blown motor,

ironviper

ironviper

New member
Joined
Oct 7, 2003
Messages
33
Location
westland mi
my pto went on my viper the other night, the piston is chewed up pretty good and so is the head, i havent taken the cylinder off yet to see its condition, but i took pics of the piston and head, this is my first attempt at a rebuild so and comments are welcome, im wondering what could have done this, looks like debris got in there..
 

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i added the 4th pic to show what the other pistons still look like, just wondering if i should replace all 3 or just the bad one, mypowervalve is pretty burred up also, so im a little worried what the cylinder is gonna look like..
 
it looks like a run of the mill "got to hot and chewed up a ring" meltdown, hard to tell the angle on that piston from the photo tho, I'd say that the odds are agains that cylinder making it out intact.

where you playing with jetting or a tempaflow by any chance?


edit: the wash on that center piston looks alittle cooky to say the least, did you wipe that spot clean? or was it like that when you pulled it apart. also, I assume orientation is the same as the other photo's and that the clean side is infront of a transfer port?
 
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Yep, you melted the piston and the ring broke apart. Usually its caused by a lean condition. Is your Viper piped?
Tom
 
i actually rejetted a little fatter this yr due to higher readings on my egts, and i took my tempa flow off 2 yrs ago cause i couldnt get it to run right with my pipes, unless some damage was done earlier, my sled wasnt to hot when this happened, it was right after stopping for food for about and hr, then jumped back on sled and it felt good till i hit the trail and started giving it some throttle and it started popping/backfiring, i thought it a spark plug at first so i changed it, went to pull it over and sure enough the pull rope broke on me(great night).
 
my jetting was 162.5 mains, 47 pilots, 3 clip, 2 turns on fuel screw, i was much leaner last yr and put on alot more mile and longer runs..how does my other piston look
 
i didnt happen to see it, plus i wasnt going fast at all when this happened, is it possible that some debris got in there and caused this, the top of the piston has alot of scratches and burrs
 
i'll check the carb lines again but i dont think so. also ,am i gonna have to go in to the crank and clean that out and check things out.
 
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blown motor

sounds like my problem, bought used mountain viper about 1000mi later i lost #3 cylinder and rod hair line crack in case anti nock light started coming on to late after that any one know about any used complete motors
 
I doubt it's debris man, the scratches in the head are from ring segments that got smashed into it... all the debris came from the inside.
 
im not sure why the pto went, it definitely wasnt the hottest running cylinder according to my egts, i just got done taking my cylinders off and i do believe my cylinder is done too, i'll post pics in a little while... does anybody .have an extra cylinder and head laying around they want to sell, and now i need to decide if i want to use oem pistons or just throw in a wiseco kit..
 

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Blown...

From your account of what happened it sounds like the damage may have happened before you stopped for food. I have had it happen after being well into the throttle and then slowing down and running at trail riding speeds afterwards, never noticing anything until after stopping and restarting. Actually you may have had a slight score and a broken ring for quite some time before the ring caught in the port. The cylinder looks as if it had been run awhile with a problem and it did not happen all at once. Do you remember if the sled seemed to start harder than usual after making the stop?
A close inspection may point to what happened. Another possibilty that I hate to bring up is that you had been inside eating and sabotage does happen... the pre filter is easy to pick up...
 
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the sled started fine, before and after the burndown, i actually broke the pull cord on it 2 minutes after the burndown and had to start it with some rope..it did run sluggish all day(last friday) but it was sunny and in the 40's.. i definitely thought about big boring it, but i may be buying an attak, and my viper will be my second sled, a backup for me or may let some friends use it once in a while, and i think that triple triple will be plenty fast.
 
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