Mikuni VM26 Float Overflow

I've taken the float bowls out and done my best at cleaning these a number of times. I have removed the float needles to make sure they appear okay (I'm not very experienced in carbs so I'm just guessing at their condition, but they seem okay). I have checked the action of the floats and the float needle with the bowls removed. However, every time I put them back on the bike and let them fill they overflow. It's never all of them, usually just one or two, but it's never consistent either. They are draining out of the overflow spigots on the bottom of the bowls.

Is there something I'm missing? Like I said, I'm a bit of a noob with carburetors, so don't skip the obvious for me.

Bike is a 76 Kz900-A4 and the carbs are stock - no changes.

Also, I need to rejet the bike as it still has the stock 115 main and I now have pod filters and the bike has had an aftermarket exhaust since before I got it. Any suggestions? The pods are EMGO from Z1 Enterprises - I have no clue on the exhaust manufacturer, but it is a 4-to-2 with cylinders 1 and 2 sharing and 3 and 4 sharing. The rest of the bike is bone stock and will most likely remain that way until I bury it with me.

Is it possible that the float level is just too high?

That's sure possible but doubtful. There's no way really the needle/seat "seems OK". They either seal and no overflow or they leak and you get overflow. They are really sensitive to dirt too, so be sure no dirt is flowing. If no dirt, replace the needles/seats to eliminate this headache.

Anyone know where I can get the seat and needle? Z1 Enterprises looks to have the needles, but I only sells the seats (from what I can find) in a carb rebuild kit - which is more than I think I need right now.

"Temporarily out of stock",
BUT...these kits do have both.

Check with Jeff personally though...you never know what he can get you.


www.z1enterprises.com/detail.aspx?ID=43

i buy a LOT from z-1, and have been happy with everything...but emgos from anywhere are second rate junk ..i bought a set online from ebay and they are junk...doesnt take much to seperate the rubbers from
the chrome parts...they look cool, but k and n s are a better choice...i cleaned and re-oiled the well used k and n s that came with my bike ...just my .02

DoubleDub wrote:

...don't skip the obvious... bike is bone stock....

If not already installed, should run an inline fuel filter (aftermarket accessory) on each fuel line from the petcock.

Inline fuel filters are inexpensive, and carried by Z1E.

Good Luck!

Yeah - I'm pretty sure my problems are because there wasn't a filter. There is one now. I'm going to take them back apart and try to blow them out with some compressed air and see if that helps.

I agree about the EMGO's. I'm actually thinking I'll go back to the stock airbox once I can get a new air filter and replacement pipes from the carbs to the airbox. I'm thinking now that they are definitely temporary.

DoubleDub wrote:

... wasn't a filter. There is one now....

Thinking the KZ900-A4 carbs have two fuel pipe intakes via lines from the two petcock outlet nipples. Same as KZ900-B1(LTD)carbs. Which of course requires two inline filters (one on each fuel line).

There's a fuel pipe intake between carbs 1 and 2 (fed by a fuel line from one petcock outlet nipple), and another fuel pipe intake between carbs 3 and 4 (fed by a second fuel line from the other petcock outlet nipple).

Probably already known -- just being sure.

Good Luck!

Si. There's an aftermarket petcock on the fuel tank with a single output so I actually have a single filter and a T splitting it out. I've also utilized the wonderful photos from wgcarbs - somewhere I had seen instructions saying that the float bowl vents were vacuum ports and should be connected together - amazing how much faster things fill up from dry with them disconnected from each other!

1976 KZ900 oem routing of carb vent tubes with open ends held in clips molded into top of air filter box lid.

[Click on image for larger view]

It looks like that might be the OEM hose routing as it came from the factory but I think it is insane to have open hoses which might potentially carry gas sitting directly over the battery. Just strikes me that if the bike tipped over and gas poured out the vent tubes WHICH IT WILL repeat WILL DO pouring onto the bike's electrical system. I would much prefer to have vent hoses going back over the swingarm. In the event gas pukes, it will not get on either a hot engine or the electrical system. In fact, if the bike went over with you on it, your crotch would get soaked with gas. Nuff said...