Carb Float not working???

I've got a 1982 Seca 750 whose carburetor is going to church... The carbs are now zestfully clean. I have new float needles and valve seats. I did a dry float set of 17 mm for each float and then set the carbs on my homemade rack on my bench to check the wet float setting. All the float levels showed to be about 6 mm below the carb body ( I know the correct level is 2-4 mm). But as I continued to observe the levels, the level in carb #3 started to rise. It rose past the carb body and spilled out through the fuel jets. So I drained the carb, swapped the float needles in 3 and 4 and reassembled. Now the #4 carb overflows. So my conclusion is that there is something wrong with the float needle.

I examined the float needle under a magnifying glass for 5 minutes - compared the "broken one" against the "good one" and I can't see any defects in the broken one.

In searching the forums, I came across a post written in 2012 where member Tabaka45 seems to have a similar problem and fixed it by polishing the float valve with 2000 grit wet/dry sand paper.

I'm inclined to try the sand paper option - or maybe just buy some more float valves and start over....

Have any of you had a similar problem? Any advice or suggestions?

Thanks,
-Rustee Gold
1982 Seca xj750

 

Hitachi carbs?
My memory (careful) was 17.5mm for a dry... but either way 6mm on wet is way too low.
Could have a float that is hanging up (actually down) but really shouldn't follow the needle to #4.
Someone brought up a good point not too long ago - if the tang for the float is bent too far (the 'stop' tang - not the float needle tang), it is possible that when the float drops it is dropping too far and the needle is allowed to get cocked and may lock-up as the float rises.

I recently had an issue with gas in my oil - which as far as I know can only come from a float needle(s) not sealing. It was recommended to remove the needle AND seat and use some toothpaste and lap the two piece together... not really lap but spin them against each other to take down any burr on the new needle seat.... I ass-u-me (in my situation that the new solid brass needle and seats were too crispy new (could see a light witness mark on needles) that the edge of the seat needed the sharp edge burnished down a bit. My carbs are back on the bike and so far everything appears to be good -

So I guess what I am really saying is that polishing up a new float needle is only half of what might need to be polished/ burnished.

 

I know it is a stupid question, but are you sure the float is not in upside down???? Ask me how I know.........

 

where did you get them, i understand there are some that just don't work

 

Thanks for the replies.

I tried polishing the valve needle but it made no difference.

StumpLifter - I have rubber valve tips so I won't be able to use the toothpaste idea to do any lapping.

Plug - yeah... the floats are right side up... however I too have put them in upside down in the past...:-(

Polock - I believe the rebuild kits were bought on ebay - originated in Taiwan (link here) The kits were purchased by the previous owner who could not get the bike to run properly... When I opened the carbs, I could see why - the PO had the floats set at the wrong height and had put in oversized fuel jets and swapped the compensator jets with the air pilot jets... it was a mess inside the carbs - so I put stock jets back in the correct places and reset the floats and re-cleaned the carbs. Now - based on your observation that "some just don't work" I have ordered 4 sets of K&L valve needles and seats - should be here in a few days. We'll see what happens when I get those installed.

Rustee

 

Those aren't going to work either..........

 

Chacal would be one to know if they will work or not. In the future, just order from him, since he didn't want to do self promotion.

 

Please elaborate so I can learn. Why do you say that the K&L needle valves won't work? While I was crawling through the forums I kept reading about all the success that other members had with K&L.