This is outside my experience, but I'd say that if you got your carbs running right at 5000 feet, they should work OK at 9000 also. At least the error at 9000 feet will be on the rich (safer) side.

First, have the carbs been cleaned thoroughly? It sounds like they need it.

Parts can be found here in stock and resonable:

I have bought from them for my Dell's.

The Dellorto is an excellent carb when set up properly. Easy to work on and set up.

Since the Dellortos did not come on your bike stock, you may find it difficult to find cables off the shelf. Many good bike shops will make you cables, or you can send your old ones to Motion Pro, and they will make you new ones. http://www.motionpro.com/ Adding elbows to the cables where it enters the carbs works nicely on my Sport.

Do you know what jetting you have in the carbs currently? Sounds like your pilots are bit lean, but it may be just a bit of cleaning needed. If you haven't already, adjust your idle mixture screws about 1.5 turns out and see if that changes anything.

Current jetting in my 36 PHM Dellortos on my 1990 Sport with 2into1 exhaust
155/158 main (richer in back)
60 pilot
265 atomizer
K5 needle in middle postion
60/4 slide
Champion plugs

I also screwed on the Dellorto plastic velocity stacks (also known as trumpets). Onto that I put on two 2-inch rubber elbows to make a full U-turn to reach the 8" foam UNI air cleaners. I found the 2" rubber elbows at Air Flow part#90HL2 Rubber Intake Hose 90 Degree 2" $8.87 http://www.airflowonline.com/

The rubber hoses act like an airbox and improves idling and low end by containing the fuel fog coming back out of the carb between pulses. It also makes much better laminar flow which generally improves carburation overall.

Hope this helps.

Nemesis,

Which Dell Ortos have you got ? My bike has had PHM 40s for about 17 years and Johannesburg is at 1,600 metres (5,000 ft). I am pretty sure one of my previous posts contains my jet sizes. If not, I want to have a good poke around when I get it back from storage tomorrow, although it might take a while for me to get around to looking at the jet sizes.

Paul