Topic: 1976 CB750F: High idle RPM when started

[rieshunter]

Hi everyone,

My motorcycle:
1976 Honda CB750F Super Sport

My conundrum:
I recently bought a bike that had sat for a while and I am trying to get her running properly. Before yesterday, the bike (with a spurt of starting fluid in each carburetor) would start running for a second then stop. Yesterday, I took apart the carburetors and cleaned and air-chucked its innards. Today, I put the carburetors on and now she runs. The problem is that the bike revs very high when started (got up to 4-5k RPM before I hit the kill switch).

Other info:
When the throttle is fully depressed, the throttle rods are not pulled up.
The carburetors are tightly secured to the engine.
The intake boots on carburetor 1 are cracked on the engine side (I am suspicious of this, but it doesn't feel like the smoking gun).
The throttle valve adjustment of carburetor 4 is as pictured below (throttle fully depressed, valve freshly lubed). All carburetors' throttle valves look like this one. I have not done carburetor synchronization yet.

Thank you all in advance for your help!

Edit: Here's an imgur link (https://imgur.com/a/R6Y4J5y)

[ekpent]

 Are you familiar as to where the large knurled screw head is on the rack that adjusts the idle ? If you screw that screw out to a point to where the idle will not drop and its still too high and its no longer making contact at its point then the slides may be set to high on the synchro adjustments. Sticky slides or crappy throttle cable are other options as are air leaks which can be checked with some spray products.
   Note the screw head with the lines cut across the face at the left side upper of the carb rack.

[rieshunter]

Thanks for the response!

I adjusted that screw (imgur link: https://imgur.com/a/yES3JFZ) and the throttle valves sit much lower in the carburetors. This was the correct fix; the bike idles around 1.2k RPM. I took the bike for a spin (for the first time!!) and it rode like a dream.

Thanks for your help! I really appreciate it.

[ekpent]

 Glad your first spin went well and hopefully many more to come for you !