I'm starting a ~4,000 mile trip in a couple weeks. It'll have me going from home near sea level, to routinely in 5-7k elevation and briefly as high as 9k. Bike is an 01 RK with the following build: 95" SE pistons, .030 HG, Andrews 21 cams, Rinehart 2:1, Ness Big Sucker. Carb is stock except for the Sportster needle.

Bike runs like a top around town, no issues. Should I consider bringing a handful of jets along?

 

I think if you're dialed in with your tune, you won't see any problems at the altitudes you're going.

I rode two different shovels from San Diego to Yosemite, via Tioga Pass (10K'), about 6 or 7 times. I never had a problem.

We had one guy out of our group, who had trouble going through the pass. He admitted that his bike was running rich at sea level.

Enjoy the trip.....

 

The diaphragm carbs adjust for altitude automatically. Not as good as EFI but still enough you should be fine.

 

Good question, my buddies 02 RK with a 106 S&S blubbers and gets bad gas mileage at higher elevation. I rode the highest paved road on the continent, Mt Evans at 14270, and lowest in the US, Death Valley at - 280 in the last few months and it ran flawlessly. But that is with EFI

 

OP you'll be fine.

the Keihin CV ( Constant Velocity) carb self adjusts for changes in air density whether temperature or altitude...or weather.

The size of the hole is determined by the air rushing through it and pushing the slide up...thick air= big hole/ thin air= small hole.

the needle is held by the slide...the farther the slide rises ( big hole) the more fuel is added to the air...if the slide doesn;t rise much ( thin air/small hole) less gas is added.

My evos regularly run from 1200' to 8000' with some 11's too.
My 80" evo will leave mikuni'd and S&S'd big motor bikes way behind- those carbs are fixed.

enjoy your trip

The CV carb often outperforms the M&M and Delphi EFI measured for Power, MPG and emissions.

Mike

 

Thanks guys. Great point MK - I know how a CV carb works but I had completely forgotten that it can account for changes in air density as well. I'm feeling pretty confident it'll be good now.

Should be a great trip - Milwaukee area through Missouri, Oklahoma, and north Texas to Upper New Mexico to Flagstaff, then up to Moab, then down through mid Colorado to Colorado Springs, home through KC and Iowa. First two and last two days will be pretty boring "just get there" days, but we're in AZ for 4 days, UT for 2, and CO for two.

 

make sure you go through Monument Valley:




I often stay at the San Juan Inn in Mexican Hat, from there you can take #261 and go up the Dugway ( gravel) toward Natural Bridges Monument...swing East toward Blanding and N to Moab.

Dugway:







If you are doing the GC, Best Western does a hOG discount and is probably the best food in town...bowling alley in the basement level

Expect temps up there to be in the 40's/50's at night.

Elk are always a concern late aft into night in any wooded areas- their eyes do not reflect ( like deer) all you'll see is a tawny patch on teh rear- loud pipes do not scare them...I am usually done riding by 5 ish.

Central CO is good, very good, just came back.

Until mid-Sept we are in Monsoon season watch for late afternoon storms coming from the SE. These usually blow through fast and violent. Just wait it out

mike

 

I agree with MKGuitar, if you want a fun ride make sure to ride 261 and take the Moki Dugway.
Monument Valley is also a cool place. We stayed at 'The View' lodge in the reservation.

 

Damn... you guys are killing me about the Utah leg....!!

When I went through Utah in 2012, the temps were over 100 degrees.... It was like driving a car with the heater on full...

I didn't stop or deviate from the main route all through Utah. I knew I would regret it...

But when I packed my bike to leave Moab at 0700, it was already 90 degrees....

Although I went by Monument Valley, it was at 75MPH and the only pics are in my head.

I'll have to go through there again for sure....

 

My experiences with CV carburetors in general is that they handle altitude changes just fine. The thinner air will reduce power and gas mileage and create an increasing throttle snap bog, but by no means render the machine undriveable/rideable. I'd have to usually get upwards of 12000 feet to start running into appreciable driveability/rideability changes.