Hello everyone, Family moved from Illinois (flat) to Colorado last August the elevation is 10,150ft where i live now. My 04 HD FXD runs good if on flattish land here but if i go up these steep highway roads my bike almost dies or will die but I rode the bike on the steep hills when started getting cold here (50 degrees or less so not sure if it was doing it when it was warmer out.). I figured that the float and carb is messed up in some way and I am getting ready to order a float and a carb rebuild kit but not sure if i need to get better jets and needles and i am really not sure about the mixture screw I have never messed with it. Any help would be appreciated as i would like to get it back in great riding condition for up here around beautiful Leadville. So with living at this high altitude is the mixture screw about the only thing i will have to adjust besides doing the rebuild kit? I do have the shop manual but it is still in few of the moving boxes and not sure where at atm.

Thank you
Chris

 

The bike needs to be tuned, in other words it needs to be re-jetted for the thin air you're running in, take it to someone who knows what they're doing on adjusting carbs. That will help out a lot, but you're just going to have to get use to it not having as much power as it did at lower elevations, ie 30% less air = 30% less power.

 

Thank you for the reply DTTJGlide, I will look into and learn more about getting the carb re jetted for up here. Thanks again for the help

 

The float level isn't affected by altitude but the mixture is the culprit. As previously mentioned get the slow jet and main jets looked at by a shop that's experienced in rejetting for the altitude.

 

Thank you very much for the help. I have not found a mechanic close to where i live. I will probsbly just have to order the stuff and do it myself.
I was wandering what size carb jets i should be looking for? I will be buying the carb rebuild kit,jets and air/gas mixture screw. What else would i need for the carburetor and my bike to run without losing all my power?

Thank you
Chris

 

Chris,
Do you have a CV carb?

 

Actually a metric motorcycle shop that deals with trail bikes or ATV's may be able to help you in you re-jetting. I think you would need to reduce the amount of fuel to match the reduced air available going into the carb, so you are in need of the jet changes.

 

If the bike is only going to be staying up there at the higher elevations, you can raise the compression and make up that lost power.

Dave

 

First thing you have to consider is, at that elevation, you're just not going to make the same power as you do at sea level. At 10,000 feet you're going to loose 30% of your available sea level horsepower due to reduced manifold pressure. This alone could be the majority of your problem. (47 hp available)

CV carbs are pretty good at self-compensating for pressure changes. The only real problem is going to be at the extremes, (idle and full throttle) where the carb is not acting as a constant velocity carb. Sometimes, all you need to do is lean out the idle setting a bit. At 10,000 feet you could probably benefit from a slight reduction in the size of the main jet at full throttle, but I don't know if it's even worth the trouble, and the risk that if you go down lower you're now too lean. You could try going 1/4 turn leaner and see how much that helps.

I would suggest calling the dealer in Denver and seeing what they recommend. If you need different jsts. there are plenty of places to get them. Jets-r-Us will ship you whatever you need if you want to go that route.

[edit]Raising the compression ratio can get you back some of the lost power, but, bottom line, to make power you need to burn fuel, and to burn fuel you need air. Unless you are willing to supercharge the intake, you can't ever get the majority of that 30% loss back.

 

Pilot. Smaller
Needle lowered
Main jet smaller

Bike is running to rich due to decreased air density.
A single CV carb is simple to tune. Check with FactoryPro or Dynojet