BOOBOO Posted December 15, 2004 I have a 03 450 and plan on racing it in 05. The bike is a beast! Is there any need in replacing piston and rings? I bought the bike from a guy that probably never twisted the gas past half throttle and it has only been rode hard since I got it.(about 2 months) Share this post Link to post Share on other sites
mkporn Posted December 15, 2004 Depends how much you ride, how hard and how often you change the oil.... I replace mine once a season. Have owned a YZ 400-450 since 98. Share this post Link to post Share on other sites
Wayne_Thompson Posted December 15, 2004 Depends upon how much you ride and how hard. I replace mine once a year. It is cheap insurance. Share this post Link to post Share on other sites
yz426onNOS Posted December 15, 2004 when you start to notice a power loss. Share this post Link to post Share on other sites
crazyYammi Posted December 15, 2004 If you really want to know you need to take it apart and check the end gap on the rings. Share this post Link to post Share on other sites
smokin529 Posted December 16, 2004 I've been racing YZF's since '98 in the woods and moto and only do a top-end once a season. I change my oil and keep a clean air filter in it all the time. Share this post Link to post Share on other sites
jimmyg Posted December 16, 2004 you want to change the cam chain once a season at least from the motors weve taken apart it seems like a high wear item . Share this post Link to post Share on other sites
BC3 Posted December 16, 2004 I probably won't do it but they say top end freshen -up every 50 hours....That would be a new piston and rings... BC Share this post Link to post Share on other sites
mxchase Posted December 16, 2004 I learned from past experiance that it is cheaper to rebuild it every so often. Don't let it go too long. Share this post Link to post Share on other sites
yz007f Posted December 17, 2004 I put in a new piston and rings every season plus get my vavles re-cut. Mine comes apart so much I have to buy new head bolts! lol. I change my oil after every ride, It all makes a difference, You can leave it but the piston and rings dont cost that much. At The same time change the wrist pin and make sure you torque the head down right (with get gaskets of course). Also stay away from aftermarket products. OEM is far the best! Share this post Link to post Share on other sites
yamaboy23 Posted December 17, 2004 Dam im confused here....i thought we were talking about 4-stroke dirtbikes rebuilding them that often is insane with that 2-stroke mentality i should be rebuilding the motor in my truck once a year to be on the safe side .....RIGHT Share this post Link to post Share on other sites
oldblue Posted December 17, 2004 With motivation stemming from TimFurryBalls and this thread I just ordered up a Wiseco top end, Cometic gasket set and timing chain. 2 years of working my baby hard and now it's time to give a little love back. My goals over the next two weeks (or whenever the parts arrive) in no particular order: New tires (done), new piston & rings, new wheel bearings (done), new timing chain, grease linkage and steering stem, new brake fluid and check valve clearance. Did I miss anything 😢 ? Share this post Link to post Share on other sites
