New Piston and Rings?

[foxloat]

I have a stock 98 superjet that I bought a few years ago, I've probably put close to 300 hours on it, i'm not sure how many hours were on it when I bought it. It doesn't look like the motor has ever been opened up. The ski run fines, but haven't done a compression test. So my question is that is it worth it to put a new set of piston and rings in? Or just run it until something breaks?

 

[Wizards Powersports]

Run till she gives up the ghost...then you have a good excuse to build it up and get the cylinders ported, and start upgrading

 

[Quinc]

Do a compression check. If it is low you can take the cylinders off and check the ring gap. See the manual for specs.

 

[foxloat]

If it's low i'm just going to put new pistons and rings in

But if i did get a stuck piston could that wreck the crankshaft or something else besides the cylinders? I'm not a mechanic and don't know a lot about motors, but I can do a 2 stroke top end.

 

[Quinc]

If it's low i'm just going to put new pistons and rings in

But if i did get a stuck piston could that wreck the crankshaft or something else besides the cylinders? I'm not a mechanic and don't know a lot about motors, but I can do a 2 stroke top end.

It might be fine for another 300 hours. It might blow on your next ride, ruin the crank and put holes in your cases. Nothing wrong with some preventive maintenance.

 

[foxloat]

I think I will put new pistons and rings in, port the cylinders and put a girdle on over the winter, now that i'm out of college and making money. is there a way to check to see if the crank is in good working shape? like is there suppose to be a certain amount of play? Or anything else I should look at while I have the cylinders off?

 

[Ducky]

This is what my pistons look like in my 61x superjet motor. My ski is still super snappy, and I have a few people say my ski pulls harder than there 760/781 motor. Lol...going to run it until it blows up...it owes me nothing. I say...keep running it and build a better motor on the side...no down time.

 

[kswiatk]

If i were you I would replace the pistons,crank and all internals. Nothing sucks worse than rebuilding it during the season when you could be riding!
My preventative maintenance last year found a collapsed piston skirt, which could've destroyed everything if i had kept riding, but i managed to get lucky and find it.

 

[Quinc]

I think I will put new pistons and rings in, port the cylinders and put a girdle on over the winter, now that i'm out of college and making money. is there a way to check to see if the crank is in good working shape? like is there suppose to be a certain amount of play? Or anything else I should look at while I have the cylinders off?

Read all of the threads in the FAQ. I think there is only two pages worth. One of the threads also has the download link for the superjet manual. It will tell you how to check the crank etc.

 

[foxloat]

That's pretty crazy that your pistons look like that and your ski runs that good! I have no idea how to put a new crank in. but I'll check the superjet manual and see what it says before i put any money into the motor.

 

[Quinc]

Go through the faq. Tons of info and a thread with picture picture instructions on how to remove and install a crank:
http://www.x-h2o.com/index.php?forums/tech-faq.26/

 

[foxloat]

Cool lots of helpful info I didn't know about thanks!

 

[kswiatk]

That's pretty crazy that your pistons look like that and your ski runs that good! I have no idea how to put a new crank in. but I'll check the superjet manual and see what it says before i put any money into the motor.

I have really good luck with SBT rebuilt cranks, and its only $200 too. However, SBT cranks are less likely to last as long as oems.
Putting a new crank in is easier than doing a top end IMO, i suck with circlips.
Check the manual or find some videos on youtube. You just pull the cases apart, Change the seals and crank then reseal the flange with 1211, basically.

 

[Harbor]

I'd skip SBT crank and have your original OE rebuilt

 

[Sparkplug]

It's all about spec. If your parts are in spec, why would you replace them? Is a new part different spec? NO. It's the same spec. Your wasting money buying new. It will have the same tolerances. Metal may fatigue, but visual inspections are plenty to assure it's not gonna grenade out of nowhere. Only replace what is needed. Dowload the factory service manual and see for yourself.

I'm not surprised at all that engine is still running. I've seen worse.