KZ440 surging idle after reinstalling carbs

Hey all,

Been working on my little '81 KZ440D for the past few weeks, slowly turning the bucket of rust into something not-so-unsightly. Anyways, it ran perfectly until today. I pulled the pipes to clean them up, and reinstalled. I took the carbs off to get around the engine and do some cleanup, and in the process, sprayed them down with carb cleaner and wiped off all the dirt. Bolted everything back together, reinstalled, and now when I fire it up and put the choke on, it idles around 4,000... when I turn the choke off, it surges up to 3,000, hangs for half a second then drops back down to 1,100, where it then shoots back up to 3K and then back down. Over and over again. Ran it around the block anyways, it had hardly any power... would pull a bit if I clutched it and hit 4,000-ish, but sputtered something awful. It backfired a few times when slowing down, and then just stalled... I coasted back up into the driveway. Now it'll crank all day and sputter a bit, but won't fire.

Noticed some cracking around the intake boots - this could cause a vacuum problem which could be an issue, yes? Had the plugs out before pulling out the carbs - both were tan. Now after this, the left plug is jet black and fouled something awful. Figured I'd get new plugs anyways, but want to nip this in the bud before I bother, otherwise I'm assuming it's just going to happen again. Any ideas?

I've torn apart carbs on a couple of other scoots so I'm not afraid to give it the go-ahead. I'm guessing it's probably going to be happening

Hi SSMD50,

Look toward intake leaks between the carbs and the head. WD40 will tell the tale but will take some cleanup afterward. Basically just spray the liquid at the suspected leak to see if the idle evens out.

Bill