900 carb needles

[Repoman]

I have checked the carb needles in my 2003 900 1M and they are the low elevation or ZR900 carb needles. I think they were the 9DH-2-59's, will this take care of the mid-range lean spot for sure or do I still need to watch my rpms in the range some what?

I ride in ND.

Thanks

 

[diggerdown]

They help but there still is the problem of the timing being advanced a long ways. I would still vary the throttle. I think the 03' was the hottest year too, you should try to find a zr ecu.

 

[Idcatman3]

The full high and low altitude timing curves are posted in this thread:

http://www.snowestonline.com/forum/showthread.php?p=1870692

 

[Repoman]

thanks, this gives me some reference points for when I am out riding. I think I will keep the 900 mc CDI box in my sled.

 

[1Mike900]

The #3006-479 is for the ZR box that Cat recommended for the '03 MC cat to increase reliability issues below 6000" ft. Otherwise it says you can have it reprogrammed instead. '04 is when they went to a lesser timing curve, but I don't know if it is the same as the ZR's? I remember someone on here with a 975 that altered the curve to the MC900 and it really woke it up! The machine would stand straight up on the trails afterward. I am sure with the larger bore it needed a little more lead in the ignition especially with a higher octane fuel. Repoman if your riding at low elevation 2000' and below I would use the ZR box if you can find one? And keep the other if you head out west.

Mike

 

[Repoman]

When i clean my power valves, I take out the spark plugs and shine a light down into the cyclinders to see wash. The wash looks realy good, it was set-up by a arcitc cat dealer for ND when I bought it from them (dealer). If they did the proper jetting would this also lessen the issues?