Stock 04 Viper Center CYL Running Lean

sledneckdon

sledneckdon

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Joined
Oct 14, 2006
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115
Age
59
Location
Upstate, NY
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.
 
my 03 runs rich on the pto cyl. I just went 1 step leaner on jetting that cyl only.
for riding at 10,000 feet pto 145, center 147.5, mag 147.5. Runs great and plugs look even in color. If I were you i'd just adjust the jettimg to even it out.
 
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Sorry for stating the obvious, but . . .
  1. Make sure your carb is clean.
  2. Make sure there are no air leaks in the rubber boots.
  3. Possibly do a leak down test to make sure you don't have a leak in the cases somewhere.
Did this change suddenly, over time, or has it always been this way?

If it is a change, I would look for the cause instead of simply making adjustments to correct it.
 
Thanks for the tip. I am running at maybe 1000' above sea leval on the east coast with very few miles on the sled 800 max. I thought it was odd to have 1 cyl that much leaner than the others. Also, I know two other 04 Viper owners that have fried center cylenders at relativaly low miles. I will start with the jet changes. Thanks again.
 
"Low" compression on PTO cylinder is stock on the viper. My 2002 has 120, 140, 140 psi. ;)!

check the air went hose from center carb to the airfilter box and be sure that it's open and not blocked.
 
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