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Warp Speed Bug Killer
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327 Posts
Discussion Starter · #1 ·
Today I went to Cypress to ride. After I arrived at the top and slowed down, the bike shut off by itself. Subsequent up and downs were fine.

On my way home I noticed that my idle speed has increased - 1500RPM instead of 1000RPM.

Is the air on Cypress thin enough for the bike engine to try and adapt? The bike is a '03 Kawi ZX-6R.

If not then am I looking at some pending engine problems?

No "kawi=junk" comments please :surrender
 

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Twin B
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1,208 Posts
It's possible, I've noticed it at higher elevations on my VTR1000F. But it has big ass carbs and a whole lot less processing power than your bike.
I've never noticed a seat of pants performance hit, but at higher elevations the air is less dense and the bike will idle lower and have a harder time idling. if left alone it will idle lower and lower and may shut off.
I've seen this around 4000'. Cypress is around 3000', and I don't think I've had a problem.
 

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I am the liquor
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798 Posts
Shouldn't be a problem until YOU have a problem breathing, at least that's when piston-driven airplane engine start having problems. That is, over 10,000 feet. I don't know about new motorcycle engines though, perhaps the ECU decides otherwise.
 

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gix4life
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152 Posts
Don't worry about the bike not running right on cypress. Cypress will get heated out to the point that sportbikes won't even be allowed to ride up there anymore.
 
G

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Man, I hope not. Maybe you need a tune up? I could something like this happening to carbed bikes but yours is FI right?
 

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Registered
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274 Posts
i was up at cypress today too and never noticed anything different or my bike shutting off by itself.........i have a kawi too...

been up cypress a few times,,bike runs the same from bottom to top of cypress..
 

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Swivel on it
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11,659 Posts
I've never seen a difference in my engine from bottom to the top. That's what the ECU is for :)
 

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Registered Abuser
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1,017 Posts
I've been at much higher elevations without the slightest problem. I have fuel injectors though.
 

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Registered
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1,124 Posts
I took my kawi up there a few times, never reacted any differently.
 

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BMW meet Buster
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410 Posts
Shouldn't be a problem until YOU have a problem breathing, at least that's when piston-driven airplane engine start having problems. That is, over 10,000 feet. I don't know about new motorcycle engines though, perhaps the ECU decides otherwise.


most if not all aircraft have the ability to "lean" the mixture as the aircraft gains in altitude, the pilot does this by leaning according to the EGT or exhaust gas temperatue guage. Now since a motorcycle does not have that ability the mixture will ritchen as you go up in altitude!. Even a few thousand feet will affect the mixture setting so if you are running a little rich at sea level you may be rich enough at the top of cypress to cause the bike to stall at low rpm or idle speed!
 

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streets belong 2 us
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1,850 Posts
yea it makes a difference for sure. every time i go up top it takes more rpm to bring up the front wheel. someone told me the bike loses 10% of power every 1000ft or something.. not sure if that's accurate

another friend mentioned that the computer will figure it out after a while and adjust the mixture accordingly

in any case, elevation definitely makes a difference
 

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Not wearing pants.
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3,387 Posts
I've noticed a difference in altitude changes on my 03 R6. I lived in Lake Louise all summer, at 6000 feet...on trips to Calgary, the bike had a noticeable performance increase, as Calgary sits around 3400 feet. Better throttle response, faster build-up, and more power. Your ecu should adjust automatically to increased elevation by leaning out air/fuel mix, but yeah, it will be more sluggish at higher elevations.
 

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Premium Member
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11,196 Posts
ECU don't adjust mixture so all you folks suggesting that it should compensate aren't on track. This is a carb or EFI issue.

Ultra, I believe your 03 is one of the last carbed models. Yes? If so then the carbs are probably OK other than for the idle pilot screw setting that may need just a bit of tweaking to fine tune it. I've been through this on a few of my bikes over the past few years. It's something you can do yourself if you don't mind getting your hands in there. On my old 9R it meant lifting the saddle, undoing and lifting the back of the tank on a little block of wood and reaching in with a small flat screwdriver bit to move the pilot screws a 1/6 turn or two at a time to work the idle mixture. If it was out enough to matter going up to Cypress then it's likely running rich (you may notice your bike bogs and hesitates on low throttle starts) so the thinner air made it run just a bit richer and that was enough to make it bonk.

Or you may have just blown the carbon out with the run up the mountain and it was just gasping for air... :D
 

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Necessary Evil
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464 Posts
I run up Mt. Washington here on the Island all the time, and both my bikes lose power up near the top. My VTR1000 has carbs and the R1 is FI, and both lose noticeable power. I think because most bikes are jetted rich from the factory, they get even richer at higher elevations, thus losing power.
 

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ninja machinist
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3,103 Posts
+1 to what incantation said, I notice too that it takes more throttle do do wheelies at the top of Cypress. But that's all the elevation does, reduces power, an FI bike shouldn't run any differently at the top of the mountain.
 
G

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the ecu on an fi bike is able to adjust the mixture for altitude but only very slightly. not enough to compensate for serious altitudes.
 

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Ridin hard n dirty
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4,080 Posts
On a properly jetted 2 stroke M/X bike we would compensate about 1 size jet for every 1000 ft...... on a fuel injected bike the computer takes care of it...as do the newer snowmobiles.....if you are really sensitive to your bikes changes you might notice a bit of slugish throttle response.....if anything sometimes by changing elevation or on hot or cold days it is enough to highlight a problem that may be developing....take note of all the "my bike won't start" threads....weak battery, cold weather..just enough to cause a problem...
 
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