Honda CB750 Sandcast
The Restoration Shop => Engine Mechanical => Topic started by: bojje on February 22, 2010, 08:25:28 pm
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Hi! I would like to know why the first edition of carbtops, marked 28, are called 28 mm by many persons. I have a complete set and I have measured and compared the carbs thoroughly against the later normal ones. The only difference Iīm able to find are just the tops with their small adjustingscrews. The slide( I suppose You call it so) and the housing are all of 26 mm diameter. Out of that is the early throttlecable thinner and the rubberboots for the adjustingscrews are also much smaller. If anyone has found something that I didnīt, please let me know. If not, letīs call the first edition of carbs just 28 instead of 28 mm.
Thank You so far and Iīm waiting for Your answers, Bo from Sweden.
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Hi Bo
Pretty sure the term to describe the caps has been around longer than the club.
Looking forward to hearing more on this topic.
Steve
PS - Are you still planning to attend VMD ?
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Fellas,
Simply refers to the amount of slide travel or the height from the bottom of the venturi to the top. The slide has a travel of 28mm from closed to open. The gap between top and bottom of the casting in the center (venturi) is 28mm. If it isn't then I'm wrong ;D
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kp: well done.
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I had a set some time back and i think the top screw rings are the same size as used on the later linkage carbs K1 on TC
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Hi again! Thanks for answers about "first carbtops". However, I have looked them through thourougly and compared with the kind with 6 mm cables. The differences Iīve noticed are as following: first kind-41,5 mm slides, later kind-46,5 mm slides. first kind-tops marked 28 and lower top screw, later kind-non marked tops and higher top screw. first kind-small cable adjusters to be adjusted with a 7 mm tool-later kind-bigger cable adjusters to be adjusted with a 10 mm tool. first kind-5 mm cables and a thinner devider(1 to 4 cables), later kind-6 mm cables and a thicker devider. First model top screw look similar as the one from K1 and K2 but it isnīt ecact the same. Iīm pretty sure no one else will notice the diference, if someone has mounted the K1 top screw, eccept the mounter himself. Regards, Bo from Sweden.
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Bo another difference was the spring the later one is longer TC
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Could i use later kind, 46,5 mm slides, with the first kind tops, marked 28? I am using 28 tops from Steve Vanzetto and told to my mechanic that he must machine the slides from 46,5 mm to 41,5 mm. He told me that it would not be necessary. What could be the consequences?
Marcello