Carb Clean Idle circuit

andrew7dg

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I was hoping that someone had a tip or trick with cleaning the carb

1982 Yamaha xs650
The bike has been sitting for 3 years and unfortunately had ethanol blend fuel in the carbs.

I have taken the carbs off, taken them apart, clean jets, needles bowls. There are wonderful YouTube videos I followed along.

HOWEVER

No fuel on idle
I have taken some starting fluid and started it up and kept it running
The starting fluid was to check if it was a carb or ignition/timing problem and it starts right up and runs just well on the starting fluid

And in upper RPMs will stay running.
however falls flat on idle

so this tells me the idle circuit in the carb is still gummed up somewhere?

This is the 3 or 4 time the carbs have been off the bike. Looking for advice on what/where/how to clean the carbs.

I did take the caps off the air/fuel mixture screws and put some carb cleaner down them. Reinstalled the screws backing them off 3 turns?

or maybe something else I should be looking at?

Thanks for the advice and help!
 
Yes, the fuel/air mix from the pilot jet travels into the main carb bore through a small passageway. It enters into the main bore through 3 tiny holes along the top of the bore around where the butterfly plate closes. It also branches off and feeds the mix screw on it's way to those 3 holes .....

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Sounds like that passageway or some of the small holes are plugged. It all must be clean and clear. To do a proper cleaning, you will need to remove the pilot jet and the mix screw along with it's associated parts (spring, little washer, o-ring). Then, spray some carb cleaner down into the pilot jet hole and blow it through with compressed air. Block off the outside mix screw hole while doing this. Watch for it to come out those 3 little holes and the little mix screw outlet hole. If you block off that little outlet hole too, all the air pressure and cleaner will be directed out of just the other 3 little holes. Block off those 3 little holes and all the pressure will be directed just out the mix screw little hole. Spray cleaner in the outside mix screw hole, block off all 4 little holes in the bore, and cleaner with air pressure will "back flush" the circuit out the pilot jet hole. So, you can flush the circuit out from 2 different directions and direct the cleaner and air pressure out different holes. Doing all this, you should be able to get it cleared out.
 
Awesome response! Very helpful

I will charge up the air compressor and arm the carb cleaner and get back to you how this works
 
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