Res vs. On

[sprtrx300ex]

My 400 seems to have more power when the fuel valve is in the RES position. Does this mean my jetting is a little lean when I run it on ON?

I read somewhere that more fuel gets to your carb in the RES position, making you run richer.

My tank is full also.


Any Ideas?

[UglyMotha™]

wow :huh


well um, your bike runs the same whether or not your on "on" or "res", you carb recieves the same amout of fuel res stands for reserve and it is there just to alarm you that your just bout out of gas and you better head home

kinda like your cruising alon with the valve in the on posistion, you run outta gas, put it on res fire it back up head home and refuel :o

[ballisticpb]

your petcock could be dirty causing the flow in the "ON" position to not feed enough fuel into the carb. but i have never heard one position giving you more power than the other.

[sprtrx300ex]

im almost 100% sure its clean, but Ill check. Doesn't reserve some how bypasss the filter screen?

Im kinda confused, becuase no matter how much fuel gets into the carb at whatever speed, You jetting regulates what gets to the engine , correct?

[44oEX]

yes and the fuel can only go in the carb untill it's full then the flots close the carb. you could use a 2" line to feed the carb if you want ones is full it's full.:huh

[UglyMotha™]

Originally posted by sprtrx300ex
im almost 100% sure its clean, but Ill check. Doesn't reserve some how bypasss the filter screen?

Im kinda confused, becuase no matter how much fuel gets into the carb at whatever speed, You jetting regulates what gets to the engine , correct?



its all in your head :o

[UglyMotha™]

Originally posted by 44oEX
yes and the fuel can only go in the carb untill it's full then the flots close the carb. you could use a 2" line to feed the carb if you want ones is full it's full.:huh



its a float :o and whats the point of running a larger line when you just have to choke it back down at the nipple, your not goin t passs any more fuel and it doesn't matter how much fuel you feed the carb its only goin to allow as much fuel as your jetting limits

[sprtrx300ex]

I deffinitly noticed an increase in power, especially top end. However, it was also about 15 degrees warmer. Maybe that had something to do with it :confused:

[sprtrx300ex]

Originally posted by UglyMotha™
its a float :o and whats the point of running a larger line when you just have to choke it back down at the nipple, your not goin t passs any more fuel and it doesn't matter how much fuel you feed the carb its only goin to allow as much fuel as your jetting limits

I think he was just saying "it doesnt matter what size line you use, your carb can only hold a certain amount"

[44oEX]

Originally posted by sprtrx300ex
I think he was just saying "it doesnt matter what size line you use, your carb can only hold a certain amount"


yeah thats it. thanks at least some take the trouble of reading and understanding.

[wilkin250r]

The ONLY way I can see that being possible is if your petcock is clogged, or you you have some contamination in your fuel.

[GUTSIE]

only thing i can think of is ur petcock is dirty at the top and when u put it on reserve it sucks from the bottom (RIGHT?) so that may be ur problem check it out to make sure