81 kz 1000 carb issues (I think?)

Okay so this has been a project bike from start to finish, wasn't running when I got it and the following is a list of the things I've had to do to get it running and to get it running better.

rebuilt the carbs
replaced throttle cable
replaced speedo
replaced all front end gaskets (this was a nightmare, and as a side note, it did run fine before this, just had a mild oil leak, hence the change, but as a testament to these bikes, when we opened up the cam head, we found one of the cams was actually in backwards... wtf? But the bike still ran no problem lol)
replaced the chain


Now here is the problem I'm having and I'm assuming it's carb related. My gas consumption really freaking sucks, I've got a 17 litre (4.5) gallon HD tank on there currently, and I'm getting about 150km until it hits reserve (at about 15 litres) which is fairly redonkulas

Some other side symptoms. Getting a lot of back firing, happens when ever I let off the throttle, but always goes away if I engage the clutch.
Start is kind of weird, I usually have to engage the choke, start it, rev it, pop the clutch back in and dial up the idle adjustment so the engine doesn't die out. Then about 10-20 minutes into the ride, I need to dial the idle adjustment back so it's back to 1k otherwise it gradually jumps to 2k 2.5 and wants to idle there

my thought was adjusting the mixture to make it more lean to help the consumption, so I had the pilot screws backed out to only 1.5 turns, didn't seem to make a huge difference
any thoughts? Suggestions? I would really appreciate any comments. I've looked up the stats on the bike, granted it's a 31 year old bike but I should be getting upwards of 200km/tank on the stock (12 litre) tank, so I know something is amiss

Cheers and thanks for the help in advance!

If you have the Mikuni CV carbs, you can't just spray them out with carb cleaner. They have very tiny passages that won't be reached. You have tear them completely down, soak them in carb dip for 24 hours or use an ultrasonic cleaner. Then replace all the o-rings as well. Otherwise, you will achieve the results you are reporting.

To be on the safe side, would examine and sniff-test the oil to determine possible gasoline intrusion into the crankcase.

Good Fortune!

Yup, They're Mikuni's and they were in fact dipped, not sprayed down, then visually examined each one to ensure the passage was clear and I could see through them.

Any other thoughts?

Negative on gasoline in the crank case, checked that one a few times already

Generally high idle after warm means a lean idle circuit. When you blip the throttle and it takes a bit to come back down, it's probably lean. There's some good tuning instructions in the filebase that will help you out with adjustments. Backfiring is also a result of a lean condition on deceleration. Now, backfiring usually means look out people, race bike coming through :woohoo:

Do know if the carbs are CV or mechanical slide? You can't see through the passageways that will be causing problems.

Alan

Good Fortune!

" but as a testament to these bikes, when we opened up the cam head, we found one of the cams was actually in backwards... wtf? But the bike still ran no problem lol)
replaced the chain"
Care to elaborate a bit on this? Backwards? Replaced "Chain", what the cam chain?
What manual are you using?