I find the claim difficult to believe. Honda used the same style carbs on the 500 and 550K/F models. The carb differences for the models vary only in the jetting and adjustments among models. They all used the same air filter. Only displacement and exhaust changes were made to the machine's engine characteristics. If what you say were to be believed, then all the differences Honda made to the carb's metering were for naught.
I'm new to this world of carburetor Honda SOHC4's but after doing a bunch of research prior to rebuilding my carbs, not only have I heard it from several classic honda enthusiasts that you shouldnt need to rejet when going with pod filters and different exhaust systems, but my bike is proof. You COULD benefit from going up to a 105 or 107.5 but its purely dependent on what pods/filter of course, what exhaust of course and how worn the carb needles are already. I've found out, stock bikes end up running rich after carb parts wear. My particular combination of pod filters and 4-into-1 exhaust runs great with the new, stock size 38/100 K&L jets, idle screw backed out 1-1/4 turn and floats set to 22mm... period. I've also JUST put over 50 miles on this combination so I realize I have a "break-in" period to go through... we'll see how well it stays.
I predict we'll find out that the Butt dyno you are using, is not quite as accurate as the ones Honda used to tune the bikes with changes to carb fuel metering. There is also the fuel economy aspect to use as comparison for properly tuned, but not reported. Got any Dyno printouts to back your claim? Did you have any seat time on the same bike in the stock configuration, with which to compare against? Even if your bike runs well, how can you claim it runs as well or better than stock?
Agreed, butt dyno's are deceiving. SOunds and throttle response trick the butt into thinking a bike is or could be running better/faster/weaker/etc.. Yes I have had seat time in a stock configured 75 CB550K (exact same bike as mine practically) in perfect running order and my bike runs at least as well. I NEVER claimed it ran better than stock but I can say with a fair amount of certainty that it runs as well as stock and it does so looking better, sounding better and "feeling" better than stock.
Another point I would like to make is that you replaced Honda parts inside the carbs, with ones from a different manufacturer. How do you know the parts specs, dimensions were the same? How do you know it wasn't a happy coincidence that the part changes didn't happen to be just what you needed to have your engine run well? (Assuming it does run well, make the same power, and have the same fuel efficiency as the stock bike.) Were the jets really the same diameter as stock, or just stamped that way? Did the K&L kit have replacement emulsion tubes? If so, did they have the same air bleed hole placement and size as the stock ones? Was the throttle valve orifice the same or larger than stock?
Seriously??? Is this just in the spirit of debate??? Youre suggesting I just got lucky with improperly stamped jets!? Or youre questioning whether the stock rebuild carb kits from K&L might be some magical kit that took into consideration that I was going to run pod filters and a 4-into-1 exhaust so they just stamped the jets 38 and 100 but secretly knew what size to make them so they'd run my bike better?... or that they would just stamp the stock numbers on larger jets to give you a rich mixture for the fun of it? I retained the original stock HONDA emulsion tubes and needles. From what I've been told, that is the best thing to do when rebuilding, unless theyre damaged or corroded or something, especially when running pod filters and free flowing exhaust combinations, as the wear on these parts can contribute to a slightly richer mixture.
And whats this about fuel efficiency? LOL... just because it has the same size jets does not mean it will have the same fuel efficiency, documented or undocumented. Fuel efficiency is dependent on too many variables. Even if you were to run 2 engines side by side on a dyno at the same load and at the same rpm, both with stock jetting, one with stock filter and exhaust and the other with pod filters and free flowing exhaust, you'd never have identical fuel efficiency. Throw that comparison in the garbage. I either get 50mpg or I dont LOL.
Further, why would you assume a 35mm pod from all manufacturers would have the same air flow/ restriction characteristics? Or, that they would be similar to what the stock air filter arrangement provided?
I'm thinking your pure proof has some variables in it.
Of COURSE my pure proof has variables LOL... My bike is a 76... his is a 78! I know my particular cocktail of parts and jetting is NOT going to be the same on my 76 as his 78 for the same outcome. I just used my experience for comparison because he said "As you would expect, when I put everything together I had a beautiful bike that ran like crap". My argument was that it isnt always "as expected".
I never said my 35mm pod filters had the same flow characteristics as any other filter or have similarities to a stock filter arrangement BUT I had my bike running great with NO filters... only the open carb inlet runners. So, with that being said, I still stand by my belief that you dont have to rejet, at least a 76 CB550K, when going with ANY pod filter combined with at least MY free flowing exhaust.
I do agree these Hondas are lovely, though.
Cheers,
Agreed