I’m thinking about going from 107 to 117 for my winter project. I have a set of s&s 5.013 tall cylinders sitting doing nothing. Can I have them machined to the 4.878, or what the build requires to zero deck, height, or am I just complicating things again??

 

How are you going to get from 107 to 117? What model, year?

 

2014 Breakout. My reasoning for it is that I moved from Houston to North Colorado, 5000ft., I could tell I lost some power. I did a hp pull at Sturgis and was disappointed. Checked ccp when I got back to Colorado, 160.
Heads were built for bigger cams. Andrews 57h in it now, purchased tman660ps-2 and springs. Pipe is Road Rage 2. Tmax tuner. HPI 58.
If I used big boys calculator correct my combustion chambers are about 97cc’s. So, thought maybe best way to get compression up would be bigger bore.

 

You could get pistons with the correct dome to get to the compression you need and have your heads milled to get the chambers equal. You can then have your current cylinders zero decked. Zero decking is a detail alot of backyard builders skip but it's important because it sets the squish and you'll be closer to the compression numbers you should be at. Getting to a 117 is going to require you split the cases for some machine work...this is where it gets expensive. At that point the cost to go to a 124 isn't that much more. Nothing wrong with a 117...I have one myself and it runs strong. As long as your supporting parts, like exhaust, throttle body and clutch/primary, can handle the 124 its probably the way to go.

 

My first thought was to purchase bigger dome pistons, but my cylinders have 15k miles on them and I figured it’s probably past the possibility to just hone them for new pistons and rings. So, I thought maybe the cylinders I have can be cut down, buy pistons for them, send my 4-3/8 crank to Revolution for true and balance, bore the cases.
I saw a price sheet for Revolution’s crank work somewhere in the past, seems they were considerably less expensive than Dark Horse. Which is why I considered the 117 option. Of course, now I can’t find where I saw that.
If I go 117 I’d like to hit 130’s hp and torque. I don’t think I’ll need anything too special done to my crank for that.
My heads were built for a 107. If I get to 124, I’ll probably have to have them re worked?? They flowed about 250 at 28”.

 

I assume the cylinders are for a 124.. Why not cut them to 4.927 and use a 1.090 piston CH?

 

Assuming your S&S cylinders are 4.125 bore, you will still have to bore cases for the larger dia spigots to fit. If you want to go that route cut cylinders to 4.912 and use pistons with 1.083 comp height instead of the S&S pistons which are 1.050

Whole lot easier to keep 107, go with domed pistons. At 15k cylinders might clean up with light hone. Your machine shop will have to figure that out. Worst case you have to get new cylinders for 107

Save the 660ps2 for better heads with proper headwork

 

Probably want those heads flowing 300+ to make those cams shine

 

Not sure what heads you are using but 93cc seems a little big.. It's got 110 heads on it?

 

They are the 103 heads that came with the bike. Wolfgang Grasser did the work on them. I remember he really sank the intake valve, I guess the chamber cc grew with the bowl work also. I didn’t have anything milled off. They were 190ish ccp at sea level with the Andrews 57h.