'84 VT500 Ascot .... can't get it to idle on rear cylinder

**I'm hoping that the mid-'80's Honda ignition system is similar enough that someone here has some insight. Forgive me if this is the wrong forum**

Working on an '84 VT500 Ascot. The bike sat for at least 14 years and I've been through it from stem to stern. Carbs were professionally rebuilt. I have a pretty good carb guy and never have to go behind him.

I can't get the rear cylinder to idle. I suspected a plugged pilot jet circuit. The carbs were professionally rebuilt, but I did run the bike on an IV bottle for a while, so it's possible that there's trash in the slow jet.

Front cylinder/pipe gets hot. Rear cylinder/pipe does not. I'm getting a fat purple spark that will jump a substantial gap. The outer plug WAS gas fouled today, but I've been messing with it and trying to get it to idle on both cylinders. Fresh plug made no difference.
I poured SeaFoam into the carbs and let them sit for 4 hours. Drained it, added gas, no change. I tried to pull the mixture screw, but I can't get it out of the carb body. Wish it was magnetic. No change when turning the mixture screw on that cylinder.

I suspect the slow jet because when I ride the bike there's a BIG rush of power just past 3,000 RPM, once it gets on the needle/main. That cylinder/pipe starts to get a little heat in it then. I'm only riding it on what's in the bowls until the new petcock gets here.

Over the last two days I've pulled the carbs twice. Pulled the main jet, emulsion tube, pilot jet and mixture screw and cleaned all of them and all associated passages. Did a bench sync. Didn't really find anything, to be honest. I am very, very confident at this point that the carbs, jets, and passages are clean.
Still having the same problem. Checked choke operation. Checked fuel level in bowls using the clear tube method...both the same. Ran the bike with air box off and diaphragms/slides are working. If I put my hand over the rear carb, it wants to pick up and I get fuel on my hand. It just acts like it's not getting fuel to the slow circuit on that carb. Checked compression on that cylinder and got over 175 PSI. Fat purple/white spark.
Double checked valve adjustment and operation on that cylinder. All good. I'm stumped.

At this point I'm beginning to suspect the ignitor. Even though I am getting spark when grounding the plug to he head, I'm not sure that it's firing INSIDE the cylinder, or at the correct time.
Can I swap the two ignitor units and see if the problem moves to the front cylinder? Is there a way to test the ignitor? Any other suggestions?

Pics for attention....

 

Can't help you, but a great little bike! My wife bought one in 83 and rode all over Florida, then we moves to CA.

 

I think you answered your own question Scott. The low-speed circuit is clogged so the bike won't run at idle or small throttle openings on the back cylinder. Given it runs well once up on the main jet circuit, I'd say you don't have a spark, airflow or fuel flow problem.

I'd be hauling the carbs out (again) and rechecking that you can squirt carb cleaner through from the bowl end of the low-speed circuit and see it coming out from the fine jets under the butterfly.

But will be a great machine when you have it back and running, certainly looks really sharp.

 

Got it guys! Third time's the charm!
I have to admit, it was a bit of a bonehead move on my part, but suggestions to go ahead and swap pilot jets and confirm jet sizes set me on the right path.
Turns out I was cleaning the FRONT cylinder carb every time! It's easy to get them confused when you pull them, flip them around and turn them upside down on the bench.
Found trash in the pilot jet. On the CORRECT REAR carb! LOL.
Running like it's supposed to now!
New petcock should be here tomorrow and I can (hopefully) wrap it up for good!

 

Sweet bike there, those are just cool, Very Nice example

 

Hello Scott love the headlight cover, what bike did that come from? Makes the whole front end look better.

 

Thanks. It's from an XR650L.

 

My wife had an '83 VT500 (only bike she could get her feet on the ground) and it was a great bike to fool around on. Everybody wanted to ride it (that shouldn't have) and it was up and down more times than a toilet seat! Only thing that got damaged was the clutch lever. She rode it all the way around Florida, Tampa to Canaveral, down to Key West, across the Everglades then up the West coast back to Tampa. Only draw back was the peanut tank, which meant she had to stop twice as much as I did. It met it's demise when #2 son took the rear bumper off a Taurus that turned left in front of him.

Yours looks great, nice job of cleaning her up. We bought it in Toronto then shipped it to California a year later.