Not really a seizure, but...

[Doofly]

I finally got my two skis out on the water last weekend after a total rebuild of the carbs and addition of the wave eaters. Thanks to the OsideBill thread for the 1200 and a Riva forum for the 800 carb settings...great information. After testing, both rigs felt fine...maybe a hair bit on the rich side, but I'm ok with that for right now. All the plugs look really good.

Well, the GP800R took a dump after about an hour of riding moderate/hard. Riding fine in mid chop in the bay when all of a sudden I lost power. It just wanted to die...no clunks or anything. Starter didn't want to turn the engine at all.

Got it home...removed plugs and it still didn't want to rotate by hand. I started removing all sorts of things...parts that have been removed so far:

• Jet Pump Unit - at one point, I thought the impeller was jammed...not the case, but still off the ski atm.
• Most of the exhaust except the manifold...I was getting ready to remove the manifold when I thought to pull the intake first.
• Entire intake system
• Head

So what I found is that I can spin the motor by hand, but unfortunately it will only spin with ease in the reverse direction. Going in the drive direction, it'll spin up to a point and then lock up. The issue is that this point of lockup changes...after I rotate it a bit in the reverse direction, trying to rotate in the drive direction will cause lockup after approximately one full turn-ish.

I'm not sure where to look next for what's causing the lockup...any ideas?

[nmpeter]

crank bad, broken ring jammed in port or broken rod.

sorry.

pull the head and get a look inside.

if the plugs electrodes are smashed, you broke a ring or a piston and there is debris in the crankcases

[wavedude]

How the cylinders look?? Tops of Pistons look OK? No debri stuck in the tops of the Pistons? Does it spin more than 1 revolution in any direction?

[Doofly]

Well, I believe I have dodged disaster. After posting this, I was reading other posts of questionable seized motors and people recommending turning the motor by hand with a wrench on the shaft (in red). I had all this time been trying to turn by hand on the coupler (in blue)...just because I have always been able to turn the engines in the past without a wrench.


Once I got the wrench on, I had no problem turning it. Stuck the battery on it with oil for the cylinders in hand and let'er rip. Still nothing but a spark noise at the battery. Thought it might have been the starter, but I rechecked the terminals on the battery.

BINGO!!

Apparently my terminals must've come loose in the medium chop because once I cleaned those connections up, the starter spun the engine fine.

Let this be a lesson....check the battery first!!

As for the pistons, they looked fine...actually, looking at the pics a bit more, the rear cylinder power valve seems to be getting corrosion and the piston has more deposits whereas the front looks great.



It was just weird that I couldn't turn the engine by hand before this point. I guess my 1200XLT is what screwed me up because I know I can spin that one by hand without any tool.

Thank you all for reading...I'll definitely be out this weekend!!
Happy Dance!!

[wavedude]

If you can't run it by hand with the plugs removed you got problems.

[MalinTas]

Hmmm a bit left field. But what about checking the starter / bendix as it could be locked in the out position?

[Doofly]

OK...well, definitely problems now. Finally got it all back together...seemed to turn over fine without the plugs in it. Put the plugs in and tried..it seemed to want to start. I thought some of the excess oil I had in the chambers were preventing a clean start, but it didn't seem out of the ordinary. It just didn't want to stay running.

I finally pulled the plugs and did the compression test. Front @ 60-70, Rear at 110-120. Looks like something gave out in #1 now. The motor spins fine with or without the plugs. After doing the compression test, I couldn't get the #1 plug back in. Somehow the threads got jacked. Possibly thinking a warped head maybe.

[wavedude]

Start tearing it down. Remove cylinders and remove Pistons from rods and inspect rods and crank. How many hours on the meter??

[Robfromga]

The piston that you say looks "OK" isn't, its lean.

http://www.snowest.com/forum/attachm...1&d=1228760998

Lean = hot. The fuel mix is cooking on the piston top, you may see a similar coating under the dome also. If that's the one that's low in compression you've got a problem. Your rear piston looks good. Find out why that cylinder leaned out. Broken ring, cracked piston,bottom end issue,carb problem....but you're going to have to tear it down until you find what caused it. Otherwise its just going to repeat itself.

[Doofly]

Thanks for the info guys. I'm in the process of creating a pressure tester for the ski...that's next on the list to make sure I don't have a leak. If no leak, then it obviously was caused by the carbs due to a bad adjustment after their rebuild.