It Finally Happened!

[rev500]

While riding today my amost 10 year old Skidoo 500 Grand Tour Sport apparently melted a piston. It was just shy if hitting 10K miles. This has been a great machine. Nothing has ever gone wrong with it until now. It sure does not owe me anything.

I will be tearing the top end off tomorrow to see how bad it is. My question is, how do you get the cylinders off if the Piston is stuck in the Cylinder? I have changed two pistons on my other machine but they were not siezed. Any suggestsions?

Also, based on the sounds that it made when it happened, and the looks of the top of the pistion when looking through the spark plug hole, there is a good chance that debris made its way into the crank case. I may need to pull the crank as well. Taking it out and putting it back in I think I can handle but I think I want to have the crank rebuilt by someone who knows what they are doing? Can you recommend anypne (I live in The Ann Arbor Michgan area)? How much does it typically cost to have a crank reworked?

Any help/advice would be great and appreciated as I start this project.

 

[ezra]

new looks cheep http://www.skidoopartshouse.com/oemparts/a/ski/500c2858f87002314436e7a2/crankshaft-and-pistons
if that is correct I would go that rout.
I have spent close to a grand a few times getting a crank rebuilt trued welded and pinned
but would prob be 5/8 less for just a standard re build.
try hot rods they may have a exchange
I would pay no more than 375 to have yours rebuilt

 

[rev500]

Thanks ezra. I think new would be the way to go. I will find out tomorrow when I try to pull the top end off. Hopefully the piston is not welded to the cylinder.

Another thing on these engines, it looks like you cannot replace the cylinder sleeves. You have to buy the cylinder block and sleeves as an assembly which looks like it will run 600 dollars. Depending on how much damage is done, I may need to determine if the machine is worth fixing. I think a 10 year old sled with 10K miles may only be worth 1500 or so.

 

[ezra]

why do u think u need new jugs?
re plate is prob the most u will need.
http://www.mt-llc.com/cylinder.php
I have done many top ends very very few have needed crank work and prob 3/4 need to be re plated

 

[whitedust]

If the rest of the sled is in good condition maybe an engine exchange is way to go but you only do that if sled is a keeper.

 

[rev500]

Thanks for the information. I was not aware that there was a replate options. That would be great. Later today I will know the damage. How bad can the cylinder sleeve be gouged an still use the replate option?

I hope the the bottom end is OK. I have done two top end rebuilds on the other sled due to the ring spinning (same sled style) and it has been fine.

The sled is a keeper for sure. I bought them new when we got back into sledding after my son stopped travel hockey. They have been trailer stored and have never even sat out overnight. We have not beat them up due to the fact that they need to last until College costs are gone. If the sleds quit, our riding quits . Cannot afford getting new sleds now. The chassis is in great shape.

With respect to the Piston, is it safe to use a piece of wood to punch it out if it is stuck? I do does not look like the piston is at dead bottom center so the crank should have room to turn?

 

[ffemt]

Also if there's a little alum. on jug that can be acid washed off

 

[whitedust]

Since keepers I would go with engine exchange & get warranty as well. This way you know engine is good & not going to nickle & dime you every year enginewise. Good exchange programs out there ask your dealer if BRP can help?

 

[sw_lower]

Sea-Doo Clinic ,, cylinder and crankshaft exchange.. Mark Hildebrand 298 s. Fremont Rd, Coldwater,MI 517-238-5955 www.outboardjunkyard.com They have a ad in the Michigan Auto & RV Book ,.. the free one.

 

[snowfreak56]

When you get it apart and find out what ya need get ahold of Matt at MCB he can fix you up at a reasonable price and you may be close enough to him to save ya some cash on shiping.You will not be sorry you called him.

 

[rev500]

WOW! It is NOT Good - Need Advice from the Experienced Two Stroke Mechanics!!

We'll, I have pulled the top end and it is not good at all. I can script what happened
1. Ring Spin's on Piston
2. Ring smashes into Power Valve
3. Collision of said two devices in number 2 break off a piece of the Piston
4. On the up stroke the piece of the piston has NO place to go and slams into the head
5. Piston stop but crank keeps going
6. Piston Explodes
7. Piece go everywhere
8. Piston arm comes loose and starts beating the crap out of everything it can reach, most notably the cylinder sleeve
9. Results are mayhem, plane and simple.

Here are the pictures. I will have to pull crank because there is clearly debris down there and as you will see in the pictures below that piston arm is bent. Please take a look. Any advice is welcome. Not sure if rebuilding is best or if another whole engine is the better plan. I am a fair mechanic and am willing to take on the bottom end rebuild but a little guidance from those that have experience with this would be great.

Here is the Head:

Here is the Piston In The Cylinder:

Here is Looking at Where the Piston SHOULD be after removing the Cylinders (UGH!):

Here is the Bottom of the Piston Still in the Cylinder:

Here is a Picture that Shows what Happened to the Cylinder Sleeve:

 

[reiley99]

that's why I replace my piston every 3k miles look into spi pistons there cheap but very good. but use oem gasket kits to keep tolerance correct some after market gaskets are different thickness than oem.

 

[frosty]

Get a rebuild......way to many problems to fix.

 

[ezra]

yeah time to start shopping for a good used motor.
U will deff not get full core charge back on a rebuilt but U may get some back.
tough deal on that one few other options start looking in to wrecks to bid on cranky ape crashed toys etc etc you may find a totaled 500 or 600 or something with all the parts u need.
if rest of sled is clean parting out usually brings more than if u sold outright PITA but a option.

 

[rev500]

Thanks. I was already there in my thinking but I wanted to hear it from some others that know more about this. I have already sent emails to a couple places inquiring about a rebuild including MCB. I assume that I can put a 600 in the same as a 500? The sled is worth saving as long as I can keep the cost to around 2000. Below are some pictures of the sled.

 

[nitro699]

ben in your shoes several times over the past 38 years, find a different motor, or cut your losses & run.

 

[rev500]

Well, my plan is to pull the engine and finish taking it apart. See what the crank looks. This will not be done in a rush as the money to repair is not there. Probably will become a summer project and I will look for used parts over the winter or come across a good deal on a used/rebuilt motor.

 

[ezra]

dont wast your time crank is junk with that rod twisted like that I can almost guarentee no parts worth saving.
start shopping U may find a decent used to get u back rolling and if u find a Ebay thing U can always charge it on pay pal and pay this summer and not miss a season