The SOHC/4 World Tour is in under way.
0 Members and 1 Guest are viewing this topic.
I was just curious about your exhaust set up. The 550 firing order is 2-1-3-4. To get the most even flow out the two exhaust exits, a crossover is required. The crossover type is said to give the engine better low and mid range power characteristics such as is needed for street machines. But, they seem to be rare. I ran with a 4 into 2 and parallel head pipes for years. It works fine. If both your exhaust systems are the same, it shouldn't matter which set you chose. If you feel the flow restriction on one is different from the other, then definitely chose the one you want before fine tuning the carbs.
You have to fit the 650 cam 'gear' instead of 550 sprocket which is the only thing I can think of which may be different although I don't think they are.
It should drop right in and work as intended.You have to fit the 650 cam 'gear' instead of 550 sprocket which is the only thing I can think of which may be different although I don't think they are. If You do realise you will have to rev it higher though, no more plodding around at 2~3,000rpmPJ
Ok, I am actually getting work done on my next motor, and I started looking at my cams I have.First I measured the '81cb650c cam I have out.Seemed odd... I swore I rembered checking my '79 cam, and it had more lift....Well, while out in the garage, I pulled my '79 cb650 and '81cb650c cam as well as the ebay special '74 cb550 cam I bought to see the interchangeability.And started measuring lobes and base circles.WOW.Either the '79cb650's cam is WILD, or I got a doozy of a deal on that parts bike.The measurements I am coming up with are as follows:550(1974)1.362 lobe 1.3821.110 base circle 1.1100.252 lift 0.272650(1981c)1.360 1.3801.105 1.1050.255 0.275650(1979std)1.390 1.4031.110 1.1100.280 0.393Does anyone know of someplace that shows lift of different stock cams for honda 4's?I searched, but cannot find anything about the 550's stock lift or the 650's.My manual shows the "cam lobe height"specs as intake : 1.4062-1.4089exhaust: 1.3903-1.3966wear limit intake :1.40wear limit exhaust :1.39So did the "C" get de-tuned?Anyone out there have a cb650 or 550 cam they can measure to compare against?l8r
Are the rocker arm ratios the same between 550 and 650?