And yet the end of my tail pipe is sooted black...???

 

Exhaust isn't clean


Besides...remember, this bike reburns oil from its weirdo re entry hoses and all that. Don't ever go by exhaust, go by how the bike runs. You cant even go by plug color now with the new fuels. Go buy how it runs. If it ran that much better up at that altitude, then your running way to lean down low. It should have ran crappier up at that height.

 

This doesn't sound right. Listen carefully. My bike at 400 runs perfectly, no popping, no backfiring, perfect idle, starts right up and idles after choked for only 5 seconds. It runs perfect and lots of power all the way up to 2500-3000, then it has a hesitation, small stumble, but still ok. Then at 6000 it was like the bike had 5 hp added to it. So if it was "lean" don't you think the lower it went the worse it would be? Or the higher above 3000 it would start to run even rougher? The theory doesn't make sense. That's all I'm saying. About my bike anyway.

 

Going higher in altitude will make the bike run richer. Less air same fuel. A 132 with the 331 cc at 500 feet or less would seem a little lean to me.

 

I did listen carefully.

Its not a game of more fuel good and less fuel bad. Theres a certain ratio of fuel to air that the engine burns properly...someone jump in here... isn't it 14 parts air to 1 part fuel? When at that ratio the engine is most efficient and makes the most power.

At the higher altitude the bike requires less fuel to run because there is less oxygen. Down at lower altitude there is more oxygen, therefore requiring more fuel. If your bike is running what seems to be fine, with a occasional stumble that means theres not enough fuel. When it gets up higher where theres less oxygen, the ratio rights itself with the jetting you have.

Understand?

You think this is hard, try figuring out adjust an altimeter in an airplane between warm and cold air and high and low pressure systems......its enough to make you want to cut your brain out of your head with a butter knife.

 

stoiciometric(sp) air fuel ratio is 14.7:1 at sea level---you loose 1 psi of air pressure for every 1,000 feet of elevation you gain If I remember automotive training