OK

I have a 117 SE kit in a CVO with a 259E and roller rockers etc and MVA heads.

The 117 factory kit says 9.9 CR but the MVA heads supposedly have a larger combustion chamber than the stock heads so my CR is probably less than 9.9.

Any advice on how to up the CR to 10.5-10.8:1 ?

Mill the heads (how much)? Crowned pistons (which ones)?

I have this kit along with the MVA heads, part # 16925-11:

https://www.harley-davidson.com/stor...B&gclsrc=aw.ds

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Thinner gaskets??

 

Send your stock heads to a good head guy to be reworked properly and sell your MVA heads.

 

Reworked/Ported stock or S&S heads and custom dome pistons.

 

To be honest, your stock 110" heads will pretty damn good with the 117" Big Bore kit.
Like "FLSTFI DAVE" and myself, we sent our 110" heads to Don D. @ at HD STREET PERFORMANCE for treatment, new valve springs guides, valve springs, etc.

IIRC, Dave is about at 11.4ish on compression and producing some stellar numbers like 138HP & 140ish TQ.

I'm right at 10.8 compression and will be going up a bit more because I will most likely be going to a bigger lift cam this winter.

One thing I did was sent my crank to DH to get the works to support the big gains by going with the 117" Big Bore Pro Race kit!


YB

 

I wouldn't modify those heads without consulting an engine guru! As suggested above, talk to a competent tuning shop to upgrade your engine, which is essentially what you will be doing.

 

Don D is an excellent choice...