Hello all, first i must say thanks for all the help and advise everyone has given me last year on the problems i was having with sled...Thanks!
now i have been thinking for this year if i should rebuild top end or just leave it.
the sled is a 2000 arctic cat zl550 with about 6500 miles on it. still runs good and compression is about 120 each side. i have spoken to a few and say "just leave it those engines are tanks" and some say " if your looking for trouble very soon its worth the change" ......so this is my dilemma!!!
i have no clue if the sled has been rebuilt or not so that doesnt help either. i have been looking at different types of pistons and have come across either oem, wiseco ,kimpex or spi. i have heard that the forged is best like wiseco but i will have to get cylinders honed, more work in period and must warm up 10-15 minutes ? havent heard much about the spi's or kimpex as they are cast and a bit weaker? but more reliable and no work in period or warm up. please any suggestions would help me out here, planning to do this in the next few weeks if i do.
also does anyone know where the drain is for coolant on this engine so i dont flood crankcase again from removing the heads?
# 10 to drain coolant http://www.brownsleisureworld.com/Pa...s/0733-047.png
If it’s not broken, don’t fix it!?
I’ve seen 1.5-2 x your mileage on some snowmobiles.
Take exhaust manifold off, lock at the piston.
Lock for scratches on the piston.
Also pay attention to the area close to top piston ring. If you see almost white/polished aluminium above the top ring.
-if so, it means the piston is to worn and is tipping over in the cylinder.
Replace piston’s and be sure to measure wear in cylinder bore.
...I have also seen some breakdown at a 1/20 of your mileage.
90% of them breaks/melts from fuel starvation or not being warmed up properly.
9% is a result of not being summer conserved, = clogged jets (fuel starvation again) and/or rusted bearings
The last 1% is due to Mr. Murphy
Oem. Pistons seems to be more reliable than aftermarket ones
Oem. Piston price is the down side.
Wiseco is very good, down side is they “rattle” a little directly at start and do need a good warm up, surrounding temperature makes its impact on warm-up time.
….just my 5c
Where I sled: Around town and Christopher / Emma Lakes
The drain is on the front of the waterpump housing. There is a nipple where you can attach some tubing to direct the coolant into a pail. Wiseco pistons are not any better than OEM, and if you're not building a racing engine, then there is no need to move to a forged piston. I've always heard good things about SPI pistons, but you can't go wrong with OEM. The greatest concern with high miles becomes skirt fatigue, not ring seal, which still seems good by your compression readings. This means you want to replace pistons, not just re-ring, as some would say. All engines require a proper warm-up period, no matter what pistons are installed and every time you install new pistons and rings you must re-surface the cylinders, which means putting a fresh crosshatch on the cylinder walls. Wiseco will probably tell you that their pistons should be properly sized for the stock bore, however you would want to measure clearances and if machining is required, the cylinders would have to be re-plated after the bore is modified.
I would be temped to leave it alone, unless you really want to spend some money and do some work. It is going to break eventually, so do whatever makes you most comfortable. I'd use OEM, or SPI pistons.