Thread: Thar She Blows
04-01-2007, 07:44 PM #1
Thar She Blows
Well after 2+ years of not even riding the Polaris and hate to see it collecting dust, pulled my heads today. I kinda knew that I would have some issue becuase the last person that rode it was my buddy's son's friend, who was thinking he's some freestyle pro, would air it out but stayed on the throttle. I was yelling to him to not do that but was too far out to hear me. Managed to smash the pto plug. It was the last ride late in the the day more than 2 years ago. It was actually the Fri. of the 04 World Finals and Sat and Sun I was at the Finals so I didn't get a chance to check out the cause of the smashed plug. Like I said, it sat since the 04 Finals. I have been riding Fri. and Sat. and this morning before heading home, I decided to pull my heads off the 780. I started from mag to center to pto. Mag and center were fine and then I pull the pto. Yikes! Looks like someone shot a shotgun round off inside my combustion chamber. Love the nice perfectly round bb imprentations Has to be a crabk bearing that went but everything moves up and down smothly. I'll have to take the rear cylinder off next time to see what's going on below.
My diagnosis is that the idiot was revving to the moon by holding it wot out of the air and holding wot when hitting the water and just excerting a lot of pressure on my crank. He was doing this for a good 15 minutes. My buddy's son is no longer friends with the kid so I can't even vent to him. I usually don't let newbies ride my baby butI didn't expect him to think he was Evil Kneivel trying to jump the grand canyon on my ski. I thought he would just ride it somewhat normal and not like a bucking bronco. It does have quite a bit of acceleration and it is fun to launch it, but you have to let off right before hitting the air and get back on it when landing. I never dreamed of explaining that to him before going out because I didn't think it would even be an issue but it is all he did for the whole time out. My waving hands and screaming mouth were not noticed when I heard the painful sounds that he was making with my ski.
Here are some pics. Since I talked about my head mod in another thread, I took some pics with the the custom cut stock head gasket and the o-ringed head mod that I have. It is a really trick set up. The custom moded stock head gasket is reuseble with some copper spray and keeps the stock cooling flow. The combustion chamber is sealed with an o-ring. The head is also moded to allow the head gasket to sit flush with the head (this is kind of hard to see though).
I'm thinking of parting it out but might fix it? I have lots of great performance parts on it and this ski was a blast to ride!
04-01-2007, 07:51 PM #2
Damn......those indentations are wild!!
I'm like you, I really try to keep guys/gals of of my stuff. Some know what they're doing but the others just don't care to understand.
If you're going to sell it let me know, you're not that far away and I have a nice 800 twin waiting for a new home.
Killer piston wash by the way.
04-01-2007, 08:00 PM #3
Man thats some great pics!!! I would shoot the kid and keep the ride!!! (Shoot that little ba@tard with a BB gun) LOL.
04-01-2007, 08:12 PM #4
Al, I have it dialed in pretty good and I have yet to seize an engine. This set up ran flawless for me and I was always on the gas going wot. Well always except when in the air, lol. If I decide to part, the hull is great and has the Matrix that never was look before the Matrix was mentioned
I forgot to mention that the cylinder wall seemed fine on just visual inspection, although the garage is dark in the back where I have it sitting. I didn't have a flashlight with me at my AZ home where I keep it to inspect any closer. I'll pull the cylinder next time I go ride. Just when I was getting the itch to run some gas through the 780, I get this.
beer, I want to bb gun the kids arse.
Last edited by SeaLion; 04-01-2007 at 08:15 PM.
04-02-2007, 08:03 AM #5
- Join Date
- Aug 2006
- Pittsfield, MA
WOW! Never seen one like that. That sucks! Anyway seeing how it's been sitting for two years I'm guessing you'll be at the very least cleaning your carbs before you head out with it again. Inquiring minds would like to know what size jets you're running in those pro carbs for the future dry pipe swappers.
04-02-2007, 10:17 AM #6
I suspect big end bearing from the nice round impressions. Something smaller in diameter left less noticeable impressions too. I think the plug smashing was done by the object and not the piston top hitting it as there are no signs of piston damage other than the round impressions in 2 sizes. It also blew out the exhaust because there were no pieces in the top end that I could find. All 3 pistons move freely by hand with no binding whatsoever.
04-04-2007, 02:00 PM #7
Thats not crank bearing. Something else went thru the engine. In order for a bal bearing from a crank bearing tho get to the top end, the bearing cage has to come apart and there isn't any sign of metal pieces. It looks like something went thru the carbs and in. Make sure that you carb plates and reed assys have all their screws still attached.
04-04-2007, 03:10 PM #8
Bruce, I was kind of thinking the same thing queitly. The cylinder wall looks good too as well as the pistons moving freely and without any binding when done manually. The only thing that throws me off is the perfectly round shapes and in 2 sizes with different depths for each. It doesn't look like anything that would come out of an intake system. I definitely will be pulling the intake next time I am at the house.
04-04-2007, 06:56 PM #9
- Join Date
- Aug 2006
Last summer I saw a bearing from a sea-doo that somehow lost a ball, looked almost identical, and their wasnt any signs of other foreing material damage.
Never figured out WTF happend, just sat and stared at it......still bugs me.
04-04-2007, 07:33 PM #10
That is strange. Did you run it more or get a rebuilt crank? You figure if one ball came out, more would follow.
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