Finally apart

[Vumad]

I finally got my engine apart. Here's the pics.

The brief story... I was riding my ski. It was running strong. I rode into shore and hit the stop button. It wouldn't start again. It had some compression (I can feel it with my hand) but not enough to fire the ski. My pressure gague said my cylinders were 30 and 50 afterwards (but I have no starting compression to reference).

Here's pics of the pistons, head, and reeds. I found it interesting that based on the way the head gaskets, it looks as if water flow would have been restricted through the block. It appears water would have only been able to flow though the head, unless water went in through the exhaust and the head... but how did it get back out? I'm not sure I understand how it worked, but it looks like the channels were blocked by the head gasket material (not corrosion at all).

I don't know much about engines yet, but it's obvious that the front piston is shot and the domes are pretty messed up. I think I'll just take everything I have between the two engines and just rebuild one almost new engine. My pump sounds like it's having issues, so if I can get that sorted out, I'll just redo everything and have a nice reliable ski.

Any info would be great. What's wrong (outside the obvious), what caused this, how I should go about getting my ski running (w/o saying, go buy a super jet) and what the costs might be.

Thanks.

PS. Yes, I know I made a big deal about getting this thing apart when all this happened, and yes I realize it's been a week and a half. I had to put school first. I just poured a bunch of oil into the instake and cylinders and cranked it over to move it arround. I would have done the work earlier but school comes first. I did get a 90 on my test! I started clinicals too. I did CPR on a guy who was dead but isn't dead anymore. :bigeyes2:

 

[Vumad]

On the topic of advice while rebuilding this engine...

I do have a PJS head pipe, pipe and head that I will probably use if I rebuild the engine. The PJS head appears to have the same kind of damage as this head.

I realize I have a half dozen threads about this stuff. If I knew what I was doing, I wouldn't talk about it so much, I'm just trying to get info.

The 3rd pic is the PJS head. It's pretty messed up. It was like that when I got it a few weeks ago. I'm not positive if it's salvagable, if the domes can be shaved or anything.

 

[vitaly]

From the first look it seems like water is what caused the damage.

 

[Vumad]

From the first look it seems like water is what caused the damage.

I have a stock waterbox and stock pipe. Could water have got back in through the exhaust? I think I had a cooling leak now that you mention it.

There's actually a cooling line going to the pipe, the pipe is hollow and there's nothing that would keep the water from there backing into the exhaust.

Just talking outloud.

I thought something might of gotten into the cylinder and damaged the piston and head. I realize now that the dome is melted to the piston.

 

[TB]

looks like my old 650 when it grenaded..the damage on my head like that was actually pieces of my rings..when i took the pistons out i found out it was actually the crank went to chit and sent the top end with it at wot. when i took the cylinder off i found pieces of my pistons everywhere in the crank case..actually blew the skirts right off the pistons:bigeyes:

 

[tom21]

um you need to come by the shop and I can use my ski as a reference and school you in what little knowledge I have.

at first glance I would suggest looking for a blocked cooling line, or improper routing. unless you had enough water to fill the ski to where it got in the carb, where you subbin alot? ski run on its side for minute? you have aftermarket flame arrestor on there right?

must be that time or year, my motor is junk as of last friday.:bananapowerslide:

 

[Vumad]

Tom, are you at the shop today? It's 10 am now and I don't need to leave for my clinical until 2.

I run my bilge during every sub. Much subs are novice so I take on a good amount of water but not too much. I always make sure I run it empty before I try the next sub.

When I was flushing the ski (It wouldn't run but fresh water > salt water) I could hear water in the front cylinder, so I'm going to go with a cooling leak.

I was doing the same as normal. I highly doubt water got in the carb. Yes, aftermarket flame arrester. I'm going to go with a cooling leak.

I'm not quite sure what to do next. It's apparent I need at least one piston, probably 2. I need to get the head cleaned up. I think the PJS head is a high compression head I could use instead. How high of compression can I get on pump fuel? How much more power can be expected over 150 PSI?

I'd kind of like to tear the entire engine apart and replace anything that is going to break soon. I think it's been 4 years or more since the engine was maintained (I was told when I bought it that it had a fresh top end 3 years prior). If I'm already replacing the pistons, working on the head and getting a fresh bore, I'd image it would be too much more to check out the crank and clean the thing up.

 

[WFO Speedracer]

Someone like Group K or rossier eng can rework those heads.Basically the take a slice off the head and recut the domes back to specs.I used rossier I think he charged about $75.00 to redo one.Of course you can always pick up a used head cheaper.

 

[dbrutherford]

You better just plan on a complete rebuild... I have done it myself but you really don't want to trust a 10-15+ year old crankshaft do you? You will know more once you pull the bottom end apart.

I would say just get an SBT engine but... that is another story. Keep an eye out for a 750 engine. You can drop one of those right into your hull. I did that to my 650 SX but I must say, it didn't run that much better to justify doing it all out like I did. I had porting, pipe, jetinetics, aftermarket everything. Then I seized it up twice in a row = $$$$

But since you will probably need a 100% complete rebuild, I would rather rebuild a 750 than a 650 just for the more displacement.

Otherwise keep an eye out for a ski just setting around the guy wants to get rid of. You could snag a whole 650 of some type, they all had the same engines. Tandem Sport, TS, Sport Cruiser, SC, X2 650 SX, and the Jet Mate. Just drop in that engine and go. I bought an X2 a year ago and the engine sold for like $450 on ebay! I just wanted the pipe, prop, carb, intake grate, and head that was on the ski. I made out in the end after parting it out.

DBR

 

[Vumad]

I don't want to buy a used engine. I'll just end up in the same spot I am right now. The idea of rebuilding the engine would be that everything is new.