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I can prolly hook you up, just need to get to the garage attic and see what I have. Need to move some vehicles & do it when it isn't 115+ degrees up there. More to follow by private message when I see what's what.

Thank you, you are a life saver! As far as I can tell my current carb is in working order, when I spray carb clean in the different passages it seems to come out where it should but I don't have any other ideas left. I don't want to spend a bunch of money testing my theory. I already spent a bunch thinking it was electrical, the CDI because testing pointed to it and coils plugs and wires to rule them out and the pick up coil just because the rest was new. A note on the pick up coil, they only list one for our bikes and the boot points the wrong way where it comes out of the stater cover, down instead of up. I didn't want to spend a ton on carbs to find out that isn't the problem, if it isn't it must be in the engine but I really don't see that being the case.

Just read through the thread and been through a similar problem with my Grandsons Honda VTX 1300 v-twin. it is a 2004 with 4,000 miles and is a beauty and had been sat for years. Cleaned the carb and new plugs and ran good for a few miles then sooted up the plugs and front cylinder cut out. ALWAYS front cyl. going bad changed front coil, checked plug wires resistance. replaced wiring from Ign.Control Module to front and rear coils fired it up and ran on both cylinders, put side panels on bike and seat and got ready to take it out and it wouldn't fire up. Just couldn't believe it. We checked the blade type fuses and found the ignition fuse blown, replaced it and all worked well and is still running strong. The fuse had "blown" but not how a blade fuse normally does. All blade fuses i have seen blown seem to shear across the top of the "U" or upside down "U" actually. This fuse looked like it had started to blow out on one side of the "U"but it still managed to somehow allow enough current to power the coils and as we kept trying to run the bike it allowed the leg to bend but as it did the leg got thinner. The thinner it got the more it got hot and "stretched " apart till it finally broke for good and not even one coil would fire. Then we finally found the culprit. A BAD FUSE, slowly blowing under load. It led me a right old song and dance as we say in England. Maybe just maybe you might be having the same issue. Checking all the connections in the fuse box may help.

It's something to look at, I did check the fuses but didn't actually pull them out.

Hey Ian, good news, I have a complete, unmolested set of carbs I am willing to sell. Your PM box is full, so PM me when you are ready.

Sorry about that, I deleted some.

PM inbound, replied to yours. I could not send a new PM thread, apparently you are over some limit...

I deleted several pages and was still deleting stuff from 07, I had no idea I had so much in there. I want to keep a few of them so I have to be selective but will eventually get rid of most.

How'd you go Ian....you end up having a win
Seems very strange to hear you asking for help 🤔

I haven't been able to get back to it. Was a time I would have thrashed day and night until it was going again. I have been working on my truck and I refurbished and old Rockwell jointer that I started when I was waiting for parts for the bike. I have a set of carbs to go through and try now but haven't had the time to do it. I have had my 64 BMW out a couple times but I really want my SM going again.

Got the 2nd set of carbs gone through and put them on yesterday, No change. Really has me stumped, has to be something that effects only the right side, I really thought I missed something in the original carbs and the 2nd set would clear it up. 150 PSI compression, valves in spec., new CDI, new coils, new crank sensor, new wires and plugs, changed cabs, bypassed harness for power (as test, put back when didn't change),crank sensor (pick up coil) set to new spec ( was already set to that with old sensor too) Can't be intermittent sticking valve as it doesn't vary always acts the same. I might have to take it to Hermy's and see if they can figure it out, I can't believe I am even considering letting anyone else work on one of my bikes. I have never done that before.

FWIW, I doubted it was the carbs. That said, given everything you have done, other than a faulty connector or wire, I don't know...

I know, I didn't think so either but I was at a loss. I had gone through my carbs twice and sprayed gas in the back of the faulty side with no effect and could see it drawing fuel I was just hoping and grabbing at straws. I bypassed the harness so I doubted a faulty wire or connection. I also replaced the entire ignition system so to me it only really left an issue with the right carb. I also used an inline spark tester and I don't lose spark. I will have to get out my power probe and trace the harness to see if I have a broken wire or faulty connection I can detect with the transmitter attachment. This all started when I had to let it sit a season because of my wrist. I have extra carbs besides the pair I bought but not direct replacements.

Man I hate when you have to keep chasing a problem . Sounds like you have done everything I would do so ill throw something out there just for the heck of it. The pick up coil is triggered by two spots on the rotor,stator or whatever they call it. One for the left cylinder and one for the right so maybe the trigger point for the right cylinder is not as efficient or is somehow hindered from translating that magnetic pulse to the igniter.
I am really reaching here and have never run across anything like that before but when everything else is doing what it is supposed to do, that is really the only variable left.

Thank you for the reply Chy, the rotor has very strong Magnetism and I didn't see any physical damage. I thought about a sheared key but that would make the left side not fire right too.I really haven't worked on it lately, too many other things that have to get done and I do have other bikes I can ride. If this was one of my antiques it would have been fixed long ago. Very frustrating.

Ian, have you had any luck recently chasing this issue or have you put it to rest for the Winter? This is one that I'm really interested in since it looks like you have tried every trick we have learned about these bikes to resolve this problem.

I have been doing other things that I have to do. My shop has an 8N tractor project in it that I reseated the valves and new carb to get it running. I got it with a blown head gasket. The main tractor is about 1/2 painted, everything works on it now. I also have my hardtail project on the lift in there. Mt 2500 Chevy is blocking the door with no transmission in it or gas tank. I took that apart then broke my wrist. Then this summer I spent catching up on things I had to get done that I couldn't do while my wrist was healing. My boss/friend gave my an 86 Dodge 250 Royal pick up and I spent some time on that so I could drive it. Junked to us for a blown engine and he gave me another 360 that I pulled out of a dump truck. Then when I went to swap engines I took the radiator cap off to start draining the coolant and noticed the rubber gaskets were gone so I replaced that and started driving it. It had a minor ignition issue that I fixed too. It ran OK but wanted to stall at idle. I bought an HEI distributor for it but found out it fit but I couldn't turn it to set the timing without cutting away part of the intake manifold. Turned out the gaps were wrong on the pick ups so I set them and been driving it ever since. I only got the HEI because Dodge in those days use the antiquated ballast resistor set up and the ignition modules were not very good. I may have HEI in my future. The truck in pretty clean inside and out no rust except above one rear wheel and has cap and bed liner. I want to clean the frame of the chevy before I put the tranny and gas tank back in. That truck isn't rotted either, it's a 96. Sorry for the long reply but just got logged back in after the computer crash.

I am late to the party on this, but reading through what all has been done and checked, not much left but a couple things.

reading your story, it all pointed to the ignition pickup, I was surprised that changing that did not resolve the problem. However, I have been down that road before and found that my replacement (new) pickup sensor did not work either, it can be checked with the multimeter, values in the manual. I finally threw an old pickup sensor off a running bike on there and it fired right up.

otherwise, the main grounding at the back of the engine case should be checked. Take it off, clean and sand and reassemble. It is it a great location for unseen corrosion.

this is a long shot, you said that compression is good, for how long? does it hold for a long time? or bleed over a few minutes?

Holds quite a while.I have not checked that ground.