- Joined
- Feb 6, 2006
- Messages
- 11,918
- Reaction score
- 5,400
- Location
- Cape Town, deep in the lentils
- Bike
- KTM 990 Adventure
All anecdotal but I am curious...
I bought a set of FCR pumper carbs in the past that were jetted for a 950 in the US. It ran stupid rich. Not just a few main jet sizes too big, the needle needed to be leaner.
I have noticed that stock and aftermarket maps designed for 990's run quite rich here. The Akro maps in particular. (The newer KTM models have much more sophisticated and sensitive fuel systems and thus, I presume, can modulate and compensate to run more efficiently.)
For the older more analogue systems and carbs, I have a suspicion that they run richer, because our fuel doesn't have any ethanol in it. It is therefore slightly more energy dense than European and in particular US fuels and thus need more air.
I am curious, I know that ethanol mix reduces the energy in fuel by about 2% thus fuelling needs to be slightly richer to compensate, but does anyone have more info or know a thing or two about our fuels as compared to European and American ones?
I bought a set of FCR pumper carbs in the past that were jetted for a 950 in the US. It ran stupid rich. Not just a few main jet sizes too big, the needle needed to be leaner.
I have noticed that stock and aftermarket maps designed for 990's run quite rich here. The Akro maps in particular. (The newer KTM models have much more sophisticated and sensitive fuel systems and thus, I presume, can modulate and compensate to run more efficiently.)
For the older more analogue systems and carbs, I have a suspicion that they run richer, because our fuel doesn't have any ethanol in it. It is therefore slightly more energy dense than European and in particular US fuels and thus need more air.
I am curious, I know that ethanol mix reduces the energy in fuel by about 2% thus fuelling needs to be slightly richer to compensate, but does anyone have more info or know a thing or two about our fuels as compared to European and American ones?
