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Old 10-03-2008, 02:26 PM   #41
SecretAgent
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Quote:
Originally Posted by po-po 5.0 View Post
Yup. I have much less experience with bikes, but I know plenty of car tuners who give you pretty little charts with high numbers on them and the cars either run like when you're actually trying to drive them or put up poor results when it counts (because the power was way too peaky to be useful or the numbers were inflated by dyno trickery).
this is common because most tuners use an inertia dyno (the everpresent dynojet) which is incapable of tuning for driveability, only for max power. you can only do full throttle runs in single gears. on an eddy current dyno you can tune for any throttle position in any gear, at any load level (generally a load equal to the load the car/bike would face in the real world). without an eddy current dyno, the only way to accurately tune the other parts of the powerband besides full throttle, a street tune is necessary.
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Old 10-03-2008, 03:09 PM   #42
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Quote:
Originally Posted by SecretAgent View Post
wow lots of misinformation being spread around this thread....here's the skinny.

a PC3 is a piggyback system that fools the ecu into thinking the bike is running leaner/richer than it really is. it does this by intercepting the signals from the various sensors on the bike (coolant temp, throttle position, gear, speed, etc) and reinterprets them to make the ecu change the signal it sends to the injectors, according to how much fuel you want added to taken away.

it's a fairly simple system, but can be tuned to work quite well. however, the pc3 doesn't factor in a lot of different variables, so there's no perfect tune with a pc3.

oh, the dyno run. it's done in 3rd or 4th gear (usually tuner's preference) on a common inertia dyno (dynojet, mustang, etc) to prevent loading the engine too much and possibly blowing the engine. it is NOT ran in top gear like others in this thread were saying. however, on an variable load dyno (such as the factory pro), the tuner can run the bike in any gear he wants because the load put on the bike is variable, according to conditions and tuner input. he can even hold the bike at certain rpm's and throttle positions to get exact hp and torque readings at that rpm and load to fine tune the map perfectly. ALL proper dyno tuning is done with a wideband 02 sensor hooked up to the bike's exhaust. not just by tuning to find what settings make the most power. this can lead to the bike running very lean and grenading, or causing on/off throttle sputter and other driveability issues.

as for the k8 1k....it has 3 fuel maps, and about 18 different ignition maps. but since the pc3 is a piggyback, it doesn't really care, nor matter. the bike is still running off the same maps it always has, it's just the signals before and after the ecu that are being modified. the maps stay the same, the pc3 just changes what parts of the map it's using, again, by fooling the ecu into thinking it's running differently than it is. the biggest downside to all of this is, if you make major changes to the bike (motor build, turbo, nitrous, etc) the ecu doesn't have a broad enough adjustment range from stock to compensate for these changes. the factory ecu can only adjust the fuel injector duty cycle (how long the injector fires) +/- 50% of stock. and yet another downside to the pc3 that many people, including a lot of tuners, don't realize is that when you trick the computer into running different fuel numbers, you're also making it run different ignition timing numbers. for example, say at 65% throttle and 8900rpm the stock bike runs fuel cell F9 and timing cell I9 (they are directly related to eachother because that's how the engineers programmed the ecu to work) well, when you make the ecu think it needs fuel cell F11 at 65% throttle and 8900rpm, it now also thinks it needs ignition cell I11. by attempting to adjust the a/f ratio, the tuner is inadvertently changing the timing as well. now this could be beneficial or detrimental, but without knowing exactly how the timing is changing, there is no way to counteract this effect. unless you also get the ignition module for the pc3, which will again, intercept all signals and modify them to suit the tuner's needs. see how this can get cumbersome and inaccurate now?

the selectable switch on the k8 selects different fuel maps, not adjusts the secondaries. although for each map, the secondary routines are different, they are not the sole factor in why the bike runs differently.

now, if i've explained how the pc3 works well enough, you should be able to understand it's shortcomings by now. the Yoshi race ecu has none (besides price). it is a true replacement ecu that unlocks the potential of the bike's engine and electronics. it allows direct control of both the fuel and ignition maps, not just their input signals.

let me know if ya'll have any more questions, or if you need me to clarify anything i've said.
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Old 10-03-2008, 03:10 PM   #43
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Is there a shop in town that uses a Factory Pro dyno or equivalent?

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Old 10-03-2008, 03:11 PM   #44
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Quote:
Originally Posted by maxgs View Post
Stellar response. SecretAgent, next time we are at a M&G together, I owe you a beer for that one!

-Curt

read some of my posts. Some of the info he posted was incorrect.
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Old 10-03-2008, 04:51 PM   #45
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Quote:
Originally Posted by maxgs View Post
Is there a shop in town that uses a Factory Pro dyno or equivalent?

-Curt
Yup, one in the Heights... Metric Motorcycles.

www.metricmotorcycles.com
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