Main Motorcycle: 2012 base bonneville
Join Date: Jun 2012
Location: coal township pa USA
Other Motorcycle: 2013 victory hammer
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reading in my service manual for the 2012 bonnie's it SAYS compression ratio in models with electronic speedometer is 10.2, is this correct? i believe my 2012 bonneville has electronic speedometer from prior readings. with triumph lower fuel requirements other aspects such as timing advance or cam shaft etc is prolly altered to control final cylinder pressure which is the bottom line pretty much to control knock. input appreciated since its my first bonnie since 1970!!! i am in the USA, do models differ over the pond, excepting emmissions of course
Yes, I've read that. A consequence of the raised CR is an increase in power and torque and the service manual does state that power output has increased from 66.1 PS at 7500 rpm to 68.1 PS at 7400 rpm. That's some 3% which is consistent with raising the CR by 1 whole unit.
I'm surprised they made a change of pistons... not saying I don't believe it, just shocked that Triumph actually made such a change. I know very little about the specifics of engine internal workings, but wouldn't a 10.9% increase in compression make considerably more increase in horsepower output? (I do know a little about math. )
Did they also change cams, or something else at the same time? And what was the reasoning behind the change(s)? Still confused.
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