Whats the difference between the two ? And why do they do pulls in both gears ?

 

One of the most common differences when conducting roll-on power tests on a dyno is in the gear used during the test. Although fourth gear has been the “de facto standard”, some dyno operators prefer to use fifth gear, and now 6th gear, which can distort comparisons. Power readings recorded in fifth or sixth gear are generally higher than those performed in fourth gear. Also, a final drive ratio such as 3.15:1 will often show a higher power reading than a 3.37:1 ratio. Generally, the higher the transmission gear, the greater the engine loading and higher the power reading will be. Since the higher gear ratio slows the engine’s acceleration rate, less power is required to accelerate the rotating and reciprocating parts.

 

My bike is a 5 speed. So if I'm reading you correctly, my numbers would be higher than posted in my sig if the run was done in 5th gear ?

 

Short answer is yes but all conditions would have to be equal, i.e., same dyno, room and ambient temp, tire size and pressure, clutch hooking up, correction factor, etc. You could do another 4th gear pull and your numbers would likely be different; could be higer or lower.

4th gear has been the standard in the past so when comparing dyno data, the comparison is apples to apples.

 

You forgot planetary alignment