tk 22 known casting issues?

undefined Hey guys,
Been a while since i've been on here, my 81 gpz has been in the shop for months due to engine issues, got that all checked out (it was the timing). However now my mechanic is telling me that the tk22 carbs are leaking into the cylinder due to "casting issues". Is this a known issue with these carbs? He's telling me to shell out a lot of dough for mikuni's. How detrimental is this issue for my engine i.e diluting the oil? thanks.

Turn gas off when you stop.
 

That's what i thought too however he keeps pushing me to buy the mikunis or something similar, saying that no matter what he does to the jets it'll always be rich due to this casting issue. 

I've been through many sets of these carbs and have never seen any "casting issues".  Can he be more specific?

The float valve assembly can be replaced as a unit and is sealed with a fiber washer.  That fiber washer should be able to seal most imperfections that typically show up.

Do you have a photo of the actual problem?

Also, if the fuel level is high enough to leak into the intake port of the head, then it's also so high that the overflow drains should be pissing out gasoline like crazy.  Is that happening?  If not then the drains are clogged or the problem is not the fuel level...more likely a jetting issue or using jets or needles from a counterfeit Chinese source.  Those are a known cause of overly rich conditions.  

The details can be found on the Tk22 website.
s3.amazonaws.com/gpzweb/TK22mainPage/TK2...TK22rebuildKits.html

s3.amazonaws.com/gpzweb/TK22mainPage/TK2...K22threeNeedles.html

He’s saying that the casting is so porous that it’s absorbing the fuel or something like that and it’s just unmetered fuel I have no idea when it comes to carbs and he’s been rebuilding these types of bikes for 40+ years, drag racing them ect. He’s very knowledgeable so I guess I’m just taking his word for it but I figured Id come on here and get your guys opinion as well. Also saying no mater what he does to the jets it’s just not going to work. Don’t know really what other direction to go with this… IF I go aftermarket, what carbs have the same spacing as the 550 head? 

Sounds like BS to me.  I've rebuilt scads of carbs and the only issues I've ever seen related to the carb body have been corrosion or damage in some way.

There is no simpler or more reliable set of carbs for a Kz550.  Get another set if you think yours are defective, but like i said if the drain system is working properly, they will be pissing gas onto the floor before raw gas goes into the cylinder.  TK castings are generally very good.  If it has some severe pitting or the like, then it is from a condition issue rather than actual manufacturing defect.  You should be able to find replacement bodies on Ebay.

Later TK carbs are CV type and much more of a headache to tune properly.  They will also require modifications to make them fit.

Mikuni or Keihin made a set that would fit, but are generally for racing and might not work too nicely for a street bike.

I have a set of TK22 carbs on my wife's KZ550 LTD.  They work fine but I don't like the stock high idle setup.  Loudhvx has a fix for that on his website.