Hey guys I am a newb to Polaris ATVs. I recently picked up a 97 Scrambler 400 for $275. The top end still had its original piston, but its blown. When I removed the cylinder the skirt on the intake side was broken off. There is a large chunk of metal missing somewhere and I don't see it in the crank, exhaust, or anywhere else. I sent the cylinder out to be bored, honed, chamfered and want to make sure there is no more metal in there. Anyone run into this problem before?

 

That is common on 2 strokes. The metal probably went out the exhaust in small peaces. If the lower end is clean it should be fine just put the new top end on it and ride.

 

I did find very fine shavings in the reeds and exhaust port going out of the head. I dumped oil in the crank spun it a couple times and then dumped the oil out. I repeated this around 10 times and I can't see anything in there and the bearings/crank are nice and tight and spin smoothly. So should I be safe to install the top end and put this ATV back together, or should I be looking in more places for metal to be hiding?

 

get a good magnet, one that extends out, put it down in the cases carefully kinda fish around and see if it brings anything up, if engine is removed turn it upside down and rotate bottom end , see if anything comes out if you dont find anymore I guess put it together and run it

 

Thats what I did, first I used a magnet but didn't get anything. Then I removed the motor and dumped it upside down after running some 10w30 through it.

 

I would seriously think about disassembling the entire motor. i've seen several of thos motors over the years that had broken pistons in them. Every one of them I have torn down with broken skirts had cracks in various places-crankcase area, between the oil pump area and crank area, etc. It would suck to reasemble it now and then have to tear it back out an all the way down again.

 

Found the pieces! They are all stuck in the muffler.

 

How do you get the broken pieces ot of the exaust pipe?

i have a 97 exprees 400 i got last year and it too had a busted piston skirt . I rebuilt motor last winter and got it to start ,but i still wouldint idle or run good unless i had exhaust pipe off. this made me think it if pluged. It runs great with just header pipe on ,but chokes out with exhaust on. I also wonder if maybe some critter or muddobers pluged it up with a nest. When i got the express it was left outdoors with the broke down motor for over 2.5 years. How can i free up? or clear the exhaust?

 

we used to pour gas in our old 2 stroke mufflers and light them on fire , it would burn all the carbon out, after thefire went out you could bump them on the ground and all the carbon would fall out

 

Magnets don't work on aluminum. LOL
Good idea tho if you drop a cir clip down in there.