Valve changes can add volume to a cylinder, don't bet your build on your assumption the heads were 87cc from the factory.

Total head height (gasket to gasket) is 3.75" grab a measuring tool and a calculator
-.06" should give a height of 3.69" chamber volume will be what it is at that point.

If you problem is a compression issue fix it, spend your cam money on pistons as was mentioned earlier.......go form there.

Why do you need new cylinders for a piston swap?

 

Would not need new cylinders, but would need.005 or .010 oversized pistons and would need to rebore cylinders. My heads were milled .020 before andI am milling another .030 for a total .050. From everyone I spoke to, that is an acceptable amount and should not have figment issues with intake. If so, I will mill intake .010 - .015.
Heads are being milled now, old cams are out, new gear cams going in today - just waiting on new gasket set and comp releases to be delivered. I am getting excited to get this back together, get it tuned and go for a ride!

 

If the valve are bigger u might need to check for valve to piston clearence depending on the TDC lift of the new cams. Just something else to think about.
What size motor do u have now?

 

Anyone know the ratio of how much you take off the heads and how that changes cc of the heads?
Like if u take .060 of the heads. How many cc does at that make the chamber?

 

.007 per cc; .060" is equivalent of about 8.5ccs

BTW, your deck height is not 3/16" to 1/8". Early TC88 pistons are down in the hole .005" to .007" and YMMV but not that much. Don't estimate; measure.

 

I put 6-6 cams in my 2008 FLHTC. I had the heads milled 0.040" and installed a Cometic 0.030" head gasket. Without compression releases, I have no issues with starting even when hot. The independant mecahnic I had doing some of the work used a file to fit the intake manifold. I think I paid $40 to get the machine work done. I believe I could have gone another 0.010" without much problem, but I would want to measure everything very well to make sure there is no interference. I don't know the actual compression ratio but the bike seems to run very strong with this setup.

 

Thanks everyone for advice. I ended up cc'ing heads and milling to 89.5 cc's. With pistons, headwork and .030" gaskets, I should be at around 10.25:1 CR. running TW6 cams at 285' above sea level with a 4degree advance. Go everything put together and rode briefly around town - needed a good tune, but it was driveable the hour to the shop. Unfortunately, on the way to the tuner, I got caught in a light rain on a very oily road, and the truck in front if hit his brakes hard. I applied brakes and immediately started sliding like I was on ice. Had to lay bike down and slid under truck. Bike's been in shop waiting on repairs. As soon as it's back together, it's getting tuned. The short rides I got in showed some good potential, so I am excited to get it tuned and see how it runs.

 

Glad to hear your okay! Good luck with the dyno

 

just wondering why your shop would mill the heads without cc`ing them before & after (????),glad your OK

 

Sorry - heads were milled to 79.5cc. Original shop milled heads .020,but never cc's the stock heads before. He just based expected CR on stock 85cc heads. When I starting looking at bumping compression for the TW6 cams, I had them cc'd and found they were almost 85 cc's after the .020 was removed. When I had this done originally, it was the first time I ever had any headwork done and trusted the shop to do it right - live and learn. Just glad I knew more going into this the second time - at least I have a lot more confidence in the engine set up. I always thought my low end was a little soft before and was chasing down different exhausts trying to improve low end torque, but really think the lower compression was the culprit.
As for accident, I was a lot luckier this time than my one a few years ago. Split elbow open, both elbows hurt pretty bad from hitting street and truck, left knee is cracking and popping some, and a little road rash, but I walked away.