Keihin Butterfly..... rubber plug

[Sonny S.]

There is a rubber plug in the slow jet feed. It appears the jet gets fuel from a small hole in the main jet feed.
Ever run one without the rubber plug ?

[Lew]

Not for very long........

[lasmittys1]

There is a rubber plug in the slow jet feed. It appears the jet gets fuel from a small hole in the main jet feed.
Ever run one without the rubber plug ?

The main jet flow would no longer be metered because the fuel would go up the unplugged hole and bypass the main jet.

[Sonny S.]

Interesting..... I would figure the jets themselves are what actually does the metering. A slow jet will only pull so much fuel, and shouldn't it still leave plenty for the main ?
Looks like float ajustment is pretty critical. Could definitly affect the slow jet being as it's pulling fuel from up on the main feed.
Obviously I'm green on theses carbs.
I knew I liked my CV's for a reason

[lasmittys1]

Interesting..... I would figure the jets themselves are what actually does the metering. A slow jet will only pull so much fuel, and shouldn't it still leave plenty for the main ?


If you look at the carb closely you will see that ,with the plug in, the fuel goes through the main jet and then through the bypass hole then feeds the low speed jet. the bypass hole is drilled above the main jet. when the plug is removed, the fuel goes up the low speed tower through the bypass hole and past the main jet.

[Sonny S.]

Thanks !

Had the carb last week, don't have it now.... will have it tomorrow ..lol
I rebuilt it for a guy, bikes been sitting 2 years... new float, needle, pump & o-rings. Guy said it's coughing through the carb at idle. I don't have the bike.
I think the fuel level might need raised.

[MMOCGuy]

One ofthe problems with those carbs is that they cough through the carb at idle. His is no different. I've found that running the idle/air mixture a little on the rich side helps. The original carbs from the factory had a plastic stop on the idle/air mixture screw that only allowed about a 1/4 turn. You can eliminate that limiter by either removing it by prying it off the top of the screw or you can purchase an after market idle/air adjusting screw that has a larger head on it making it easier to turn.

Hope this helps.

Norm.

[ST40]

One ofthe problems with those carbs is that they cough through the carb at idle. His is no different. I've found that running the idle/air mixture a little on the rich side helps. The original carbs from the factory had a plastic stop on the idle/air mixture screw that only allowed about a 1/4 turn. You can eliminate that limiter by either removing it by prying it off the top of the screw or you can purchase an after market idle/air adjusting screw that has a larger head on it making it easier to turn.

Hope this helps.

Norm.

I'm working on a friends Shovel with one of these carbs and noticed the coughing problem also.  I'm waiting on a few parts, but I figured it had a lean condition at idle also.   First I am going to adjust the screw.  If that doesn't do it, I'll adjust the float slightly.  Surely some improvement is possible.       Marty

[Sonny S.]

I have the best fix for those carbs he just did'nt want to go that route   

[Sonny S.]

Well, it gets worse.

The dude fired up the bike,  oil started coming outta both pipes, and the stator cought fire at the connection.
Said he kicked it over slow before trying to start it and it hung up a few times.....with the plugs out. Maybe the rings broke ?

Crazy thing is I might end up buying the bike..... gonna look at it tomorrow.
84 Low Rider

[Hillside Motorcycle]

Bet that did not impress him!

[Sonny S.]

What ?