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Discussion Starter · #1 ·
First time out in our 21 KRX to Colorado high country. The engine is very sluggish above 9000 ft and it gets much worst on up. Is there a fuel controller or reflash that will help!!
 

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2020 Kawasaki KRX
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Guess I must just not know any better since I live in Colorado and all my riding is from 8,500' and up. lol Mine runs fine at high elevations.

4509
 

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Welcome to the forum. Power loss at altitude is about 3% per 1000ft. So at 9000ft you have lost 27% of your HP or about 30 HP. A tune will only gain back 3-4 HP at that altitude. The only real solution is forced induction.
 

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I found out while riding around Lake City and Silverton that any time I got real high I needed to loosen the gas cap and let the tank vent. It even got to the point that my riding buddies would do it for if they were close when we stopped. It sounded like a jet engine when it was cracked open. Pretty sure this will affect performance! There is a cheap cure available, a rollover vent valve installed in the tank vent line seems to do the trick. Ordering mine Monday.
 

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Gas cap is likely just a one off issue…

At those kind of elevations is where a properly tuned turbo car shines. With NA there is not a lot you can do to overcome the loss in air density. It is what it is. With a turbo you can lean on it a little harder (in the tune) to compensate for loss in air density.
 

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The gas tank vent problem is well known even at low altitudes. There's a Facebook forum for the KRX and a large group of the members are southeastern trail riders. Hatfield McCoy, Black Mountain, and many others. That was how I learned about it. I am surprised that I haven't seen it mentioned here.
 

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The gas tank vent problem is well known even at low altitudes. There's a Facebook forum for the KRX and a large group of the members are southeastern trail riders. Hatfield McCoy, Black Mountain, and many others. That was how I learned about it. I am surprised that I haven't seen it mentioned here.
I think a lot of us that have done the mod take it for granted and just forget to mention it.
 

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Yes it’s literally the first mod I did.
 

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First time out in our 21 KRX to Colorado high country. The engine is very sluggish above 9000 ft and it gets much worst on up. Is there a fuel controller or reflash that will help!!
Wow I was just on a 122 mile trek with 1/3 of it about 9000 feet and the highest at 11,672. In general no problems.. actually up to 60 MPH above 11,000 feet!
 

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Discussion Starter · #13 ·
I have ordered the rollover valve and will try it. My KRX behaves like it is in low power mode from 9000 and up. It takes half the throttle to make the machine respond and then it lurks ahead and if you let it drop below 3500 rpm it bogs and loses power quickly. If you gas it it goes at it again but slowing is the same it tries to die. As you descend the performance picks up again to normal. I understand the effects of alt. on natural aspirated engines but this is much worse. Any advise?
 
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