Stochiometric refers to the mixture of air to fuel that will result in complete consumption of the air/fuel mix. That is, all of the fuel is used and all of the oxygen in the air is used during combustion. Most authoritative sources list it as 15 to 1, but I have seen it incorrectly stated as 14.7 to 1, which is what you might have seen.
Stochiometry has nothing to do with engine compression pressures. It is all about combustion of the air/fuel mix.
The standard atmospheric pressure is 14.7 psi. It is the standard atmospheric pressure that is multiplied by the effects of compression to get to the results that are seen on a pressure gauge. In your case, 5.9 (for cylinders 1 ~ 4) multiplied by 14.7 equals a mathematical pressure of 86.73. So you say to yourself, why don't I see that on my gauge.
With the compression of air, its temperature will rise. A rise in temperature has an effect on the pressure of the air. The higher the temperature the higher the pressure. It is a compounding effect if you will.
Many other variables enter into the equation. Gauges are misleading, the speed the motor is being cranked will effect the compression pressure seen and the atmospheric pressure is constantly changing all of the time. Could you or I or anyone see the difference on a compression gauge between two perfectly good cylinders with one being at 5.9 to 1 and the other being 5.7 to 1? I couldn't.
There is nothing absolute about compression values seen on a gauge. They are just general indications (one of many) of the health of a motor.
Don't be hard on the Yam boys. There is too much to know about all of the various Yamaha models that it can become mind boggling. One guy there cannot know it all.
Stochiometry has nothing to do with engine compression pressures. It is all about combustion of the air/fuel mix.
The standard atmospheric pressure is 14.7 psi. It is the standard atmospheric pressure that is multiplied by the effects of compression to get to the results that are seen on a pressure gauge. In your case, 5.9 (for cylinders 1 ~ 4) multiplied by 14.7 equals a mathematical pressure of 86.73. So you say to yourself, why don't I see that on my gauge.
With the compression of air, its temperature will rise. A rise in temperature has an effect on the pressure of the air. The higher the temperature the higher the pressure. It is a compounding effect if you will.
Many other variables enter into the equation. Gauges are misleading, the speed the motor is being cranked will effect the compression pressure seen and the atmospheric pressure is constantly changing all of the time. Could you or I or anyone see the difference on a compression gauge between two perfectly good cylinders with one being at 5.9 to 1 and the other being 5.7 to 1? I couldn't.
There is nothing absolute about compression values seen on a gauge. They are just general indications (one of many) of the health of a motor.
Don't be hard on the Yam boys. There is too much to know about all of the various Yamaha models that it can become mind boggling. One guy there cannot know it all.
