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Discussion Starter · #1 ·
'11 NightRod Special... K&N air filter, no airbox lid... currently, 2-to-1 Danmoto slip on exhaust, going to straight pipes. I usually ride all the time between 6500 - 9000 ft. Is a tune really needed since I'm doing all of my riding at altitude?
 

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'11 NightRod Special... K&N air filter, no airbox lid... currently, 2-to-1 Danmoto slip on exhaust, going to straight pipes. I usually ride all the time between 6500 - 9000 ft. Is a tune really needed since I'm doing all of my riding at altitude?
If the bike was tuned at a lower altitude, absolutely. The ECM can only compensate so much and you are likely past that point.
Ron
 

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Discussion Starter · #3 ·
My thinking is that it has a stock tune. At elevation, the ECM will compensate, it should run toward the rich side. By opening up the air box and exhaust, allowing more air in, it should help lean it out. When removing the slip on Danmoto exhaust, replacing with just tips, it sounds and feels good. Very minimal popping if any on quick throttle release / de-acceleration.
 

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Vic Jacoby
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^^^^^ what Jan-Dirk said. I live and ride around sea level, but I've been out to the Smoky Mountains on my bike a couple times with no issues.
 

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IIRC, the ecm essentially takes a "snapshot" of barometric conditions whenever the bike is started and it uses that snapshot until the next time the bike is started.

So, if you were to (theoretically) start the bike at sea level and ride straight up to the top of a Fourteen'er here in CO, you might have issues.

In the real world? Don't worry about it.
 

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IIRC, the ecm essentially takes a "snapshot" of barometric conditions whenever the bike is started and it uses that snapshot until the next time the bike is started.

So, if you were to (theoretically) start the bike at sea level and ride straight up to the top of a Fourteen'er here in CO, you might have issues.

In the real world? Don't worry about it.
To a point . Map sensor will do it's thing but without O2 sensors the bike will run much richer, and the same if PC3 is used. There is a max amount of compensation, however the op is within this range since he should be close loop in the tune. Open loop as in earlier v rods won't have O2 compensation for fueling and will run much richer at elevation. Same as a carb, if in open loop.
Ron
 

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VRSC est -03
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Starting at sea level, how much affected would afr, open loop be for every 2000ft elevation? Anyone?
Nah, not my Sporty, but looks crazy cool.
 

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Autobanmod
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Starting at sea level, how much affected would afr, open loop be for every 2000ft elevation? Anyone?
Nah, not my Sporty, but looks crazy cool.
https://de.wikipedia.org/wiki/Luftdruck
0 m 100 % 1013,25 hPa
100 m 98,7 % 1000,3 hPa
200 m 97,5 % 987,6 hPa
300 m 96,2 % 975,0 hPa
400 m 95,0 % 962,5 hPa
500 m 93,8 % 950,3 hPa
600 m 92,6 % 938,1 hPa
700 m 91,4 % 926,2 hPa
800 m 90,2 % 914,4 hPa
900 m 89,1 % 902,7 hPa
1000 m 88,0 % 891,2 hPa
1500 m 82,5 % 835,8 hPa
2000 m 77,4 % 783,8 hPa
2241 m 75 % 759,9 hPa
2500 m 72,5 % 735,1 hPa
3000 m 68,0 % 689,4 hPa
3500 m 63,8 % 646,5 hPa
 

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Autobanmod
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The AFR is not being affected due to the BARO compensation.
If I recall it correctly then this is being constantly updated while engine is running.
 

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My thinking is if you are going to straight pipes or even sticking with the DanMoto and have never had it tuned, then I would start with at least a decent map for what mods you have. I understand your thinking but it is guess work at best..
 

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'11 NightRod Special... K&N air filter, no airbox lid... currently, 2-to-1 Danmoto slip on exhaust, going to straight pipes. I usually ride all the time between 6500 - 9000 ft. Is a tune really needed since I'm doing all of my riding at altitude?
You need to retune the ECM when changing anything in the intake or exhaust that affects the VE (pumping efficiency) of the engine. This includes things like camshafts, velocity stack length, exhaust pipe geometry, displacement, etc. Changing to lower restriction air filters alone can be handled by the MAP (manifold absolute pressure) sensor. This MAP sensor also compensates for altitude (and weather) changes, as Jan-Dirk mentioned in Post #4. I don't see how riding at high altitude eliminates the need to correct for VE changes. The VRSC fuel injection can't be compared to carburetors (or older mechanical injection systems) that don't adjust for atmospheric pressure.
 
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