sledneckdon
New member
I have a stock 04 Viper and the center cyl is running leaner then the outer 2. Did Yamaha change anything in 04? My 03 did not have this problem. I know they added the deto sensor and I heard they reduced compression in one of the cylenders. Power valves are clean. Anyway what adjustments can I make to get all 3 cyl running toasty brown. Right now the outer 2 cyl are dark brown/black and the center cyl is light brown. I have heard of two other 04 viper owners cooking thier engines center cyl I don't want to be next.
Figure out where at it is lean, bottom , mid or top, and go up . If it is only on top, go up 1 jet size, if it is mid raise the needles 1/2, and bottom end you can try turning the fuel screw out to 2 1/4 turns, or go to a bigger pilot. First you need to figure out where it is lean. Maxdlx
sledneckdon
New member
What is the best way to isolate if it is lean on top, mid, or bottom??
Run it at say 6200 rpm for about 400 ft, and kill it and hold throttle where it is at until it stops then check plugs and pistons. Then do it agin at around 7500 rpm same way, then at wot. You will be able to see the difference in the plugs. Maxdlx
sledneckdon
New member
Awsome! I love getting this kind of Technical advice. I get frusterated when the dealer says bring it in and we'll get to it. Yea! and miss half the season waiting for them to get to it. I have spent the last 20 years in the Air Force working on airplanes, jets, helecopters you name it, so I am a little behind the power curve when it comes to the new 2 stroke and 4 stroke motors but with the right advice I can avoid tieing up space in the shop.maxdlx said: