Replacement Pistons for EVO

[Don D]

Looking for .020 OS pistons for an EVO with Screaming Eagle Performance heads. How about using a 10.5 KB forged? Are chamber or dome mods needed?
Thanks

[thumper 823]

From what I think I know- KB makes    an hypereutectic  piston .
I have always heard they dont work.
I dont know that to be a fact.
Perhaps their process is wrong?
Porsche has used Molly hypereutectic  fopr years with even their high Horsepower turbo air-cooled monsters.
They work.
Now thats a fact but, but  KB stuff I have no proof of just rumor control.
SO do your homework.
Rember any set of slugs will capture the breeze and get forced dwnward.
The trick is to do it as efficiently as posable.
If you are going O.S just for power then don't bother.
If you want more power take advantage of more modern squish and combustion chamber designs .
Axtell has done ithat, and many venders will sell you their stuff cause it works.

Their nodular cylinders eliminate the leaks and with a 500 lift cam you will be twice the power of stock.

The devil is in the details.

[wfolarry]

The SE heads have a different combustion chamber so if you go with a dome it has to be for that head.
The chambers are 72cc so you get a compression bump just bolting those heads on.
If you still need a compression bump you'll have to machine the piston top.
If I remember right I machined the top so both sides matched & it fit. Maybe do a little trimming.

[thumper 823]

As some of us have said over and over-

Take a sheet of paper and list the goal at the bottom of the page for your engine  / bike
Now, fill in in the blanks at the top to get there or..you will end up throwing money and parts at it and never be happy.

Vergin heads need at least 0.050 removed just to start to get anywhere and more like  0.070
I would stay away from SE stuff as all they did was copy S&S  or someone else and charges you double.

I strongly would consider Axtell redesigned chambers and angle tops.

[Don D]

This is a repair job of a strong running stock block EVO, 95hp with SE57 cam.  I will probably use the KB920C+.020 forged pistons and even after remodeling the dome it will give me about the same CR as the old setup. I can still get the SE JE pistons at + .010 but the cyls are +.005 already with light scratching and IME that is a little of a dicey move to expect it will clean with Torque plates on. I may bolt them up and rough hone and see what it takes to clean. Larry, thanks for the help.

[thumper 823]

I would like to see the rest pf your mods

[TorQuePimp]

This is a repair job of a strong running stock block EVO, 95hp with SE57 cam.  I will probably use the KB920C+.020 forged pistons and even after remodeling the dome it will give me about the same CR as the old setup. I can still get the SE JE pistons at + .010 but the cyls are +.005 already with light scratching and IME that is a little of a dicey move to expect it will clean with Torque plates on. I may bolt them up and rough hone and see what it takes to clean. Larry, thanks for the help.

Get ahold of Mike P at diamond
They don't that that exact dome......but have one works that I came up with to use for a few Evo heads
Similar to the dome v&h uses on the TC 107 pistons
If you wanna make a chamber mold I'll send you a kit for the cost of shipping

[Don D]

I will give them a call for a quote.
I need some TC pistons too so was going to call them anyway.
Thanks

[jsachs1]

I've cut EVO style Wiseco 10.00:1 pistons to fit Branch heads that have come in.(No problem at all with reliability). The Branch chambers were very similar to the SE bathtub chambers.
John

[Ironheadmike]

Wiseco makes a SE piston

[wfolarry]

Wiseco makes a SE piston

K1716 +.020. 
Usually if you find them they're only +.010. Missed that one.

[Hillside Motorcycle]

I've cut EVO style Wiseco 10.00:1 pistons to fit Branch heads that have come in.(No problem at all with reliability). The Branch chambers were very similar to the SE bathtub chambers.
John

^^^^^^^^^^^^

[prodrag1320]

Looking for .020 OS pistons for an EVO with Screaming Eagle Performance heads. How about using a 10.5 KB forged? Are chamber or dome mods needed?
Thanks

whats wrong with the pistons that are in it now? might be easier to get new cylinders & use the existing pistons (or get new ones & go with the .010 that WFO larry is talking about

[Don D]

Cylinders were hand rigid honed and screwed up, +.005. I was able to just bring them in at +.020. Used the Wisecos I got from Drag, thanks for the advice. Bike is back up and running well.