How long should I try to get out of my piston? The 96 Sportsman has 2700 fairly easy miles on it. Had it since new.
But had it to stealer for new seal in the balancer shaft. (I got a manual later should have done that myself, $500) He is trying to talk me into junking it for $500 on trade for a newer one because it likely going to break a piston soon and if a guy is going to do the piston, they should also rebuild the crankshaft and the bike is not worth it. (even though it is in good shape for a 96) I was hoping to pass it down to my sons as a 1st full size bike in a couple years.
I had him redo the seals and it running perfectly 2 years and 200 miles later. But I really don't want to bust the crank case if a piston kit would save it.
Also hard to say but at 2700, likely will need a overbore?

I have done the brakes, rear chain and sprockets, (got 2300 miles out of them so I do look after my stuff) , seat cover, needle and seat, belt, front tires and balancer seals already.

Should I dump it now for something newer while it still runs or would a piston make it last so my three sons can use (likely beat it to death, lol) as they grow up.
I kinda like that it only has 2 cv boots, and is my bike of choice over my 500 sportsman or grizzly when I have to pull a moose out of the bush where there are boot snagging sticks everywhere.
I think it would make a ok bike for the kids when they get to be 10 and have outgrown the 90 and 80 cc bikes.

I could like get $2500 out of it and there is both minty 2006 Yami Bruin and 400 Cat 4x4 with ACT with plow down the road, 500 kms and minty for 4k and 4.3k

Thoughts?

 

Part of what he said make sense! If you have a 16 year old machine that has never been touched I wouldn't just do a top end! If the crank bearings or rod goes out,it will take out a new top end with it. Depending on if you are able to do most of the engine work,letting a machine shop or dealer just install a new rod kit and bore the cylinder it might be worth tying some money into. If you let a shop do it turnkey,you can spend some $$!! Whether you just do the top end only is up to you. Most shops (including mine) could not stand behind a partial rebuild on a old engine.Sounds like you've done quite a bit of repairs and have kept it maintained.You can physically feel if you have any rod or crank play,but it's still a gamble. Saw this a lot at the shop.Some people rebuilt the whole engine,some just a top end and some just sold em and upgraded to a new one. OPT

 

No rule of thumb for how many miles a crank should last? Or the piston?
Guess I'd like to think this motor is only a 1/3 to 1/2 way through its life , but perhaps that is not realistic for a 2 stroke
It runs find and sounds good now so perhaps I should cut it loose as I think it will sell. 4x4 in the 2k range that are not beat are tough to find.

If I did the piston I would do the labour myself but would like still be $250 for piston gaskets and boring. I'd like to think the crank should last for quite a while yet.

Does the rule of of pushing the rod fully down and try to touch the rod against the counter weights work on these engines too?

After reading though the manual on crank rebuilding and installation into the case I'm not sure I'd go that far. I would not feel too comfortable doing that myself or would want to put that much into it.
Ken

 

How you check for any rod bearing play is to have the rod at tdc and gently pull straight up and down on the rod and if you feel even a small amount of up and down movement of the rod on the crank shaft it's time to do a rod kit! Side to side play is ok. Yes it's a pita to do,you have to have a press, truing stand and dial indicator and a big brass hammer if you didn't line the scribed marks up close enough (that you make before you separate the crank shaft) to tap OR beat the crank half to where it's with in .001 max on the dial indicator when spinning on the truing stand. Mainly you just have to have the tools and the time. If you can't feel any slack or movement on the rod it's your call on the top end! OPT

 

I guess the piston skirts really give no warning? No loss of compression or noise just a big crunch/bang all of a sudden?

I guess it would be pretty hard to feel any play in the rod buy turning the engine while still together or to lift the jug up without pulling the piston (so as to not disturb the rings) and check the rod. Guess the base gasket wold likely be torn in this event anyway?
Thanks
Ken

 

Pistons can give you a warning if you listen! If your engine starts sounding like marbles in a tin can then it's usually piston slap. Or if you just notice it just seems like it's making more noise than it used to and compression is getting down close to 100 psi, then might be worth your while to take the top end down. 2-stroke pistons just by their nature of design and how they are lubricated just don't last as long as a 4 stroke piston that is constantly bathed in oil. OPT