TOPIC:

Got a nice PM from an owner whose carbs I just rebuilt. One of the nicer sets I've worked on!

It still pops on deceleration but nowhere near as bad and I'm pretty sure it is just the header making that happen rather than the carbs. I think every bike I have ever owned did that with a header on. Even my (omitted) backfires on decel and its fuel injected. I've read the unburnt fuel detonates in the header after being ejected from the exhaust port. What do you think? I'm not bothered by it in any case, just making sure its normal for these.
In any case its smooth as silk up and down the rev range. No smoke. Cruises nice at any RPM with(out) hitching or stumbling. Starts easy and idles smooth. I'm thrilled as hell so thanks]

The reason for this is usually because over the years of different owners and/or unknown disassembles - The enriching covers, guts and the carbs they were originally set-up on at the factory - get swapped around. They may be identical to look at but they're not. That's the purpose of the "set-screw" in the center of the cover. It is adjusted per carb to set the exact closing point of the piston. On my carbs there is a very small gap at closed position which allows some air to pass. For the sake of this point we just assume the piston closes fully and shuts off the air 100%.
And for what ever it's worth: The richening diaphragm/piston starts to move @8"hg., is 1/4 closed @ 10"hg., 1/2 closed @ 15" hg., 3/4 closed @18"hg. and is fully closed to the set-point @ 22" hg.
So if someone claims they can sync their carbs to 18"hg - They've got a PROBLEM ...................... you can't ! And if you could you'd be getting really shitty MPG/KPL

What exhaust is the guy having? What intake side? Filter or modified? Most people don't pay attention to these taking them for granted, but there is a whole physics science behind it. You can't just swap pipes and even worse, replace them with straight pipes! 6-1 or 6-6, or whatever combination, makes a difference. Louder and back fires are what I hear all day long from Mr. Harley's - bad bad choice. They don't realize the horse power lost. Louder saves lives? Nope. Safe defensive riding does, and the HP to get away from danger when you need it does. Anyho... No idea what the guy has in his bike, but the pipes with all the mufflers and stuff are there to create a pressure barrier, same on the intake side, to balance exchange of gasses, others on the exhaust side. Any distortion will create imbalance, and can result in loss of horse power, unless corrected with carburetor adjustments (jetting, and so on...). That has to be done case by case. Back fire sound to me as too much free way on the outside... Could be just one of the reasons, which I simply wanted to point out. Check the reed valves, blow the exhaust, 30+ years of C02 deposits will disturb the balance as well. Oh wait - a proper spark plug gap? That would change the fire! I'll stop at this, but there is much more to the science of stopping the 'crack in the pipe'! LOL

Am I on my own in actually liking popping & banging on the overrun Hell, my Yamaha MT-01 was actually designed to do that from the outset, but then it's a dirty great V-twin...

Just 'googled' it. Nice looking V2! I think that's what HD tried to accomplish with the Buell? There are differences between 2 and 6 cylinder engines by definition. That HP loss I mentioned is overall academic, who would really feel even a 10 HP loss, unless on a track or a dyno? I'd say enjoy what you like, and crack that beesh!

Won't argue there's a "scieince" involved. That's dealt with at the factory and we get what they engineer. Don't over-think this ! I've had MANY sets of carbs on my own bike in order to set them up. This is done with out an air filter. The road test is done with a filter. I've had three different air-filter systems on my bike over the years. Stock, a filter that utilizes something similar to the upper cover (goes on the carb inlets) and the one I'm runnuning now, "Custom intake and filter" - if you can find it in the forum. Makes no difference in the initiall set -up and I can not discern any difference between the three as far as hwy riding goes with any of these 3 air filter set-ups. The "top-end" jetting can be leaned or richened with the 5-slot needle but my personal experience has proven time and time again that the #3 slot (with a header) is the best setting. I tried leaning (once) by dropping the needle 1 slot ( raising the C-clip) and had a "surge" on the Hwy that required the throttle to be "worked". Went back to the #3 slot ! I like the color of the plugs with this set-up. If anything an adjustment to the c-clip (Lowering it 1 slot) to richen the top end may give some the high end mixture they're looking for. It's up to the plug color to help dictate your choice.
The expalnation for the "popping" stands as written.

I am an idiot, still, when it comes to the KZ1300. NO idea what your are talking about scotch, because I truly have no clue!!! LOL
Saying which, the lille more clue I have in regards to Vmax and engine overall, would the KZ13 has some magical hidden extra properties? I would never doubt. But here it is: any other engine has the exhaust and intake balanced to a pressure which will not get those fumes back the intake hole. There is a bugger reason than noise to the mufflers.