About a year ago, I ran across a great used package deal I couldn't pass up. After working on the boat as a side project, I really want to return the mystery worked Zen 260 back to stock. What I do know is that the previous owner put a Lightened piston (It's dimpled like a golf ball and shaved), advanced the timing, added a thinner head gasket, and opened up the port on the intake. Well, I have concluded after running the hydro, the intentions were for higher rpm and unfortunatly he tweeked the torque right out of it coming out of turns. So I have a spare 257 carb and a fresh piston (Stock on the way). Will I have a negative effect adding the stock piston back with advanced timing or can I get the pop and compression back with frssh parts. The jug looks clean but the piston was scraped up with scratches.

Assuming the cylinder is still good, and timing numbers not out of this world:

Putting in a new piston will not do any harm..in fact, a lot of the guys that did the "golf ball" mod to the piston also used the piston skirt to set intake timing. If this is the case with yours, putting in a new piston will bring down intake timing closer to stock and might help out considerably (if need be you can always re-tweak intake timing up). If the builder did NOT grind the piston skirt to set the intake timing, well putting in a new piston won't change a thing with timing. So in short I don't think you can lose either way. I would replace the piston and ring.

You should check your intake and exhaust port timing numbers before you start changing anything...this way you will know what you're working with and also have a reference to compare your changes to. Otherwise you're just shooting in the dark.

Piston skirt? Not familiar with that term. I will try a search but if you get a chance, can you tell me what that means?

I love torque and I hate sacrificing it for a couple mph's on the high end. I have not messed with timing but I know that the previous owner played with the key kit and put the numbers way up. I want to bring the motor back closer to stock so that I have a base line and can take it in the direction I want to go in. All the internals imcluding bearings and seals are fresh and since I have had the motor, I have run Camp Fuel and HP2. The lightened piston had visual wear on it so I am hoping a fresh stocker will give me some needed compression...at least that is my hope.

Piston skirt....got it. I put the piston and jug under a bright light and can see the work of a Dremel Ninja--probably green belt cause it's a crappy job. I have a spare jug that I refinished a while back that I can use cause this one's got to go. Yeah it looks like the timing was advanced by rotary tool so this should be fun taking her back to stock and slapping on a 2716 2 blade instead of these tiny 3 blades I have been working with to stay high on the tach.