Reddit reviews K&N 81-0221 Fuel Filter
We found 3 Reddit comments about K&N 81-0221 Fuel Filter. Here are the top ones, ranked by their Reddit score.
High volume, low pressureSimple to clean by backflushingAvailable with 1/4Inch flangeAvailable in single or 12-packs
The octane level of the gas should not affect the idle. You could try changing out the fuel but I'd bet there is some other issue. I had a '72 cb350 myself for several years and never saw any difference in the running condition based on the gas type.
The idle jet inside each carburetor has a very small hole that allows gas to pass through. More than likely there is some small debris blocking one of the idle jet passageways.
Can't tell from your picture, but you should definitely have an in-line fuel filter that keeps debris from the gas tank from getting into the carbs.
I have heard of people having luck with running Seafoam through their tank to clear out the carbs. But in my experience owning a CB350, removing and cleaning the carbs was a process I inevitably had to do a couple of times a year. It really isn't that difficult to do.
Edit:Spelling
That's very helpful thanks! I was thinking this one might work.
Clean it out and replace the gaskets, then add some inline fuel filters below the petcock since the mesh on the petcock is gone. Something like this is what I use: https://www.amazon.com/K-N-81-0221-Fuel-Filter/dp/B000E2AR70