Elevation changes

I am looking for some feedback here with my fuel screw. I am jetted for about 3,000 feet elevation. Im at 1 3/4 out on fuel screw and don't have the other numbers right now, but runs fine there. At 6,000 to 7000 feet I ran rich even at 1 1/2 turns out.( Plug was black). I don't go there too often and don't want to change jetting. Any sugestions for my next trip? 1 1/4 out?
Just trying to see if there's a common number here that equals elevation. Like a 1/2 turn in for every rise of 2,000 feet or something. I know the right way is to re-jet for extreem changes.
Pollo

Hi Pollo

Elevation changes are hard to adjust for with a rule of thumb. I always run an easy adj screw, the kind with the knob. Then I turn it back and forth till I find a setting that works. Elevation is one factor due to altitude and its inherent pressure changes, but you also encounter temp changes with the altitude changes, humidity factors and pressure differential due to wind, ie a venturi effect on the back side of a mountain. I've adjusted 4 or 5 times in a day if I'm being fickle, and sometimes you need to if your in technical terrain. Run good fuel and use the easy adj knob...hopefully you can find a something that works for you.

Hi Pollo,

Keeping in mind that the range of the ps is between 1 & 1/4 turns out and 2 & 1/2 turns out......

If you want a good starting point, with bike warmed up fully and idling normally, turn the ps in until the motor starts to slow down, then back out 1 turn to 3/4 of a turn and that should put you in the ball park.

If the motor won't slow down or die when you turn the ps all the way in, the pilot jet is too big. If you have to open the ps to 2 &1/2 turns out then you could probably use a richer pilot jet.

If you haven't already, you might have a look at the doc and check out the paj and pj chart. Once you have this set right 1/4 turns to the ps will reap big changes in how the bike is running as you will have the air ratio set right for a given pj size. For instance, I have a adjustable pas or paj in my bike and it is set for the 38 pilot that I have in my carb. During the winter in the desert, my ps is set around 2 &1/4 turns out, and yet I can go up to 9000' and it can be 80 degree's and I'll be down around 1 & 1/4 turns out.

Of course, you also have to make sure that you have the right needle straight on your needle etc...

Since you mentioned changing altitudes, and Fry mentioned not changing altitudes but changing pressures and temperatures, which is also known as "density altitude", I have included the linked density altitude calculator. If you use the noaa.gov site and pick the nearest weather station to your favorite riding locations, you can get the required inputs and check out what the density altitude changes are. It might surprise you how much higher in elevation the motor thinks it is based on temperature, humidity, baro pressure, and altitude.

http://wahiduddin.net/calc/calc_da.htm

Thanks for your time and input. The bike is running great right now. I checked the new Denso after Saturdays ride. Elevation around 2,000 ft. with temperature about 70 i'd say. Fuel screw was 1 3/4 and it ran well. Plug was a light tan. Today I ran it after work at sea-level 1 7/8 out for 20 minutes. Ran great and plug remaining tan. ( It is still a little white on one side though)
I will leave it there for the next 2,000 elevation ride to experiment with it. I'll see and check plug later. If I like it and the plug remains tan to brown i'll be happy.
On a slightly different note, today during my test ride I was riding through downtown some and this lady decides to take a left hand turn from the rght hand lane right in front of me!! I nearly locked it up but had a good front brake going. I ended up turning left with her to prevent a collision. Then she and her other old lady friend look at me like it's my fault!
All I said in a loud tone was "ARE YOU ALRIGHT? !!" Since I don't cuss, even when I'm real mad. And the meaning was "Are you are rght with your brain?!!"
You can't be too careful on the road guys. I hope the best for all of us when street riding.

Pollo

I'd just point out that a plug reading (color) really is only useful for diagnosing a WOT run (main jet).

You are going to be chasing your tail trying to jet the needle and the pilot/fuel screw by looking at the plug color. It won't jive.

Well, I did have the jetting done professionally and thats about where it sits since I had it done. So I can't take the credit for it being jetted properly. As far as plug color, well I admit I didn't know that much but then again I have mostly relied in the past with feeling the bike run and can tell when its running lean or rich. I know the lean surge that comes with running to lean and have known the rich blubber accompanied with the drop in idle. I know these are to the extreems but you get to know your bike after riding it for awile
I was told by the guy that jetted my bike that to get to a starting point when setting idle screw that you turn it out until you reach the point of the highest idle, then just nudge it back a hair. That should be about right. Of course it helps to already be close and then find this spot. So I have tried this before and it does seem to be correct. Dale had a different way that probably works fine, The guy that told me has been doing this for a long time
Pollo