Was out at Cooke City over Christmas and melted down my center piston on my 2003 Viper Mtn. Running SLP pipes and a Holtzman ATACC. The 9500 ft elev change is a bit too much for the compensator, so I rebaselined for 7800ft with 155 mains. What I forgot to do was reset my compensator so coming from 1000 ft elev, I was lean, although the mag and PTO sides looked OK. Cracked the case open to flush remnants of the piston out. The bearings and the seal between the pto and center cylinder counter weights slide axially about 1/8" with the seal having a little wobble...is this normal? There isn't any radial bearing runout to speak of and they feel smooth. How does one go about ensuring the seal is good?
Viper Mtn Center Piston Meltdown
- Thread starter clarkegs
- Start date
Because of my Homer Simpson moment withe the compensator, the way I figure it, my compensator was comping for a 8000 ft elevation change and according to SLP's jetting chart, the 155's are baseline for 4000 ft, so my F/A ratio was optimum for about 12000 ft. This would've put me 2-3 jet sizes to lean across the board. All mains jets, pilots, needles, fuel screw were set the same...any idea why the center was running so much leaner than the Mag or PTO or is the lack of carbon on the burned down piston a result of the molten aluminum cleansing the piston?
Mag
Center
PTO
Top to Bottom Mag, Center, PTO
Mag Center PTO Top to Bottom Mag, Center, PTO
Last edited:
Vincent
New member
Did you inspect your middle carb and fuel line? Looks like the middle cylinder was barely getting any fuel at all.
Yamahakid01
New member
Correct!!!! Doesn't even look like it was running on that cylinder. I'm sorry for your lose. I live in Michigan and I bought a Viper last year first thing i did was ran it in the UP on long open trails, across lakes and thought it was running amazing. Little did i know PTO piston was burnt and the center jug was cracked wiping out the piston (previous owner)