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[wichitagreg]

Does anyone know for sure what the compression ratio is in a "Street Legal Stage II 103 Kit" as installed by a HD Dealer?

2009 Ultra, Flat top pistons, stock 96 in heads, SE255 cams.

I was reading about the police 103's, and they have a 9.6 advertised, and the stock 96 is 9.3.

I'm curious.  I'm considering running mid-grade fuel in the colder months.  Engine temp will not exceed 190 or so, and my elevation is about 1400 feet.  I figure 89 octane is probably better for my bike that 91, may burn more completely, and reduce carbon buildup.

Greg

[skyhook]

there are several factors which determine static compression...head chamber volume is usually 86cc, but ranges from 84 to 89, not always equal on a matched set...deck height can be as much as .009" down the hole...which head gasket is used...just a wild azz guess, I'd say 9.8...ignition timing is way retarded in '07 and later bikes, so you can probably get away with mid-grade fuel in cool weather

[spydglide]

Does anyone know for sure what the compression ratio is in a "Street Legal Stage II 103 Kit" as installed by a HD Dealer?

2009 Ultra, Flat top pistons, stock 96 in heads, SE255 cams.

I was reading about the police 103's, and they have a 9.6 advertised, and the stock 96 is 9.3.

I'm curious.  I'm considering running mid-grade fuel in the colder months.  Engine temp will not exceed 190 or so, and my elevation is about 1400 feet.  I figure 89 octane is probably better for my bike that 91, may burn more completely, and reduce carbon buildup.

Greg

Never really heard much about that....I'd always thought the hotter/quicker burn was better... ...shows what I know.     har!  spyder