Re: CB750 A2 / Hondamatic two-speed with 4 into 2 exhaust

Posted by TOOLS1 on Apr 18, 2014; 2:52pm
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/CB750-A2-Hondamatic-two-speed-with-4-into-2-exhaust-tp4050250p4050253.html

Nice bike. I have one it that color also. That hose you are asking about is a vacuum hose for the throttle kick-up. When you put the bike in gear it will increase the idle speed. However I run my bikes with the system disconnected. On the boot being cracked, yes it will cause a vacuum leak. Those must be sealed. No one makes boots for the matic. When mine went bad I switched over to K model carbs which boots are still available for. However I might have the "one" you need, which one is it? That is if the rest of yours are good. As for the not running without the choke on, it could be just the cracked boot, but I doubt it. These carbs a notorious for plugging up, especially the pilot jets. I have a write-up in the repairs section on "how to remove the pressed in pilot jets". Also the accelerator pump circuit is often clogged. You should have fuel squirting out of the four brass nipples in the throats of the carbs when you give it throttle. These can be cleaned, but are a pain in the butt as they have two tiny, and I do mean tiny check balls, and a even tinier spring that likes to fly.
TOOLS