#1 carb issue

[AshishNJ]

Having a hard time figuring out this one.
Carbs were complete rebuild and installed in the custom 81 that uses stock airbox but KN filter.
Bike was running fantastic all summer last year.
Carbs were drained and tank had staybil added.
Didn’t get a chance to take her out ( was enjoying the 79)
Until last weekend. Bike starts just fine but idles like crap. High revs also are studdering.

Checked sparks and all 6 have good fire. However, #1 exhaust doesn’t read more than 170 degree where others are around 400 F and rise the longer I keep it idling.
Swapped #6 plug cable to with #1 but problem didn’t move to #6 cylinder.
I was able to remove float bowl and it was full of gas, so that is not an issue. Cleaned main jet, and sprayed carb cleaner to all passages and they look clean.
Next , removed air cut off cover, checked little o ring was in good shape and flat side was facing carb. Again sprayed and made sure passages were clean..
Issue still there.

Please advise.

[Jeff Bennetts]

Is this all taking place with the staybil treated fuel? I know this doesn’t explain only one cylinder acting up but put some fresh fuel in the thing. I had Staybil turn to jelly one time, it was years ago but I just never trusted it again and use the Lucas brand with good results.

[AshishNJ]

Fuel is all new, sorry i forgot to mention that. Old fuel went into lawn mover and that sucker doesn’t care..

[Jeff Bennetts]

[Marten]

I had that problem on my nr1 cylinder. Turned out that the little shim who his between the spring and the oring on the "fuelscrew" was bent.

Also try to turn the fuelscrew out 1 turn (more than the rest) on nr1, if it runs hotter you know there is problem on the idle circuit.

Good luck!

[CBX-tras]

The orifice for the pilot/idle jet is only 0.35mm and easily clogged, regardless of what treatment you use. If you only drained the fuel and didn't run the treated fuel through the carbs THEN run dry, fuel was left in all the jets (capillary action) and over time, solidified.
You MIGHT get by, to squirt carb cleaner through the jet (remove the alternator, float bowl, rubber plug, sand the tip of the "straw" to a point) and squirt.
If that doesn't work, remove the rack and extract the jet. Simple but special tool here with short video:
https://www.kmcarburetor.com/products/h ... moval-tool

[hondaman160mph]

The orifice for the pilot/idle jet is only 0.35mm and easily clogged, regardless of what treatment you use. If you only drained the fuel and didn't run the treated fuel through the carbs THEN run dry, fuel was left in all the jets (capillary action) and over time, solidified.
You MIGHT get by, to squirt carb cleaner through the jet (remove the alternator, float bowl, rubber plug, sand the tip of the "straw" to a point) and squirt.
If that doesn't work, remove the rack and extract the jet. Simple but special tool here with short video:
https://www.kmcarburetor.com/products/h ... moval-tool

After I drain the carbs I close the choke and crank the engine
over briefly to suck out any residual fuel in the idle jets.

[AshishNJ]

The orifice for the pilot/idle jet is only 0.35mm and easily clogged, regardless of what treatment you use. If you only drained the fuel and didn't run the treated fuel through the carbs THEN run dry, fuel was left in all the jets (capillary action) and over time, solidified.
You MIGHT get by, to squirt carb cleaner through the jet (remove the alternator, float bowl, rubber plug, sand the tip of the "straw" to a point) and squirt.
If that doesn't work, remove the rack and extract the jet. Simple but special tool here with short video:
https://www.kmcarburetor.com/products/h ... moval-tool

JR . I don’t have rubber plugs on my carbs. I do have the extraction tool and I will try to first squirt carb cleaner again. Since it is carb #1, is there a way to do it without having to remove the rack from engine (denso alternator is coming off)

[daves79x]

You can get the top and bowl off fairly easily on #1 and 6 while on the bike. Remove the air cut cover and rubber. Blow through the small brass orifice under there - this is the air bleed for the #1 carb idle jet circuit. All the other carbs' air bleeds are under the dome. Then remove the float and needle, blow into the slow jet tower. You will likely open up what's plugging it, since it's not been that long since it worked.

Dave

[AshishNJ]

Thanks Dave.
I removed the top bowl cover as you suggested and was also able to remove the pressed in jet once I removed alternator. Grinder a wire to .34 mm (#80) and cleaned the jet . Sprayed carb cleaner every where and reassembled . Issue is now resolved:). Thanks to everyone here for their input !

[daves79x]

Glad you got it - this is what happens to some stabilized gas (why I DO NOT use stabilizer). If you use non-ethanol (ethanol will do the exact same thing), keep the tank full and drain the carbs for storage, you will rarely have a problem. I had to clean a set of carbs recently that I did only a year ago because they sat for a couple of months with ethanol gas.

Dave

[AshishNJ]

Dave. Funny you say that. These are the carbs you rebuilt. They have been running fantastic. Full tank of gas at storage, petcock off, drain the carbs and run the bike dry . Hopefully that will be it :)

[Larry Zimmer]

Hmmm. What might you have in the line for a filter? Sounding somewhat like something got through into this carb and blocked the jet. If you don't have a good inline filter, I would suggest that. Whichever, happy to hear things got resolved easily overall.

[AshishNJ]

There is a big fat transparent online filter but since you mentioned, I may just change it to a proper and approved fuel filter

[Larry Zimmer]

Gee -- what you have sounds good to me. Don't have a good idea what got into that carb.