Dominant piston v4 tight squish

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Joined
Sep 23, 2019
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Location
Park city, UT
Installed the piston today. Tried no gasket first. Makes contact. With the base gasket and hylomar it might have 2 thousandths or less . Why so off? I've heard of earlier versions running no gasket. Is the v4 that different? Like 40 thousands different?20191021_115941.jpg
 
I dont think so. Squish was good with no base gasket and factory piston. It seems like it's a whole gasket thickness off.
That would be accurate considering gaskets usually compress down to about .020"

The only other thing I could think of would be the case was machine differently than most saws. But that is not likely, the Pistons just off I guess.
 
I'm checking it with thicknesses of paper. Binds on this. It's all I have to work with at the moment.
 

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Yeah. Trying to get an idea. No calipers or solder. Sad because I used to work at a machine shop. I reused this gasket and the hylomar may have caused it to compress more than usual the 2nd time around. I'll get some supplies together in the next few days for an update.20191021_232811.jpg
 
Send it back, drop in a 268 windowed piston with a .040 pop up machined on it. Way cheaper and it'll turn a stock saw into a beast with 190 comp.

I actually have one on hand. I mail it to you for $55. Its a meteor with caber ring. These dominant pistons crack me up.
 
That piston looks to the eye to be a lot higher from wrist pin to top and front edge looks to be sloped down, is that the case or just illusion from picture? Also looks like a thinner ring than those stock 1.2mm's. Maybe @blsnelling can enlighten me. I am not a porter, just a saw hack.
 
My biggest gripe is its cost. $110 plus shipping. That's half the cost I charge to do a full port job. From the pic it looks like they also grind the edge to have the exhaust open sooner, and it also looks like the skirt is shorter. So you get a compression bump, longer exhaust and intake duration. Which is all good stuff, but what about the transfers? Does that mean the blow down is increased?

The 268 piston does all those things except raise the exhaust, and has a single ring. $35 piston and a few bucks to have someone machine it. But then on top of that the 268 piston is very light. Throttle response is great!

Maybe I need to start a thread about this to save future people some money.

Edit: so the crown does look higher which means the piston is ground on just one side to put the exhaust back to stock height. But again what about the transfers? Does blow down move from 23 to 26?
(I believe 23 is stock..)
 
It's a custom Wiseco piston. The price is not out of line at all for a custom forged piston.

As sold, the crown is not beveled. It is a pop-up. At least that's how they were when I was sent samples. Either it's the lighting, or this one was modified, or they've changed the design again. Do you have a pic of the crown?

You're only charging $200 for a complete port job?
 
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