I recently ditched the air pods for an air box on my '74 CB550. The decision was mainly due to loss of power between 4000-6000 RPM. Otherwise, they were acceptable. At the recommendation of another forum member, I found an appropriate OEM air box with the K&N adapter. I added new boots and a new air filter. The isolator boots between the carb and the intake manifold are also relatively new.
The jet configuration on my pods was 40 slow, 105 main, and 4th needle position (factory). For the new air box, I went with 40 slow, 100 main, and 5th needle position (one richer). The jets came from 4into1, and even though the 40's were the same, I installed the new ones. I only bought new 40s because I couldn't recall what was in there originally. The air screw is 1.5 turns out.
When I first started it up with the choke on, it started up fairly easily. It sounds good. If I slowly let off the choke after warm, it stays alive until about 80% open, then dies. I tried giving it more throttle, but that is not the solution. Below is a video of the issue with the engine already warm.
I'm seeking advice/tips to help me troubleshoot. Seems like maybe there's a vacuum leak somewhere? Can I assume upstream of the choke? I'm thinking I may put the old 40 slow jets in tomorrow. Is there anything special I need to do to seal up the new boots between the carbs and the air box?
Really scratching my head. Everything seems clean and tight.
On a side note, getting the carbs in and out with the air box is REALLY tight. It feels hard on the boots. Any tips on removing and re-installing the carb body?
Thanks in advance.
