Clearly never stated in any CB 750 or 750A Service Manual, this "backyard technique" has worked well for us in the reinstallation of the carbs after a thorough carb rebuild. Carb rubber "boots" we've worked with are normally rock hard and not pliable in any way, shape or form.
After you've very carefully pried the boots off the head and carburetors take the boots and thoroughly "grease em' up" on the inside in preparation for reinstallation. Normally because of larger size of the boot going onto the head (750A), you can manage to muscle them on. Once on and (with the boot clamps installed and opened up as much as possible) take a board and lay the board across the open boot ends and rotate the rubber boots around so all 4 boot openings are flush with the board (you can maneuver the boots around by reaching in and turning each boot to insure they are flush with the flat board). Once all boots are flush to the board tighten the clamps up so the boots will not move. Take the smaller clamps (750A) and slide them over the boots in readiness to accept the carburetors. Take the carbs and align them to the boots. (Now comes the real "backyard technique") We use a ratcheting tie-down and hook each tie down end to the front frame down tubes on both sides forward of the engine and align the strap as horizontally as possible with the board placed over the carb intakes. It will now take only 3 or 4 tie down "clicks" before those carbs just slip onto the boots with a resounding clunk! Tighten the 4 small clamps and your in business
Both of the 750As (1977 and 1978) we purchased over the past three weeks were discovered in barns and sheds. Both have been really neglected and non-running for years. They both have benefitted from this carburetor "less than normal" installation technique. Having slugged with carb reinstallation on a number of old and forgotten 750As and 750s this technique has worked for us (my neighbor and I) the best. In our case, we've also found that the cylinder numbers imprinted on each boot were not exactly/directly on the top of each boot when carbs are installed.
If you are or have ever been struggling to get the carbs/boots aligned just give it a try next time your struggling with carb reinstallation and see if it doesn't work for you. Hope this helps someone out there!!!!!!!!!!!!
