They need to go through more heat cycles when breaking them in. So take your tome to break itin properly. (use Ct racing break-in procedure)

 

Wiseco pistons are stronger than cast pistons... but because they expand, first you have to properly warm-up your engine... but once it is warmed up they are able take a ton of abuse. They are racing pistons.

 

Well how does this sound. I've got an overbore wiseco high compression piston on my quadsport. On my first 3 tanks of gas i got on it a little bit and used some burst of speed and as long as it smoked when i started it up i rode as usual and didn't let it warm up. On the 4th tank of gas the crank went out.After a new rod, crank, and bearings i took it relatively easy for first 3 tanks of gas the got on it a little till 7th, then i really got on it up to my 10th tank of gas,but not real hard. Think its broke in good? I changed the oil on tank #5 and adjusted the valves. Beware if you do not let wiseco pistons warm up in the cold weather for at least 30min it will seize up.

 

I run a Wiseco in my 350X, the only thing I don't like is when you first start it it smokes. When it warms up it quits. If it uses any oil it is extremely little because I never have to add any between changes. Does any one have this happen?

 

I put a Wiseco piston in mine at the start of last year. I got the Pro Lite series and I would definitely buy another. Have had no problems with it the guys I ride with haven't had any problems either. I think whoever told you they are bad must have other problems cause they sure seem to do the trick here.

 

Wiseco use a lower silicon content in their aluminum alloy which makes them expand more. You need to allow more tolerance. It is not just because they are forged. Not all forged pistons have this expansion problem.

There are more problems on air cooled machines because the heat is not even therefore the extra expansion is not even.

The Wiseco installation sheet says to allow .003" for the 80mm piston in my FL350R. I use .009". I would prefer to use another brand if there was one available after using up both Honda overbores.

 

I just redid my 250r a couple of months ago. I ride in really cold weather.
I do let it warm up for a 5 or 10 minutes.
You dont have to spend so much time breaking it in. If you read the sheet that comes with the piston, it tells you that you need to run your bike for approx. 15-45 minutes a different rpm ranges to break it in.
I did just that, and I havent had a problem yet.
My saying is, "check those air leaks", those are engine killers.
Peace

 

I have wrecked Wiseco, Arias, and JE pistons(not on the same bike).....They all seem to melt the same.