air passages in keihin CA77 carb

FatDog · Post by **FatDog** » Sun Jul 08, 2012 4:47 pm

I finally got my dream project out of my basement.

The gas will not flow through the carburetor while everything is hooked up. if I crack open the the float bowl a hair, the gas begins to flow... tighten it back down... it stops.

Basically to me it reads as a tight/plugged carb... with no where for the air to leave and make room for fuel. Can anyone tell me or point me toward a schematic where i can see what passages may need a pipe cleaner? The carb is mounted to the bike and I'd like to keep it that way. it's awkward on the ca77... getting it on and off... especially with the air filter.

many thanks
Tom

G-Man · Post by **G-Man** » Sun Jul 08, 2012 5:14 pm

The float is there to cut off the fuel when it has reached the right level. If you drop the float bowl the float will also drop and let fuel flow.

What problem are you trying to solve? If you are in any doubt about blockages of the jets you need to take the carb off and clean it properly.

G

pknopp · Post by **pknopp** » Sun Jul 08, 2012 6:05 pm

As G-man notes. If you have a blockage you aren't going to get it clean on the bike or with a pipe cleaner most likely.

I have a cheap ultra-sonic I use. Works great with something like Simple Green.

conbs · Post by **conbs** » Sun Jul 08, 2012 7:11 pm

As said, you will want to take your carb off.

The idle jet is particularly small and I have had a couple that were plugged so tight that I had to use a .010 guitar string to get the varnish out.

If gas flows when you loosen the bowl, it may be your float hanging up on your bowl gasket. They are pretty simple carbs, but everything has to be working or you will have trouble. Good luck.

FatDog · Post by **FatDog** » Sun Jul 08, 2012 11:00 pm

thanks guys,

i already rebuilt the carb... cleaned all the passages and put in new floats, needles, boot gasket, etc. and set the height BUT i actually think you may be right - that the float needle is sticking. Sometimes your brain sticks on something when you start assuming you're already past an issue. I bet a little wiggle will fix everything. Will update soon
Tom

cknight · Post by **cknight** » Mon Jul 09, 2012 4:58 am

Another possibility is that one, or both, floats are bent slightly outward at the bottom, and contacting the float bowl when it's installed. That would prevent the float assembly from freely dropping down to initiate fuel flow. Regards, Chase