2026-05-11 Chocolatie Dead #1 Cylinder
I had noticed that the left-hand side muffler had uneven pulses as compared to the right hand side. Occasional back firing, popping.Thought it was the OEM carburetor that Herb contaminated with particulate rust after using vinegar in the tank and not installing a fuel filter.
So I installed a carburetor rack I had rebuilt and the bike runs the same. Unlikely it's a carburetor issue.
Compression, Fuel, Ignition. Simple. Right?
Started with a compression check.
Here are the results.This is with the throttle closed. Cylinders 1, 2 and 3 used motorcycle battery alone and cranking got to be a little slow.
Put a 10 amp charger on the battery to measure cylinders four, five, six. Units are PSIG.
135
120
120
130
120
120
That's 11.1% delta when 10% is great. Close enough given battery condition and closed butterflies.
Measured the ballast resistors. Units are Ohms. 1.7 Ohms all three.
- Plug one is sparking when grounded externally
- Checked plug 1 cap resistance ~4.5k Ohms
- Cut plug one wire back 5mm and check from bare wire to ground - strong spark
- Reconnected cap - spark about the same as other plugs (daylight reading)
- Run engine - still missing on cyl 1
- Used ColorTune - no fire in 1. Cylinder 6 looks great - nice and blue
- Sprayed WD-40 into the inlet port that connects to the manometer and she instantly had combustion - so cylinder one has no fuel to burn!
Installed another rack that I rebuilt - and, evidently, I'm not yet a good carb builder cause this rack ran like crap - choke had to be half on to run, popping and ugly.
Sync, even though done on bench,way off.
Good thing though, cylinder 1 head pipe had *some* warmth
Installed yet another rack I had rebuilt.
This time, MAGIC happens. Cylinder 1 instantly starts making heat, the the manometer shows fairly close readings from a bench sync, and both exhuast pipes now have good even pulses. So it's a carb related issue.
I do not understand two carburetor racks are not providing fuel to cylinder number one, and cylinder number two is working perfectly.
If it was one carburetor per cylinder, I would think fuel inlet issues, incorrect height in the bowl with a common bowl and number two looking great, but could possibly cause number one to have no mixture across all 3 circuits? 
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