piston changes

[gaz1985]

how long does a piston usually last in a yzf 426 and how will i know when it needs changing

thanks

 

[zaneyzrex]

ya got a choice,
1. when it comes apart inside at high rpms
2. ya pull it down once a year and inspect it.
thought i read somewhere a 100hrs but dont quote me on that. if its rode hard change it out once a year and youll be good. its a nickasil cylinder so youll only need new piston/rings/gasket set and a couple hours.

 

[Ol'89r]

2. ya pull it down once a year and inspect it.
thought i read somewhere a 100hrs but dont quote me on that. if its rode hard change it out once a year and youll be good. .

That would depend a lot on how often and how hard you ride the bike. I would not wait a year to check your piston unless you only ride once a month. And even then it would depend on how agressive you ride. Develop your own maintainance schedule. Read the guidelines in the manual and then determine how often and how hard you ride and go from there.

The new four-strokes have a very short skirt on the piston and will begin to rock in the cylinder after a while. If you don't remove them and measure the wear on a regular basis, you are taking a big chance of destroying your engine.

Just my $ .02

 

[wileyE]

Pays to check it, but I remember reading a trip report from a guy who dualsported a 426 and rode the pan american highway and back. How many hours do you think that piston had? He reported it ran good the whole ride. They do use an abbreviated skirt but nowhere near as radical as some of the newer stuff. 426's were pretty solid.

 

[spark250]

I would say it all depends on how hard you ride.
But personally I don't have enough money to do rebuild's every year, a good way I have found is to do a leakdown a couple of times a year.
also, sometimes when these machines need a rebuild they are hard to start and might not like to idle,

dont know if this helps or hurts but that's my 2 cents as well! :)

 

[Spokes574]

I asked this same question about 4 months ago. The feedback from most folks is that they change their piston roughly every 50hrs. Magazines have checked bikes at 70hrs and said that all looks good. I decided to follow most folks on this forum and change the piston or rings every 50-60hrs. I thing the manual will say every 20-25hrs but that is excessive.

Leak check is not always a good indicator. Sometimes wear is at the skirt. When I replace my pistons, I notice less bike vibration and a tad bit more roll on power but not much. The compression seems to be the same 50-60hrs vs. a new piston or rings.

Spokes574

 

[Ol'89r]

also, sometimes when these machines need a rebuild they are hard to start and might not like to idle,

If you wait until they are hard to start you have already cost yourself some money. A leakdown test will tell you the condition of your valves and rings but, it won't tell you if your piston is about to break.

It's best to tear down the engine, measure and inspect the piston on a regular basis until you determine a maintainance schedule for yourself. An hour meter will help keep track of the time on your engine.

Trying to save a few dollars on maintainance can cost you big time in the end.

 

[_JOE_]

Here's a link to a post I had when I tore down my 250f. Your 426 will not wear as quickly, unless you are running it really hard. There's some good pics of how the piston wears and causes rocking or in some cases breakage. That was the original piston and had 60 some hours on it. I'm sure it would have run alot longer, but if you look at the coating on the skirt it is completely worn off on one corner. I would suspect some plating damage to occur before too long runnning that same piston. I didn't notice any loss of power or any change in starting attitude, however it did start to tick a bit at idle. It's always worth the 50 bucks in gaskets and oil to make sure all is well internally...... http://www.dirtrider.net/forums3/showthread.php?t=158258