Power Commander V

[Turk]

Thanks Mark. 10$/gallon I'll stick to original settings then.

 

[switchback]

In my experience a bike that is tuned to run correctly does not necessarily get worse fuel economy. The PCV takes input from the O2 sensor to calculate optimal fuel mixture. Older Power commanders were more of a guessing or dyno game and often bikes would be set up richer than needed.

 

[markjenn]

In my experience a bike that is tuned to run correctly does not necessarily get worse fuel economy. The PCV takes input from the O2 sensor to calculate optimal fuel mixture. Older Power commanders were more of a guessing or dyno game and often bikes would be set up richer than needed.

The words "correct" and "optimal" require qualification. Correct/optimal for what? Fuel economy, power, throttle response, emissions? Mixture is a tradeoff - an engine that is tuned optimally for one is not going to be optimal for the other.

The main reason PC's are fitted is to optimize for a different criteria that stock, not to "correct" for something Yamaha did wrong. What governs most stock mixture maps is getting the lowest emissions at moderate power settings where the bike tends to run the most during the emissions test cycle. This is the reason stock mixtures can exhibit "lean stumbles" or "light surging" in the mid-range at light throttle and low power. Released from the need to meet an emissions test, a PC-ed bike can do better in this area. A little richening of the mixture in the mid-range can make the bike run a lot better, but it will typically increase fuel consumption. How much depends on the fuel map used or how much fuel bias is introduced by the PC. It may be a pretty small penalty or it may be huge, depends on the setup. But it is uncommon for fuel consumption not to increase at least a little and emissions are almost always higher, sometimes ridiculously so.

Since the introduction of modern closed-loop FI systems and cats, most modern stock FI'ed bikes run pretty darn well stock with some exceptions. My suggestion for someone considering a PC is to ride their bikes for a while stock and see how they perform, especially after they make any mods to intake or exhaust. Let the bike tell you what it needs, not internet forums.

- Mark

 

[switchback]

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[Koinz]

Since the introduction of modern closed-loop FI systems and cats, most modern stock FI'ed bikes run pretty darn well stock with some exceptions. My suggestion for someone considering a PC is to ride their bikes for a while stock and see how they perform, especially after they make any mods to intake or exhaust. Let the bike tell you what it needs, not internet forums.

Just to add. Closed loop is not achieved until the O2 sensor reaches operating temperature. Thats why some have heaters to get them into closed lop sooner. When cold, the air temperature sensor manages fuel enrichment. Also, O2 sensors get lazy with age or get carboned up providing incorrect signals to the computer causing driveabilty issues or too rich a mixture.

Nice write up Markjenn.

 

[spasm]

interesting thread this, i can tell u all this. i done 2000 miles on mine standard, and have done the same with the pcv fitted with a full system on. completely different animal, no question this bike pulls much harder right up through the revs in every gear, and fuel consumption is about the same as the guys that tuned it actually took fuel out when mapping. i suspect the fuel economy is better but on the other hand you tend to right the bike harder because you can lol thus guzzling more fuel ::022::

 

[Tremor38]

interesting thread this, i can tell u all this. i done 2000 miles on mine standard, and have done the same with the pcv fitted with a full system on. completely different animal, no question this bike pulls much harder right up through the revs in every gear, and fuel consumption is about the same as the guys that tuned it actually took fuel out when mapping. i suspect the fuel economy is better but on the other hand you tend to right the bike harder because you can lol thus guzzling more fuel ::022::

I'd say this bike does fairly well stock, but it's all about your frame of reference and 'want vs need' A flick of the wrist and you're already doing illegal speeds and it's not like we need any additional passing power. That said, I'm not against a little more growl as well as increased response and more freely reving engine ::26:: It's just that sometimes I'll look back after a bunch of mod's and wonder how much is enough and was it really that necessary to spend all that money. Not preaching, but just thinking out loud. I had a KLX250 motard that I installed a large bore jug, lightweight piston, pumper carb, aftermarket exhaust, and stage one cams on, but that bike really NEEDED the extra power. Ah well, I think you guys know where I'm coming from... Stop tempting me with all these mod's already 8)