pics of exploded piston on my 96 xp

[tshaw]

Well after pulling everything apart here are a few pics. Rave valves had good clearence cylinder doenst have any burs or anything that might have caused it. Any other ideas what couldve went wrong. I had it apart for base gaskets installed everything but air filter started and ran after installing air filter it was harder to start so added little gas in cylinders and cranked for a few till this happened

 

[CReynoldsMIZ]

im wondering if you could have dropped something in the cylinder that caused it to hit something and break the crown. Did you check the squish gap as well? Im wondering if you could have not had enough clearence and it hit the head. Do you have any pics of the head dome?

 

[tshaw]

Theres one mark on the head but id guess its from a piece of the ring. I didnt measure the squish like I should of guess a rookie mistake. I used the same size base gasket .6 and with the new o-rings and cleaning off piston top and head I shouldve had extra clearence. I will be worried now because im sure now theres going to be a piece of piston/ring that is just sitting in the bottom end

 

[CReynoldsMIZ]

Im going to guess a ring caught and messed this thing up, im sure you know at this point you will have to disassemble the whole engine to get all of that broken stuff out of the lower end. At this point, unfortunately it might be cheaper/easier to get an SBT unless you know you can tackle this job...

 

[tshaw]

also creynolds its way off subject but how do you like ur js550. Ive got one same year picked it up for $300 starts and runs fine was to cold to water test im worried its a ticking time bomb compression is 180 stock head so im sure its milled to the max.

 

[tshaw]

Im not sure what I want to do yet with it. If I take it apart I feel like it should just get rebuild then id just spend the extra 3-500 to have the warrenty. That would be the best thing I could do I know cheapest route would be throw a piston and rings in take my chances and always make sure Ive got my tow rope lol

 

[Dacapster]

Like said before....did you donk thay part of the piston installing it?.....Right to the ring gap it does look it stuck there.

 

[CReynoldsMIZ]

Honestly, I think the JS550 is about the most bulletproof ski ever made. Not super fast, it wasnt oil injected, just a good solid ski. The ski, well actually all of the standups on my avatar are actually my dads (I just list them because I do the maintainence :thumbsup. He bought the js440 in 1982 i think, the js550 in 86, think he probably bought the js300 in about 93. The 300 he rode once, then never again, and the 79 probably hasnt been ran in 20 years).He has literally never done any engine maintainence on the JS550, I mean spark plugs and greasing, but I mean the carb has never been off, which i find to be a miracle and a testament to the quality, and the damn thing just runs perfect. I was born in 89, and with my 3 sisters born after me he didnt really have time to ride until about now. The 550 probably sat a solid 10 years in our basement with nothing but the gas drained, and we started it up a few years ago and it fired and it rides like new. That being said, we did have some problems because we clogged a cooling line with sand, so a flush kit would be a good idea, but nothing that wasnt fixed fairly inexpensively. The ski still has perfect compression, i think it was about 135 stock, so yeah, 180 is REALLY high.

I have some buddies around me who are some huge standup freaks, and although they like our JS550 because it is extremely clean, stock, and untouched, they arent really fans of it. Most of the standup guys will go out and get Yami Superjets, they got bigger engines and bigger pumps and are easy to mod and have a better hull. But for just recreation, the JS550 is perfect.

It also kinda depends on your size, i am about 5'10"-5'11" and about 215-220 lbs (workin on the latter number, cant do anything about the former lol). I personally dont enjoy riding the standups, I guess I just never grew up with that the only option like my old man, plus I think being a little bigger kinda effects the riding. Ill ride around on it about 20 mins and then im ready to get back on the GSX lol, it is actually really a workout if your new at it, and the whole leaning to steer really throws me off

Here are a few pics of it...

 

[racerxxx]

When you put the gas in the cylinder, was it a lot? I'm just wondering if it would have been possible that the gas collected in the ring land and when the ignition fired off it basically detonated and blew the ring land off the crown of the piston. But with the fogging oil not enough ignition to actually start the engine. I've heard of bombardier pistons getting a hot spot where the indexing pin is and causing detonation and wasting a piston that way, but the top ring indexes roughly 90 degrees from where your's blew. The hot spot detonation also is not on start up, but after running a while.

Were you trying to run it on the hose? or were you just trying to fire it up?

Another question I have is what did you use to clean the crowns of the pistons with and the mating surfaces of the cylinders and the cases?

 

[tshaw]

Dcapster im not sure what your saying. The rings were lined up with the pins in order to compress.
creynolds thanks for the info im only 5 6ish and SHOULD be around 165 around spring time lol. Any more pics of trailer thats what im doing with my double shorelander.
racerxxx it was very little on the gas premixed also. I know there was a decent amount of fogging oil that was sprayed previously. Im just not a believer is starting fluid ive seen people do it and it seems to work but I dont use it. Was just going to start it in garage for a few seconds so there was no hose. Any cleaning I do is with brake cleaner and I forget the name of it but just a little brissle looking thing that goes on a drill at slow speed. Its whats used when cleaning alum oil pans on cars when theres no gaskets just sealent.

 

[CReynoldsMIZ]

Yup...here is a few more pics...

Please, no comments on the messed up paint on the front, my dad cusses his ol buddies name when back in the 80's they bumped something and chipped the paint lol

 

[racerxxx]

I assumed that it was a wire brush attachment on a drill or a 3M cookie cutter pad on a die grinder. Why I asked is it's POSSIBLE, that's possibly a strand or something got caught and wedged causing the ring to pop? Just a wild guess,not what I would ever imagine but you never know.

You could always put it back together and check the squish, you'd be in the ballpark at least.

 

[Dacapster]

If the pistion did not get banged up when working with itt hen it must have been a stuck ring. 180 apart is standard for the gaps. Sometimes wierd stuff happens.

 

[Dr Honda]

That's purely mechanical damage. I'd say a ring caught... and busted the piston. (since your RAVEs are OK)

 

[mikidymac]

The part that broke is on the intake side. As Dr. said you more than likely installed the ring not exactly lined up with the alignment pin and the ring got snaged on the transfer ports. Given that this is a used cylinder, ring and piston combo you have a little more clearance and the rings will go into the cylinder not exactly aligned with the pin. I have seen it done and have done it myself as they can spin out of alignment when sliding the cylinder on. I always insert the piston and rings into the cylinder slowly and one at a time then look to verify the ring did not spin on the piston and out of alignemnt with the pin. This is very esy to do when reasymbling a used engine.

You should split the cases, install new gaskets and seals, check the clyinder port chamfer in the area of breakage get a new piston for that cylinder and a new set of rings for both. That is the cheap fix.

 

[tshaw]

Racer this is what I was trying to describe that I used to clean lol. I think im going to just send it away. To do it right id have id say $300 into it with more time that I dont have and who knows what else could go wrong or what else I can screw up in the process. I like the idea of having a warrenty for 2 years just looking for a trouble free summer out of it and fresh rebuild. Good mpem spare rectifier, key, dess post, rear ebox, front box, new wear ring, fuel lines, selector, clean carbs I should be ok for whole summer. Ive already spoke to ses it seems cheapest and heard good and bad things about ses, fullbore, and sbt so ill stick with cheapest and 2 year warrenty.

Thanks for all the help

 

[SabrToothSqrl]

After a summer of three engines. Yes, THREE. I used a shop. No fault = best money spent. Of course I'm on year 2 of my no fault. But I don't think I will have any issues.