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My 750F2 project.
Laverda Dave:
Is that the reason why the F2 suffered with premature valve guide wear Nigel? I assume if the valve was higher in the head this would have an effect on the cam/rocker to valve stem geometry compared the earlier models unless of course Honda accounted for this in the design of the F2 head?
K2-K6:
--- Quote from: Laverda Dave on November 27, 2023, 10:43:44 PM ---Is that the reason why the F2 suffered with premature valve guide wear Nigel? I assume if the valve was higher in the head this would have an effect on the cam/rocker to valve stem geometry compared the earlier models unless of course Honda accounted for this in the design of the F2 head?
--- End quote ---
Yes, the geometry didn't change as far as I understand it. The rocker arc is compromised in its contact with the valve to give slightly more sideways loading through it's initial travel, coupled with raised spring rate for higher rpm too. Tgey deleted some of the oil drainage holes from head too, this to keep more oil around the valve gear prior to going back down into sump.
Honda realised this with development of endurance race 16 valve head onto CB 750 bottom end with the first "RCB" motor in 1976, I think. Then development of the road going twin cam motor.
Cb750r:
I think the 77/78 bikes used a less durable guide material, heavier valves, more lift in the cam, and poor designed retainers. Also factory tuned leaner due to smog era. All of those reasons have given the big valve SOHCs a bad reputation. However they still had bigger valves so it’s a great base for a high flowing head when you replace everything that was a disadvantage!
Unfortunately for my pocket book it also means I have a head and cam that will allow more airflow than my stock carbs will allow for so it seems I’m also in the market for a larger bank of carbs.I will cross that bridge a little later but I’m leaning towards a set of Mikini RS34. I have the case haves a coat of paint over the weekend.
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Cb750r:
Installed my freshly painted bronze top clamp and also found a nice little fly screen and installed it. [ Guests cannot view attachments ]
andy120t:
Looking good . I like your headlight/screen brackets - did you make/mill them?
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