BS34s can't get them right.

Greetings, 

I've reached a point where I'm about out of ideas with these carbs. Hoping a fresh mind might point me in a direction I haven't already tried 3 times. 

I've spent hundreds of dollars on the stock set of BS34s on my 82 kz1000 K2.  Some things include.

1. 4 New Diaphrams
2. 4 New carb kits
3. 4 Genuine Mikuni float needles
4. 4 New floats
5. 4 New stock sized jets (PO had jetted way up)

I've also overhauled the fuel petcock, set the floats via clear tube (see attached).  I have also synced the carbs.

The last test it ran great down low, but chattered under WOT, so I pulled and cleaned the carbs, checked the float level again, put in fresh plugs and now the #3 carb pours fuel back into the breather box and onto the ground and it barely runs!

Every time i pull the carbs, it's something different. 

What the heck, are these things cursed? 

On no. 3 you might have something in the needle and seat holding it open.
Did the previous owner change the jet needle and/or drill the slides?


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It’s not uncommon to have the floats stick open when the carbs are dry. I’ve literally had brand new RS carbs piss fuel the first time they got filled. Tappy tap with a screw driver handle and they should close. Either that or you may have debris in your fuel system 

You were correct.   

More junk in the float seat holding it open. I cleaned everything again and added a paper inline filter.  This seems to have cleared things up (for now).

I'll put some miles on it and see if that will keep the junk out of the carbs. 

Thanks
Scott

You're welcome.


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Be sure the filter you installed is for a gravity feed fuel system, such as for a lawn mower.  Many times paper filters have resistance and will restrict fuel flow.

Good point. 

It does exhibit some fuel starvation tendencies under quick load up. 

The paper filter I got was from an auto parts store.  Everything I found in the lawn mower variety was 1/4 and the bike has 5/16 fuel line.

Is there any particular inline filter you would recommend, like a porous brass style that comes in a 5/16?
 

I use THIS  one by edelbrock. Picked it up from my local autozone for right at $15. Expensive yes however I have had zero issues with carbs getting trash in them and it’s also cleanable so you can spray out the brass filter or just buy a replacement and continue to use the housing. 

my only complaint though is the length of the filter, it is quite large to be sticking under the tank however once I found the best way to mount it, I’ve had zero issues out of it. 

I like this one.   golanproducts.com/product-category/filters/super-mini-filters/
It is expensive, but it filters smaller particles than any other filter I have found, and the filter material is washable, so it will last a lifetime. Looks trick, too.

I have one of those Golan filters on my KZ1000. You'd be surprised what makes it through that filter, not worth the price IMO. The 20 micron claim is hilarious since the human eye cannot even see that small - white blood cell is 25 microns! I personally have seen particles with fresh gas in fresh carbs that were around .005-.010" while running that filter.

Since buying the golan filter and realizing it doesn't seem to stop the tiny stuff I changed to relying on the petcock filter only - the way nature intended. Haven't had an issue yet and i have done this on many bikes. Its better to clean your tank out than to put a in-line filter in for long term success. If you need a quick fix a filter can help obviously.