Mikuni tm32 overflow issues

[oldluke]

Hey dotheton. this is my first post!
I own a 77 Kawasaki kz400 and I'm having carburetor issues.
I've replaced the factory carbs with mikuni Tm32.
Both carbs are overflowing 30 seconds to a minute after the fuel line is opened.
I've tried changing my float height and changing my needle jet height and a combination of both to reduce the amount of fuel allowed into the carbs.
Still I get overflow. The carbs were customized to the size of my engine by sudco and no modifications have been made by myself.
The float needle moves correctly and corresponds to the floats.
Has anyone else had this issue with mikuni Carburetors?
Please advise! Thank you!

-luke

 

[Big R]

I've never worked on a TM carb, but try this first: drain the bowls, remove the floats and float needles (since they will fall out anyway). Then push both float needles in and hold them there. Turn the gas on at the petcock and see if gas runs down your fingers.

 

[DesertKZ]

Are they new floats? Double check that they're not sinking.

 

[Mr.B]

How do you set the floats on the tm32?

 

[Autotek]

I had the exact same issue with one of mine but it stopped on its own? I used them on a 76 KZ400. Only one of mine was doing it and I cant tell you why it it stopped. It has in fact started doing it again a little. Mine doesnt flow more of a really slow drip. I adjusted both floats down a bit when I first noticed it but I have no idea why it stopped. Perhaps it is a problem with these carbs. Did you buy them from DCC? I also had to lower the jet size to around 150 because it would bogg badly with the 185s. Sound familer?

 

[oldluke]

@autotek

Sounds familiar. I can't leave the gas on for more than 30 seonds without overflow. I've tried disconnecting overflow hoses adjusting float height, and ajusting the needle jet. Tried starting it yesterday and got a hint of backfire. Considering purchasing new float needles to try and solve the issue. I bought the carburetors from Sudco. Everything is factory and the floats are not sinking. A buddy of mine mentioned that the carbs are built for two stroke engines? Not sure how that affects my four stroke. Any more information would be helpful! Thank you!

 

[oldluke]

@Big Rich

Not sure if that applies with my carburetors, the bowls are filled with fuel from the bottom up. Thanks for the support!

 

[oldluke]

A friends of mine had heard rumors of shaving this piece down for four stroke engines. Any confirmation of work like this? Thanks again.

 

[Big R]

Carbs for 2 stoke engines are just tuned for different air/gas flow characteristics - none of which would make the carbs flood. And you would just need the proper parts from Sudco to make them work for you.

I think you are referring to the jet needle and needle jet in that pic? Those are some of the parts that would need swapped - not shaved.

 

[Autotek]

I assumed that i had trash at the float bowl needle and it worked it way out. Now Im wondering if these carbs have a design flaw. Brand new carbs should not leak, and It is extremely unlikely that it is trash in my case. I cleaned the shit out of the tank ran all new lines and used a filter. Def sounds as if your case is worse than mine. Are yours right and left, (a match set) or two lefts. My leaker is the left side.

 

[Autotek]

Side note, I made custom linkage for the choke levers...

 

[550 Okie]

Thought I would help old luke out with some more pictures of the carbs since his bike is at my place currently. They are flatside tm32's and look to be two lefties.

I've been trying to look up flooding issues on these and came across a post on the SOHC forum where someone was talking about shaving down the needle shaft (as shown in oldluke's photo). I thought that made sense because wouldn't the height of the shaft keep the needle from going down far enough to stop the flow of fuel? This is my first time working with mikuni carbs so it's a whole new world for me.

 

[teazer]

The carbs should not flood (obviously) so something is wrong. They have two independent floats and my guess is that something was assembled wrongly by SUDCO. Hard to do, but possible.

The needle has nothing to do with flooding/dripping and any one that says so is itching for a fight. I can't remember where that expression came from, but never mind. Leave that as a silly internet myth.

Independent floats can be adjusted by tweaking the brass tang/lever that both float pins touch.

As Big Rich pointed out earlier, 2 strokes and 4 strokes need different fuel slopes and different atomization. For example, piston ported 2 strokes are rich at lower revs, so need a leaner bottom end jetting and work best with a Primary type needle jet. 4 strokes tend to need a different fuel slope and use Bleed type needle jets, smaller air jets and shorter fuel nozzles.

While the TM was designed for MX engines, it can be made to work OK on a street 4 stroke.

Do you have a list of ALL the jets in your carbs?

But first off remove the carbs and drop the float bowls and see what's going on in there. Could be the float arm is bent or hooked under a float.

 

[Autotek]

We seem to have the same issue but mine are obviously not flat slides. I have already done what Teaser suggest you try to the float bowls and mine work correctly 95% of the time. Perhaps I need a bit more bend on the left side. It makes the most sense. BTW Teaser, I am on my best behavior, I have seen what happens to people who are itchin around here! Good luck and keep us posted, I am interested to hear how it turns out.

 

[teazer]

When I sat down to answer the thread, there were several posters with issues, so hopefully it made some sense to someone. 8)

 

[oldluke]

@autotek

Both of my carburetors are lefts. I'm assuming they are both faulty. In the process of contacting Sudco. Will post results when and if more information is available. Thanks everyone!

-Luke

 

[teazer]

I have never heard of two faulty float valves. Doesn't mean it doesn't happen, but it's really odd. How were the float levels adjusted?