Honda VLX600

[Bassman12]

I have a 2002 Honda VLX600. I hadn’t ridden it in 8 months so the carb gummed up. I pulled it apart and cleaned it up. Over the years I’ve done this several times and each cleaning allowed the bike to run perfect. This last time it has a nasty sputter and backfire off idle. Once I get to cruise it runs fine. Im sure the carb insides are spotless. I even went as far a running Fishing line thru all the little ports for the pilot system. ) Even though they looked fine I’ve replace the pilot adjustment screw pilot needle, pilot jet and deceleration air control valve (which seems to be tied into the pilot system by enriching the mixture during deceleration). I can see the accelerator pump is working and squirting in a healthy amount of fuel and the carb’s slide seems to work (go up and down ) with throttle position. I’ve checked the float level and I’ve changed the plugs, the 2 coils seems to ohm out fine and electrically appear identical. All the4 high voltage wires seem to also ohm out identical. I’ve pressurized the intake system without the carb on looking for air leaks (no obvious leaks ).
I’ve scoped the signal coming from the crank sender and out of the ignition module for both cylinders. Both look good although the amplitude of one is 20% less than the amplitude of the other. I might expect this as it idles fine during the measurement
I does seem to run better when the choke is on (less sputter) which tells me is running lean without the choke. The nominal position of the pilot adjustment screw is three turns and it also seems to run better with 5-6 turns but that means the pilot screw will almost fall off the carb. I tried increasing pilot jet from the stock 45 to 48 and 55 and trying the adjustment screw in all kinds of positions. No change.
My next thought is to hook up a timing light while I riding the bike and look for missing ignition pulses while under load (acceleration) because I really cant carry my oscilloscope with me on the bike.
Anyone have any other thoughts? New carbs cost ~ $400 and I hate to take the risk that it’s something else.

[pchast]

Clean it again?

sounds like some of those passages may still be plugged.
did you use some fish line to check them all out?

[Bassman12]

yes I used fish line and I even drilled out some of the factory sealed plugs in the carb so I could view the internal passages. Clean as a whissel.

[pchast]

sorry for the silly question but then...

Hmm, How did you seal them back up?

[Bassman12]

Good question. I had an aluminum plug made with a stepped diameter as close as the stock plug as I could detect and sealed it with RTV.

[Bassman12]

I finally got it. I had been trouble shooting the carb with the air cleaner off. This allowed for a lean condition.