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Honda Bf90a carb rebuilding

M

Matata

New member
Im currently dismantling ,with a view to cleaning , the four carbs on the above motor. I have the bowls off and there was no obvious debris in the bowl. I have removed the end cap to remove the low and high speed emulsion tubes. But I cannot get the emulsion tubes to come out. The low speed tube has an oring at the end of it and I can withdraw it slightly but no more. I was under the impression it would simply fall out ,been kept in by the bottom cover screw.What is keeping the tubes in? Any suggestions would be most appreciated? Nik
 
Look in the throttle bore. The "jet set" protrudes up from the fuel bowl reservoir into the venturi and then pushes into the upper part of the body. It is held there by a small Oring.

Remove it by using a slot end, pocket screwdriver inserted between the top of the venturi and a small "lip" on the end of the jet tube. Give the screwdriver a GENTLE twist and it should pop loose as you break the hold of the tiny Oring.

Good luck.
 
Thanks for that. How do I get the big/fatter emulsion tube out? I gave it a tug and it wasn't keen to move so I left it .Nik
 
Well, like you said, it should fall out. But it's probably hung up on a burr or something on the jet set tube. I figured if you got the jet set out (which you have to do for a proper cleaning) you could see where the emulsion tube is hung up.

Good luck.
 
Just spent the day in the workshop. Steeped the entire card (with bowl off) in a warm ultrasonic bath for 40 mins. That freed off the emulsion tubes.It was the outer bigger one that I had difficulty moving. They eventually fell out. Honda do an o-ring kit for the rebuild which makes life easy but cleaning all the jets/emulsion tubes and fine holes took me 2 hrs per carb. Rebuilding them was a 15 min job. Hope this helps someone! Nik
 
I've rebuilt many, many Honda carbs and not once do I recall having any difficulty whatsoever getting the emulsion tube to slide off of the jet set tube.

I guess I was very lucky or you were very unlucky.
Either way, thanks for the update and the solution as to what needs to be done when the "sticky" happens. The ultra-sonic cleaner is a much better way to go so as to not damage the tubes by forcing them apart.
 
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