my parts, 91 is typically the "premium" fuel and has a 10-20% addition of ethanol, which I believe is in itself an octane booster. Very few stations offer non-ethanol and even fewer offer "race" fuel with 98~ish octane.

The general consensus on this is that 10.25:1 or 10.5:1 is about the max most guys will run on the street with these bikes. But fuel quality, temperature, and other environmental effects will affect how doable this is, but again - there are guys in Cali, Arizona, and Texas running 10.25:1 piston kits without an issue. Depending on the temps where you are you may want an oil cooler (with thermostat) to help with cooling as increased compression also generates a bit more heat.

DoubleDub wrote: Yes, mostly because of the limited ability to cool. Overheating an air cooled motor *can* be easier to do than a water cooled engine that has a near-constant flow (or regulated by thermostat) of coolant removing heat from the engine combustion area.

This and combustion chamber design, electronic fuel injection, and other improvements are what allow modern bikes to run 11:1 and higher compression ratios without danger of detonation.

Think more like 12.5:1 - 13:1 at the sharp end of sportbikes BMW 1000, zx10, etc.

More pressure like 11.1 is meaning less if the limit of trapped volume has been exceeded.

This will happen at a certain rpm and throttle opening. When you hit the wall you need to know is it cam timing limiting the power range is head limiting flow through the in and out system.

The higher compression will accelerate the mixture and move more volume as well.

If the head is flowd out (volume of air in maxed, air out maxed) You have to open the exhaust ports and trim the valve to get more real world volume that condenses into hp in the way it allows more intake velocity and volume to enter. :evil: Pretty soon if you hold the intake open longer and spin it faster it stuffs the cylinder like a gaint fist, ramming in air like turbo effect.

The best part it don't quit. Not anyomore. 7 to 10 is a broad spectrum of power with almost unreal torque and hp, totally controllable. At 4 it starts pulling good and and saunters through the 5 and 6 somewhat mushy (the 28's play hookie with me in this range),

shell go 7 to eleven, 8 to 11, 9 to eleven or 9.5 11.5 real fast with tons of torque.

It's the head.

Now it needs 34's with larger diameter insides then i'll be in the nine sec range.

Went from lifting the front wheel off the ground at 6grand stock to capable of an 80mph wheelie.

So don't worry about the pressure ratio, just stay around 180psi for a stock head.

That's already past the heads flow capacity stock.

Cam timing down to 104 is potential trouble, the pressures are getting too high.

but you can run them by backing your timing down some, and then your stuck with whatever power you have.

Be careful guys. European fuel and US fuel are completely different. Here in the US most gas is Octane boosted with Ethanol. In Europe the Octane is boosted with Xylene. The two fuels burn quite a bit differently. This is why European fuels have more octane besides the fact that European octane ratings are not figured the same way as US Octane ratings. I regularly add Naphthalene and Xylene to my fuel to offset the shitty Ethanol that we add to our gas here in the US. On hot summer days you can really tell the difference. The Naphthalene counteracts the Ethanol and the Xylene stabilizes the Octane #s. Naphthalene by itself has a Octane rating of only 90, but has a very hi energy density because it goes from a solid to a vapor without the transitional liquid. Xylene on the other hand has an Octane rating of 117 and Ethanol is 109. The other problem with Ethanol in the fuel is that it makes it Hygroscopic, therefore it promotes corrosion. Also the burn ratio of xylene is a bit higher than gasoline so the fuel efficiency actually goes up. Unlike Ethanol where the burn ratio is about 7:1 which drastically reduces fuel efficiency. In other words, European Gas is MUCH better than US gas in every way.

In other words, European Gas is MUCH better than US gas in every way.

Why they don't use the same formula ?

Maybe it's why the gas in Europe is damn expensive compared to US. ??


best regards,
laurent

ELCouz wrote:

In other words, European Gas is MUCH better than US gas in every way.

Why they don't use the same formula ?

Maybe it's why the gas in Europe is damn expensive compared to US. ??


best regards,
laurent

The main reason is because of the large US Ethanol market. The US produces a large amount of corn and out of that comes Ethanol. This is the same reason why the additive of choice is not Butanol which is a much better Alcohol for fuel use than any other Alcohol. Butanol is produced out of Chlorophyll based plants such as grass clippings, leaves and other green plants and has a Octane rating of 90. These just are not a economical produce. Butanol could be the answer to all of our fuel problems for internal combustion engines. I used to run it in my stock KZ900 all the time a few years ago when I had regular access to it. The use of Butanol required ZERO engine or carb modifications including jetting. Butanol also has a combustion ratio of about 16:1

otakar wrote:

ELCouz wrote:

In other words, European Gas is MUCH better than US gas in every way.

Why they don't use the same formula ?

Maybe it's why the gas in Europe is damn expensive compared to US. ??


best regards,
laurent

The main reason is because of the large US Ethanol market. The US produces a large amount of corn and out of that comes Ethanol. This is the same reason why the additive of choice is not Butanol which is a much better Alcohol for fuel use than any other Alcohol. Butanol is produced out of Chlorophyll based plants such as grass clippings, leaves and other green plants and has a Octane rating of 90. These just are not a economical produce. Butanol could be the answer to all of our fuel problems for internal combustion engines. I used to run it in my stock KZ900 all the time a few years ago when I had regular access to it. The use of Butanol required ZERO engine or carb modifications including jetting. Butanol also has a combustion ratio of about 16:1

where do you get butanol?

Regarding Xylene.... i think toluene is in the same category. At least i know where to get it and it's around 5$ gallon.

But i don't know if its compatible with our engine/carbs (corrosion or degradation of parts)

regards,
laurent

Yes that is correct Toluene will work also. It has an Octane rating of 112 and is in the same family as Xylene. I buy both at Sherwin Williams.

No, head work on a 1970's KZ gains 15mph over the same bike with a stock head.

You are not comparing apples to apples here.

We've gotten way off the original topic here, anyway.

Hi Folks,

I moved luten's offer to sell a head to the classifieds, where it should have been posted in the first place. The rest of the missing posts are quarantined in the mods forum for now.

Bill