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Discussion Starter · #1 ·
So i pulled the head off the motor on my 2000 ZR700 (7,900 miles on motor) today to find out what was wrong with it. initially i thought the piston had hit the plug due to piston slap or a bad bearing...well, i was wrong.

from the looks of it, the top ring rotated in the groove and caught the transfer port. causing the ring to bend up slightly and break off a good size chunk of piston. there is absolutely no damage to the motor other than the broken piston, the head is fine, the cylinder is perfect, even the top of the piston has almost no marks from the chunk of aluminum ratting around in the cylinder.
not only does it still run, but it has 98 psi compression in both cylinders and i drove it 35 miles back from when the plug gap had gotten pushed closed by the broken off piece of piston. i just threw a new plug in a drove back.
this old 700 twin really is a tough motor.
now for the pics.
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Wow, you got lucky it went right out the exhaust, instead of finding its way to the bottem end. Should of played the lottery that day you probally would have one
 

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Discussion Starter · #3 ·
i got real lucky on sunday. we managed to find good snow in woodford and then this...i really shouldve played the lottery. haha
 

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hahaha hell ya thats a step above luck
 

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Discussion Starter · #5 ·
thats the best luck ive ever had. usually when $hit goes wrong it turns into a grenade, but i guess god wanted me to finish my last ride of the year without being towed back.
 

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Glad the old girl is in good shape.[;)]

Are you going to put new pistons and rings in next Fall? I would think a chunk like that missing can not be good?
 

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Discussion Starter · #7 ·
yeah, im gonna do a top end in the fall. and a chunk like that missing is one of the worst things that can happen to an engine. lol
 

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ilive4snow700 said:
i got real lucky on sunday. we managed to find good snow in woodford and then this...i really shouldve played the lottery. haha
Woodford? In your state or another? I am curious where there is still snow anywhere around your state.

EDIT - didn't see it in your status
http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=woodford+vermont&sll=42.992732,-75.6888&sspn=0.797558,2.113495&ie=UTF8&hq=&hnear=Woodford&ll=42.932296,-73.377686&spn=3.193309,8.453979&z=8

How much was there? Where?
 

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Discussion Starter · #10 ·
woodford vermont had good snow. we trailered to twin brooks ( http://maps.google.com/maps?hl=en&um=1&ie=UTF-8&q=twin+brooks+woodford+vt&fb=1&gl=us&hq=twin+brooks&hnear=woodford+vt&cid=0,0,2428902489312980325&ei=TbGzS4ewA4GKlwfwhrC7BA&sa=X&oi=local_result&ct=image&resnum=1&ved=0CAcQnwIwAA ) and rode on trail 7 most of the day. feeder trails and low elevations were pretty muddy, but high in the mountains on the national forest roads there was 2-4 feet still and groomers had been out every night. ....but that was on sunday. after the rain they had the past few days its pretty much done, unless you can find a way to get to the high elevations, and even then there wont be much riding left.
 

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WOW, there was still snow in Woodford?![:0] FOr those that dont know, which is most everyone, Woodford, VT is in southern VT, in the mountains. And considering the location, they get a freakish amount of snow there. When there is 6 inches of snow everywhere else, there could be up to 3 ft in Woodford. I rode there once in mid Dec. and it was GREAT! Every time I ever drove through there in the winter they always have bigger snowbanks than everywhere else.
 

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ilive4snow700 said:
thats the best luck ive ever had. usually when $hit goes wrong it turns into a grenade, but i guess god wanted me to finish my last ride of the year without being towed back.
Haha he has favor with you.
 

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Have you pulled the piston yet? You said the ring spun in the groove.
I'm curious if the ring locating pin is gone.
 

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With the amount of miles on the sled and the fact that part of the piston went somewhere I would tear it down completely and get the crank bearings done put in new seals and clean out the crank case real well...it looks like your sled is real clean so why not put a little more money into it and do it right and have another 5000+ trouble free miles? just my .02 cents
 

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Discussion Starter · #15 ·
i havent pulled the piston yet. ive been too busy getting the boat and jet ski ready for the water.

i'll probably put new seals in it and clean out the cases but i dont think i'll get the crank rebuilt. i was talking to my dads friend who owned the sled before me and he said the crank was rebuilt about 1000 miles before i got it. and ive put about 3700 miles on it in the last 2 years, so a crank with only 4700 miles on it should be fine. my dads old 98 ZR600 has over 14k miles on it with the original crank. and his 95 ZR580 has gone 10k miles on that crank so im not too worried about the bearings unless there is bottom end damage from the locating pin or part of the piston.
 

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ilive4snow700 said:
woodford vermont had good snow. we trailered to twin brooks ( http://maps.google.com/maps?hl=en&um=1&ie=UTF-8&q=twin+brooks+woodford+vt&fb=1&gl=us&hq=twin+brooks&hnear=woodford+vt&cid=0,0,2428902489312980325&ei=TbGzS4ewA4GKlwfwhrC7BA&sa=X&oi=local_result&ct=image&resnum=1&ved=0CAcQnwIwAA ) and rode on trail 7 most of the day. feeder trails and low elevations were pretty muddy, but high in the mountains on the national forest roads there was 2-4 feet still and groomers had been out every night. ....but that was on sunday. after the rain they had the past few days its pretty much done, unless you can find a way to get to the high elevations, and even then there wont be much riding left.
As of Wednesday you could still ride 7, but you had to park at Summerset/Kelly Stand, sure it's done now though. Why park at Twin Crooks go across the road to A-Z snowmobiles, free parking in back, and onle less road to cross! Look me up next season we ride Woodford Every Saturday, and usually 1 or 2 nights during the week!
 

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Discussion Starter · #17 ·
it was free parking at twin brooks since they were closed, plus that just where my dad decided to park.
we usually dont ride woodford, we are usually in hardwick and north of that. we were just bringing the sleds back home to go in storage and decided to take a little detour to woodford to ride since there was still snow.
 

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Discussion Starter · #18 ·
update- more broken parts!

well i was taking a closer look at my sled and was trying to figure out why the engine was moving about 1/4 inch back and forth when i pulled the starter.
apparently the right rear motor mount, the aluminum bracket not the rubber mount, was broken clean in half. there is about a 1/4 inch gap between the half bolted to the motor and the half mounted to the chassis.

the shear torque of this motor has broken a ZR1 chassis before (the most rigid ZR chassis ever built IMO) between the bulkhead and tunnel. and now torque of the 700 has claimed a motor mount.
 

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Discussion Starter · #20 ·
im probably gonna have it welded back together and beef it up with some aluminum plate welded to each side of the mount.
 
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