| Author | Message | ||
     Acab |
Anyone run regular in their XB instead of premium? Besides compression ratios why do certain motors call for higher octane gas? | ||
| Old_man |
XBs are not designed to run on regular. I would not use it to save the few cents a gallon, and risk detonation. | ||
| Acab |
I guess I am just wondering why some engines need premium. | ||
| Old_man |
Regular gas burns quicker and easier than premium. It can explode instead of burning in an even front in the cylinder if the compression is too high for it. This explosion is the knocking sound that is heard when it occurs before the piston has reached the top of its travel in the cylinder. This can cause damage. | ||
| Honu |
Air cooled motor tends to/or can run hotter and with compression can cause pre-mature detonation??? I am guessing here. | ||
| Lovematt |
When a spark ignites the fuel mix, although an "explosion" occurs...the fuel should actually burn in a wavefront fashion across the combustion chamber in a controlled fashion to make the motor run right. This is dependent upon a number of factors such as compression ratio, temperature of the motor, the materials used for the parts, the octane of the fuel (which controls how fast it burns or "explodes"), timing of the valves/spark, etc. If the motor is designed assuming the fuel was at a certain octane and a lower octane is put in, the motor is now potentially at risk because the fuel will burn/explode too fast and may even burn too soon. This screws up the mix of variables mentioned above and could cause damage. It is effectively the same thing as starting the spark 30-80 degrees sooner than it should be in a random fashion...not good. That being said, the fuel is only one part of many variables as noted above. Once built there are only a few things that can be adjusted without doing a rebuild (fuel octane, fuel delivery via carb/injectors, spark timing, fuel delivery, etc). When a car or bike has a recommended of a given octane, it is fine to run a HIGHER octane than that although it may not be necessary. However it is not a good idea to run a lower octane. I have heard some people state that if the weather is cold then the octane can be dropped...however the motor is still at operating temperature and the heat inside the combustion chamber is way higher than that....the fuel still generally sees the same conditions no matter what the outside temperature is. The air vs oil vs liquid cooled does have a factor but the method of cooling is simply another variable added to the mix noted above... (Message edited by lovematt on May 21, 2006) | ||
| Rhun |
to go to the other extreme has anyone ran leaded fuel in a Buell? My drag racing friend got miss shipped a five gallon can of 116 octane leaded. With the price of gas and this being free, it is tempting. I'm not expecting an appreciable power increase. PS: 04 XB12R not California, therefore no O2 sensor, I believe. (Message edited by rhun on May 22, 2006) | ||
| Jkhawaii |
all XB's have O2 sensors. there is 100+ oct unleaded avalible | ||
| Perry |
Don't use leaded gas - it will hose your O2 sensor very quickly. The O2 sensor is not an emissions thing - it measures the Air/Fuel ratio (by measuring residual oxygen) and then adjusts the fuel injection accordingly. So, it is basic control of the Fuel Injection and present in all XB bikes. |
