12-09-2015, 10:44 PM
(12-06-2015, 06:15 AM)Roger the shrubber_imp Wrote: I've been studying up a bit on our beloved CB, and one of the persistent oddities I discovered was the unusual decision by the engine design team to give the big CB some character by engineering in a little roughness. Apparently, the engine was deemed "too refined" so they retarded the intake cam timing on just two cylinders to give the bike some soul, I guess. Stranger still, they went through the trouble of utilizing a counterbalancer to make the engine smooth! Seems counterproductive.
Anyway, this assymetrical cam timing comes at a cost in achievable top end horsepower I believe, so I'm going to look into this by buying a set of stock cams and taking some measurements. My engine builder and machinist can re-profile the intake cam to a symmetrical timing configuration, perhaps even altering the duration to get more horsepower out of this powerplant. The cylinder head is also modestly configured with relatively small port area, so perhaps some improvements can be made there too.
115-125 hp seems achievable, as long as I can get the engine management system to play with these changes. Anyone else look into this or know about it?
Without sleeve bore & stroke in addition of cams those ## are not obtainable. I've researched last year and no one has a kit available. Changing cam lobe may net you about 5 hp with a modified ECU and hours of dyno time. This would not be cost effective.
This is not a GS1100E motor that you can find a 1465 block. The CB putting out 125hp would require more modification than cams & bored, probably a new block which are not available.
Edit: Roger, Honda has the hardest ECU to crack without drilling it open, Don is the only guy I know and he's in PA. Any modification done to the cams would require the ECU to be re-mapped for timing and fuel. You would have to ship the bike to PA for dyno time.
Its not like the old days when a tuner can pull out his carb kit and change needle valves and main jets to tune.