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HELP PLEASE!!!!!! 2000 Seadoo GTX RFI Millennium Edition

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Was hoping I was wrong :(

You got 200 hours out of it, not too uncommon to start seeing these kinds of failures at that point. The majority of my 2 stroke engine failures happened around 200 hours.

See if Nick Cairns has a motor for you.
Sadly I only got under 10 hours myself. I bought them used didn't get to put much time in at the lake. [emoji53]
 
I've had three machines (an old Polaris 780, Polaris Virage 700, and a junk 96 GTi I bought for parts) that had pistons that looked just like that. On all three, there was at least one bad crank bearing. The bearing starts to come apart and tiny pieces get pushed into the cylinder with the air/fuel/oil mixture and get thrown around, beating the crap out of the piston and head. The fact that the majority of the damage is occurring on the outer edge of the piston somewhat confirms this. Usually, a piston running lean develops a crater and eventually a hole usually somewhere in the middle.

If it were my ski, I would pull the engine and remove the top end on the bench, then carefully inspect the cases for bearing material and the bearings. I would go ahead and split the case and get the crank out to look at it closer.

You may be fine and it may not be the crank, but the many scenarios I've seen online with that type of damage and what I've seen with my own personal skis supports my theory.
 
Look at the piston wash it is lean


What wash :o

Yeah way too lean.piston wash.gif

Here's a better wash patern:

20140724_211418.jpg



As for what and how and why.

Likely the injectors are just getting old an clogging up. People normally replace them every so often just to avoid this happening.

It was probably working great with no sign's of a problem. But there was a point where this engine was not getting enough fuel and that in turn heated up the top of the piston to the point where the outer edge got too hot. Over time this overheating caused little chunks to come off bit by bit.

As for why it ran good and then got worse after a while, that is what hapen's when they overheat and score the cylinders or the rings stick in. If the chunks that came off wedged between the head and piston this could squish the ring land and hold the ring in.

Lean running leads to excess heat, heat leads to scoring, scoring reduces compression and so on until either there is too much scoring on the cylinder to give proper compression or there is too little left of the top of the piston to compress that volume. Either way your throwing lots of fuel and oil on a dwindling flame.

For why the wet plugs, You have lots of fuel and oil in there but not enough compression to ignite it all. All that is left in there and splashed onto the plugs.

Those compression numbers do say it all though.


I'd recommend to NOT do the top end while its in there. Take the engine out and do it properly where you can inspect everything.

One reason is because when you pull the cylinders up off the base, the base gasket will rip and you'll find this little water jacket nook where all the sand and crap likes to end up. This will end up in the base and you'll have to remove the engine to disassemble it anyways.

Another is that there may be chunks of anything ( aluminum piston, piston ring, needle bearings) in the base and it does sometime get hammered into the casing.
This stuff sits there until you fire up the engine again and then after a while works loose and bounces around in the top end ruining all your hard work...

Oh and replace the injectors. I've herd they are about 75 each.
Check the fuel pressure as well. Just to be sure.


Didn't someone have a part number for the internal fuel filter inside the fuel pump ?? I can't remember what it was but you can't get that from the dealer.
 
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Great info Mekanix. Especially the running lean. I remember back in the day when I used to tune performance skis the famous line from the customer was, "It ran the best it ever has then just shut off". A ski just on the edge of being too lean will make the most power and a little more lean will make even a little more, that is right until it seizes.
 
Was hoping I was wrong :(

You got 200 hours out of it, not too uncommon to start seeing these kinds of failures at that point. The majority of my 2 stroke engine failures happened around 200 hours.

See if Nick Cairns has a motor for you.
Who is Nick and how do I get a hold of him?
 
Nick is [MENTION=41828]Minnetonka4me[/MENTION]. Wish I could help but he already has all my money :thumbsup:
 
Hi, I am totally new to owning a jet ski and purchased this model today. Great condition and previous owner was a mechanic. Only thing is he has disconnected the oil and now have to premix the oil and fuel. Would I be better getting this put back the way is should be or is it ok. He suggest 20-1 ratio but I have read it is more like 40-1 ratio. Thoughts please
 
I was looking at the picture of your 2 stroke oil filter. My concern is that you may be using the wrong oil. It looked brown to me in the picture. This tells me that you are using Sea-Doo XP2 oil. That oil is mineral oil. As far as I know all RFI models require Sea-Doo XPS oil. That is a synthetic oil. The XPS oil is red and is around $45-$50 per gallon. The previous owner of both of my skis (2002 GTX RFI and 2003 GTI RFI) used the XP2 and caused all kind of problems. This included full engine rebuilds with new crankshafts. You should also have your Throttle Position Sensor calibrated to true zero. This requires a Sea-Doo computer from a dealer if you can find a dealer that will still work on two strokes. No dealers in my area would touch my skis. I purchased the CAN-DOO pro diagnostic tool and now I can pretty much do anything myself. The CAN-DOO pro is around $400.
 
I was looking at the picture of your 2 stroke oil filter. My concern is that you may be using the wrong oil. It looked brown to me in the picture. This tells me that you are using Sea-Doo XP2 oil. That oil is mineral oil. As far as I know all RFI models require Sea-Doo XPS oil. That is a synthetic oil. The XPS oil is red and is around $45-$50 per gallon. The previous owner of both of my skis (2002 GTX RFI and 2003 GTI RFI) used the XP2 and caused all kind of problems. This included full engine rebuilds with new crankshafts. You should also have your Throttle Position Sensor calibrated to true zero. This requires a Sea-Doo computer from a dealer if you can find a dealer that will still work on two strokes. No dealers in my area would touch my skis. I purchased the CAN-DOO pro diagnostic tool and now I can pretty much do anything myself. The CAN-DOO pro is around $400.

Nice observation but this isn't always true. It was only a few years ago that the XPS full synthetic became red. Seadoo changed suppliers so the older XPS full synthetic was golden brown too just like the Semi synthetic and mineral oil.

Bottom line though is if you don't know what is in the ski flush and replace with the correct oil.
 
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