Searched but didn't find anything. While doing some research prior to ordering 76* offset crank for a Triumph T140 project, I found articles on twisting cranks in Yamaha xs650's where the crank halves are splined so easy to separate, twist and reassemble at 277* without requiring any special pieces. Has anyone done or considered doing this on the Honda 305 crank? Since the cams are also splined to center sprocket carrier they could also be twisted. I know the cams have a special spline so that they can't be assembled wrong but this could be overcome if someone was driven to do so. I've never had a 305 crank apart so don't know how feasible this would be or if the halves could even be reassembled at a favorable offset without requiring machine work or new pcs. manufactured.
The goal would be to create an offset crank (preferably 90*) to smooth the power, reduce vibes and eliminate much of the rocking couple created with 180* crank. Basically creating small V twin in sound and personnality with the advantages of a V twin in a parallel twin...any thoughts or has it been done? Mark
CB77 offset crank?
Interesting project.
If I were doing it, I would start with the cam and work out what the spline pitch is. Once you know what angles the cam can be indexed to, you can then do the crank. The ignition will need re-phasing to match the new crank angles. You could just make up a new points plate for that if there is sufficient clearance between the two sets. If not you will need a new points cam or electronic ignition... The centre shaft of the crank is smooth so you can potentially set that wherever you want. Sensible to work in the fixed intervals that the cam spline allows, though. You could always try this...... http://www.google.co.uk/url?sa=i&rct=j& ... 5178299097 Please send updates. G '60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F 305 CrankG and Mark,
I probably should have checked this out more fully before responding, but my memory is that the crank can only go together one way. That is, you couldn't change the relationship of the two sets of counterweights at the center shaft without moving one side off of the center line of the crank. You might be able to relocate the shaft on which the big end sits by drilling new holes in the counterweights and plugging the old ones, but I think there are some oil passages that wouldn't line up then. Not sure I am remembering that part right and maybe a guy could drill holes to make it work. When you were done, you would probably have to have someone line up all the parts of the crank around the centerline. This seems like an awful lot of work. As they say, with enough money you can do anything, but it seems to me a guy could have pretty good time on the kind of money that would end up being spent. Please correct me if I am not thinking about this correctly.
Re: 305 CrankConbs,
The crank will go together however you clock it. 180, 360 or whatever. But if you assemble it 90 or 270 will it be balanced is the real question. Tim
90 Degree CrankThanks for straightening me out, Tim. I see it now.
So, the question is whether each of the sets of counterweights is balanced to the weight of the respective con rod and piston alone or if the two sets are also set up to balance each other. If the Superhawk and Dream cranks use the same parts (just turned 180 degrees) it seems like it would have to be the former. Anybody know?
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