Choke applied - my butt!

I have a '78 KZ10002A2, which I purchased from the original owner back in '82. For the first time, I replaced leaking rubber gaskets / seals, along with painting the gas tank, new seat upholstery, Dyna S electronic ignition / coils / wires, fresh seals / oil in forks, cleaned the carbs, new tires, etc - everything to stock form. No valve adjustment, nor did I check (my error – next time). 17,000 miles on bike.

The seat is still off the bike as I have not finished it, but the rest of the bike was ready for a test run. I noticed that when I sat down on the bike's frame the rpm's would go from idle to 3500. I stand up - the rpm's return to idle. Strange but onto the test ride!

Ran well slightly off idle and after a couple of hundred feet, I cracked the throttle open - engine died. Pushed it back into the garage and attempted the same again. Stupid me - I found out that my butt (when seated) was covering the intake ports on the stock air inlet.

Why did the engine's rpm increase when I sat down on the fresh air intake? Prior to the test run, I turned the pilot screw out 1 turn on the stock VM26 carbs (carbs are not synchronized). I thought that the carbs were running lean so I increased the pilot screws to 1 ¼ turns out to richen the air / fuel mixture. From here I adjusted the individual pilot screws to listen to an increase in idle.

When I cleaned the carbs, I only replaced the top / bottom gaskets.

Next test run, after removing the stock air inlet section, the bike ran well from off idle to high rpm.

What should I do next and why did the idle increase when the engine was being ‘choked’?

the idle increases because covering the air inlet increases the vaccum and the engine has no option but to pull more gas from the float bowls into the engine.

ok i can see where your coming from with the engine pulling in more fuel, but wouldnt the engine die because of the lack of air and the extra fuel? should flood itself i would think, not run higher rpms. with the extra fuel, it has to have extra air to compensate. might be way off here as carbs are not my thing, but that doesnt make sense to me.