Im helping a buddy out now with a 2005 dyna with a 88 and 510 gear drive cams . He has money with harley and will be buying Harley parts. They have two big piston kits one comes with 95inch flat top pistons and the clame is 9.4 cp the other kit has semi dome pistons and is 9.7.1 ...now this dealer will not use thinner head gaskets they use all stock stuff so for him what would work better with the 510 cams the flattop 9.4.1 pistons or the screaming eagle pistons semi dome 9.7.1 pistons? His heads are staying stock

 

The flt tops are cast and low comp,not good wit the S&S cam. The other pistons sound like the forged 10.25 comp. pistons. They would work well ,but wOuld probably need an adjustable ignition,. I don't think there would be a problem with valve to piston clearance.

 

The book says there forged and will make 9.7.1 with stock heads..like like there a small dome

 

A lot of horsepower can be found in a good set of heads....

 

The S&S 510s are top-end cams. For a 95" build with stock heads and gaskets, I'd go with Andrews 21s or maybe SE 203s. Do a search for Joe Minton's 95" build w/Andrews 21s.

 

No changing cams is not going to happen he just bought them 510s and installed there like 1800$. I hate the 510s myself they come on to late im glad I did Andrews 21s for my own bike

 

Just did a little checking around. The 510 cam are for 88, 95, 96 CID engines with compression ratio below 9.7:1. Use with stock un-ported heads. RPM range 3000/5500 RPM... Good luck..

 

HERE you go again . Bolt in 510 cam in set comp 9.8 to1 so 9.7 to1 will work . I had this setup but I had my heads done and sure didnt pay 1800 for cams sounds like another half job.The mackie 510 s did the trick 1500 to 5000 pulled like a train nice combo if the numbers on install match. 040 head gasket will get you to 9.8 to 1 with the high comp pistons.I had comp releases installed.

 

Magnum I did this exact build with the flat tops on my road king. No head work. I wanted a cam that pulled well riding 2 up and loaded touring with the wife. I haven't been disappointed yet.
RR

 

I would not use the "domed" pistons, in a twin cam the "squish" happens at the perimeter, the second reason is the higher compression might give you issues without compression releases with your starter...
the .510 cams should not require headwork, you might also consider a feuling oil pump and cam support plate...it'll run 25-30 degrees cooler...