Twin cooled
 

Does any one kno what cc’s the stock combustion chamber size is on a 103 twin cooled engine.I purchased a set of cnc ported screamin eagle heads and im tryin to figure out what the size of my stock heads should b and if these have been milled ? Thanks for all replies and info !

IIRC, no different from the air cooled 103 heads; 85cc-86cc.

My head porter did a "light cleanup cut" on the sealing surface, arrived at 84cc.

'15 wethead.

YMMV

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oh ok thanks i was thinkin thats how they raised the compression compared to the air cooled ! I cc’ed the screamin eagle heads and keep comin up with 78 cc .

We've had many come thru here, but have never cc'd them, prior to beginning work on them.
If you've cc'd them, and 78 is your number, then they have been surfaced about .040", +/-.
Scott

scott can you tell me what exactley moco did to raise the compression on the twin cooled (water cooled ) i have ask this a few times and never realy got a forsure answer the heads have a pear shaped combustion chamber not like the standard oil and water cooled bikes ? Thanks harley tells me they use a .045 head gasket ! Thanks

HD lists compression for both 103 motors, air cooled and twin cooled, at 10:1; compression is the same for both.

oh i thought air cooled was advertised at 9.7:1 an twin cooled at 10:1?

Not the HO103 motors; both at 10:1; the "regular" 103 is, as you point out, advertised at 9.7:1.