Center cylinder burn down on viper

sdahm

sdahm

New member
Joined
Oct 18, 2009
Messages
68
Age
32
Location
Wisconsin
My center cylinder burned up on me a few days ago and wanted all of your opinions on why it maybe happened. I'll post some pics below. The cylinder took a beating too. The other two cylinders look normal though. What could have caused oil flow to stop or slow down to the center cylinder? oh, and the day before my warning light came on my sled so i shut it off for a few minutes, and started it back up and it never came back on. Rode almost 200 miles and then this happened. Shouldn't my temp light have come on?

www.reflectivemediaproductions.com/tj/pictures/viperburn1.jpeg

www.reflectivemediaproductions.com/tj/pictures/viperburn2.jpeg

Scott
 

looks like a lean burdown to me not an oiling issue. or maybe an overheat. not much coloring on your piston tops. check your carbs especially the pilots. and check for any air leaks. do you have any pics of the other 2 pistons
 
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how does the rod bearing look/feel? where in wisconsin are you located? also, i have a used cylinder if you need 1 to get back up and going.
 
The carbs are clean. I clean them every year. About 400 miles ago I was having a bogging issue so I took it to a shop by me cuz I thought it was electrical. Ended up being a small bit of corrosion that I somehow missed under the bowl's rubber ring that got into the pilot. It was running on 2 cylinders until 4500 rpms. And the shop cleaned and set the carbs again for the second time this season so they should be good. I'll open em up again though and take a look incase something else went wrong.

I don't know what the rod bearing/ feels or looks like. I don't have much experience digging this far into 2 strokes. I know how to do it, i'm just not experienced. I wanna learn!! This is my first time going this far. How do I check or get down that low in the bottom end to check. I don't even know how to get the piston off the rod lol. I wanna put all new rings in the other two cylinders while it's open. Almost 5k on the sled. I'm located in Belgium! 25 min south of Sheboygan only. I may have to take you up on that. Keep in touch!

Here's pics of the other pistons. Should they look darker? Recommendations on where to buy a piston, and all new rings?

www.reflectivemediaproductions.com/tj/pictures/viperburn3.jpg

www.reflectivemediaproductions.com/tj/pictures/viperburn4.jpg
 
Oh and the head had some aluminum on it, I go to college in Madison (2 hours from home) so I cant take a pic of it. I forgot to yesterday. Will I need a new head? or can I do something to it?
 
Is piston wash black areas from burnt oil?

So this is looking like a carb issue?
 
piston wash is areas by the transfer ports, that are washed clean to the aluminum crown. to indicate safe trail jetting, you would want wash marks the size of a pencil eraser, to the size of your pinky nail.
 
If the damage isn't too bad you can sand the damage enough to make it smooth..... it would be best to get a new head though!!!

It almost looks to me like the piston hit the powervalve..... the damage kind of has a point and curve pattern to it like the shape of the PV...... how does the PV look???

someone help me out here is this even possible???
 
I didn't look very close at the powervalve but I did pull it out and it did have aluminum on it. I don't remember it looking like it was damaged though. It pulled a little harder than normal to get out though.
 
Pure and simple, that piston suffered detonation. Go look at automotive sites if you doubt it.

Viper has a known issue with low speed localized heating and detonation. If you rebuild it don't put it back together without an Opticool head gasket from Bender. Then set needles one step richer. Oh, your temp light will not come on with most forms of detonation.

One more time guys, top of piston sand blasted away on one area is detonation.

By the way, my Viper with only 21 miles on rebuilt engine towed my 700lb apex out last sunday over 10 miles. I guess the needle setting and opticool gasket are working! :mrgreen:
 
Thanks for the info. So is there anything that I did wrong while cleaning my carbs? Or anything that the shop did wrong that worked on this right before it happened? Or is it just something that happens?
 
Maybe they did something wrong but doubtfull. Do a search for blown engines and see many others like you. Must use opticool head gasket (or 400 dollar head upgrade) and richen carb needles then you are ok.

Only takes a few seconds of detonation to blow a piston. And the crappy gas this year is making the detonation problem worse. I did not know the above facts and burned down a piston in a Viper with 823 miles. NOW I have the Opticool gasket and needle richened.

Oh, and I forgot to say the Viper has a severe spark advance curve the machine this engine was originally built for did not have .
 
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