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My 06 250R has done about 70 hours now. I as thinking of changing the piston. The bike gets a fresh air filter or filter skin every ride and lots of oil changes. To be honest I am only riding 3/4 throttle most of time

Most people seem to do a full top end rebuild, ie piston and valves above 100 hours my valves are fine.

Should I change my piston now?

If it was me I probably wouldnt change it yet if it still runs ok and doesnt have any noticeable piston slap noise, especially if you havent had to do anything with the valves yet. It would be more convenient to be able to change the valves when needed and piston at the same time.

I would put a new piston in ASAP. I think Honda recommends a new piston every 15 hours. I realize most of us, me included, do not do top end overhauls that often, but, you are definitely pushing the manufacturer's design life on your top end. How much is a top end? Now, ask others what they have spent on engine failures.

Def put a new piston in it. I take care of my stuff. Fresh oil more often and air filter cleaned every ride.
I had 30 hours on it and the piston was still good. I wouldn't push it past 50 hrs though. Why take a chance on a $2000 overhaul

I would replace it just for piece of mind as they only have a small skirt on the piston.

Post a few pictures after you change it.
Would make interesting viewing and comparison for others.

That fact that you have taken it easy and do regular oil changes is why you have had good life out of it.

Replace with genuine piston/rings - the assembly is lighter than popular after market pistons. If you go to a heavy piston there is a case to change the rod and bearings as well. It can cause extra stress to the crank. I doubt the price would be much different either.

Good luck either way you go but I would take these posts as a warning.

thanks for the advice. i have a couple of spare pistons and a set of valves ready. i've had my mates engine apart when he did the valves.

only i am a bit concerned about the piston circlips are they quite easy to put in??

They are new circlips or ones that came with piston?

Here in the states, we have to order the oem rings separately-they do not come with the piston. The clips are easy to install, just cover the engine so the ring does not fall into it if it slips out of your fingers. Also install the clips so that the opening is up or down. If it was left or right, the up and down movement of the piston may allow the clip to fall out.

changed the piston over the weekend. when removing one of the old ciclips was inline with gap!

all went together fine i put the circlips in with my fingers. gaps downward

filled the engine with 20W50 car oil rode slowly for 15 minues, cooled. then rode another 15 minutes increasing revs. then drained and refilled with 10W40 Jaso MA oil.

will go to the track soon...

How did the old pistion look? Were there scratches on it?

Post a picture or two of the old piston.

Would be interesting to see how it has held up.

when i get a minute i will put some pics of the piston in my garage.

the piston looks perfect no scratches just a bit of carbon build up on the top which i cleaned off with WD40 and scotchbrite. it makes a nice paperweight on my desk. although the ring gap was slightly more than the new one it was still well within the limits in the manual.