Hey AncientDad, I saw this in the post on a CB350 that could not reach above 65 mph. I'm interested to know about changing spark plugs to help with a rich/ lean condition. My engine is currently apart for a rebuild due initially for a stripped spark plug hole that I was going to have TimeSerted, still am on both holes since the machinist says they are stronger then the original head but getting back on topic. On my bike I had the spark plugs both running nice in tan with the exhaust at the time. 2-2 with Vintage VW Exhaust Tips. The bike ran loud as expected and would not pull over 7,000 rpm's.^^^add to that timing and the advancer unit operation. and if you're running a bit rich, heat range 9 plugs isn't helping either. you should be running B8ES to start with and could run B7ES if a bit rich, but getting the jetting closer couldn't hurt either
I finally built a 2-1 exhaust after looking for months for the elusive and probably out of my price range Hooker 2-1. Benjie's was also out of my price range. The 2-1 I built uses a 1.5, 1.5 to 1.75 collector. I'm currently using an old Harley Muffler but am considering switchhing to a Cone Engineering Reverse Cone. I do understand this may change my jetting again and this also may make this discussion irrelevant to my situation but in the interest of learning, I'm curious.
I had my right cylinder running nice and tan but my left was running a bit rich but the bike rode really nice with it pulling to 10,500 rpms, would reach and maintain 85mph on slightly hilly terrian, and I could feel the "power band" kick in from 7,000 to 9,000 rpms. Keep in mind my set up was Mikuni VM30's running Thunder Products UFO's with a 3.0 Slide per the UFO instructions( only issue with this is the bike would only idle around 1600 rpms, no lower with the idle screws all the way out).
With that on to my left slightly rich left cylinder. Can this issue be resolved with a slightly hotter plug such as the B7ES. I have no issue changing jets, just curious on the hotter plug on one side versus the other. Of Note: I may change out the slides after I put the bike back together. I am thinking of switching to the Paamco Ignition system and I understand its advance works best if idle is set to 1200 rpms. We'll see how the bike runs once I get it back together.
Cheers for any insite. Goat`