Quote from: T Legg on February 26, 2026, 01:45:37 PMIt could be a bad diode in the diode block #27 on the factory manual schematic.The kickstand relay contacts when closed ground out the ignition control and prevents the spark plugs from firing. When the kickstand is up it closes the switch and gives the kickstand relay coil a path to ground energizing the coil and causing the relay contacts to open up ungrounding the ignition module and allows spark. There is a second path to ground for the kickstand relay coil that goes through a diode to the nuetral switch to ground. If that diode goes out then the only way to ground for the kickstand relay is through the kickstand switch.

You may be onto something.  I'm looking through the wiring diagram and circuit diagram and if one of 2 the diodes that supply current to the neutral switch failed open (no current flow), it might explain what I am seeing.  I'll need to pull that diode block and test it with the wiring diagram.  Good thought.  I'm away from home at this time and returning in a week.  I'll report back. 

Quote from: 86FJNJ on Yesterday at 07:15:46 AMWhat is the ambient temperature? I had tuned my FJ in summertime and it ran perfect but when I started riding into the fall as it got colder out the 50F morning starts were difficult and I had a hanging idle that generally went away when the bike and day warmed up. I suspect it wasn't getting enough fuel with the colder ambient temps because I know it was set perfect when it was hot out.

Did you recently may any other modifications like air filter or exhaust?

The heated garage is 60f, outside was 24f. We started the bike with the door closed (over 2k square feet in the garage bay so this isn't immediately unsafe) And after 5 minutes opened the garage door. The smoothness of the response to the throttle improved as it warmed up, but the RPM flux and slow drop persisted the entire time.

No Mods to exhaust, P.O. put in a washable air filter, however I put in the filter I got from Partzilla, which should be OEM.

Quote from: red on February 26, 2026, 11:50:48 PM

Quote from: Warp84 on February 26, 2026, 08:52:49 PMTrying to dial in the Carbs on my 84 1100 and been having issues getting it smoothed out.
We tried doing a leak test at the intake manifold and the vacuum nipples but couldn't locate one. Despite that, I still think part of the problem is a vacuum leak on the intake manifold. But I would like help sorting out all the issues so I can finally get this old girl back on the road for this riding season.

Warp 84,
To find a vacuum leak, use aerosol spray-can ether (starting fluid). With the engine running, spray a little on each part of the intake system in turn. If spraying any one place causes a change in RPM (up or down), you just sprayed the vacuum leak place. Repair as needed. HTH.   

We tried that but I'll give it another go incase we missed a spot.

What is the ambient temperature? I had tuned my FJ in summertime and it ran perfect but when I started riding into the fall as it got colder out the 50F morning starts were difficult and I had a hanging idle that generally went away when the bike and day warmed up. I suspect it wasn't getting enough fuel with the colder ambient temps because I know it was set perfect when it was hot out.

Did you recently may any other modifications like air filter or exhaust?

Quote from: Warp84 on February 26, 2026, 08:52:49 PMWhen running, the bike responses quickly to throttle, but is showing other issues. When on the centerstand and holding the throttle in place, the RPM's will fluctuate up and down by 500-1000 RPM. Sometimes the fluctuation is quick, making the needle on the tac tick. Other times it'll take 4-6 seconds to fluctuate. RPM also hangs when coming down from anything at 4k rpm or above. Often taking 2-3 seconds to return from 4k to Idle.
 

This to me says that the idle mixture screws aren't set quite right. I'd try adjusting up or down until it smoothes out.

Quote from: Warp84 on February 26, 2026, 08:52:49 PMTrying to dial in the Carbs on my 84 1100 and been having issues getting it smoothed out.
We tried doing a leak test at the intake manifold and the vacuum nipples but couldn't locate one. Despite that, I still think part of the problem is a vacuum leak on the intake manifold. But I would like help sorting out all the issues so I can finally get this old girl back on the road for this riding season.

Warp 84,
To find a vacuum leak, use aerosol spray-can ether (starting fluid). With the engine running, spray a little on each part of the intake system in turn. If spraying any one place causes a change in RPM (up or down), you just sprayed the vacuum leak place. Repair as needed. HTH.   

Quote from: Warp84 on February 26, 2026, 08:52:49 PMTrying to dial in the Carbs on my 84 1100 and been having issues getting it smoothed out.

Pilot Fuel jets are 42.5's, replaced all the o-rings and gaskets in the carbs. The carbs were cleaned in an ultrasonic cleaner.

When running, the bike responses quickly to throttle, but is showing other issues. When on the centerstand and holding the throttle in place, the RPM's will fluctuate up and down by 500-1000 RPM. Sometimes the fluctuation is quick, making the needle on the tac tick. Other times it'll take 4-6 seconds to fluctuate. RPM also hangs when coming down from anything at 4k rpm or above. Often taking 2-3 seconds to return from 4k to Idle.

We tried doing a leak test at the intake manifold and the vacuum nipples but couldn't locate one. Despite that, I still think part of the problem is a vacuum leak on the intake manifold. But I would like help sorting out all the issues so I can finally get this old girl back on the road for this riding season.

Slight Correction. When I say hanging RPM's, I mean slowly returning to idle. Not getting stuck at a particular RPM point.

The Bike was getting actually hanged up when it was using 37.5 pilot jets, not crossing past 2.5k RPM, shooting up to 4k and staying there. But haven't had that specific issue after I put in the 42.5 Pilot Jets.

Trying to dial in the Carbs on my 84 1100 and been having issues getting it smoothed out.

Pilot Fuel jets are 42.5's, replaced all the o-rings and gaskets in the carbs. The carbs were cleaned in an ultrasonic cleaner.

When running, the bike responses quickly to throttle, but is showing other issues. When on the centerstand and holding the throttle in place, the RPM's will fluctuate up and down by 500-1000 RPM. Sometimes the fluctuation is quick, making the needle on the tac tick. Other times it'll take 4-6 seconds to fluctuate. RPM also hangs when coming down from anything at 4k rpm or above. Often taking 2-3 seconds to return from 4k to Idle.

We tried doing a leak test at the intake manifold and the vacuum nipples but couldn't locate one. Despite that, I still think part of the problem is a vacuum leak on the intake manifold. But I would like help sorting out all the issues so I can finally get this old girl back on the road for this riding season.

Quote from: Bones on February 26, 2026, 02:32:47 PMDo you have the standard clutch master cylinder fitted, I fitted an FJR1300 clutch master to mine that had three prongs on the clutch switch instead of the FJ's two and no matter which way the wires were fitted on the prongs everything seemed to work backwards to normal, like bike would start in gear with clutch out etc.

I had to pull the switch apart and delete one prong and bend and move another one around so the plug would fit on and now everything works like it should, had me stumped for a while though.

My clutch switch has only two prongs...

Do you have the standard clutch master cylinder fitted, I fitted an FJR1300 clutch master to mine that had three prongs on the clutch switch instead of the FJ's two and no matter which way the wires were fitted on the prongs everything seemed to work backwards to normal, like bike would start in gear with clutch out etc.

I had to pull the switch apart and delete one prong and bend and move another one around so the plug would fit on and now everything works like it should, had me stumped for a while though.