Right Cylinder Running Richer Than Left

j343my

XS650 Enthusiast
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Hey guys, new XS650 owner and first time poster.

I'm working on tuning at the moment and I'm having a hard time figuring out why the right cylinder is running richer than the left. This is also my first non dirt bike motorcycle and i'm not super well versed in older bikes.

Some details:

Cam chain & valves adjusted. Boyer Ignition, timing set properly. Hugh's PMA with fully charged battery. VM34s with uni filters. Pandemonium ya mama exhaust. Compression 150psi in both cylinders.

Some things I have tried:

-Checked for vacuum leaks with starter fluid spray
-Swapped plug wires/sides of coil
-does not appear to have exhaust leaks

Today I swapped the carbs from one side to the other. Warmed up the bike, put in fresh plugs and took it for a ride. The end result is pretty much exactly what I have always been seeing. Evidence the right cylinder is running richer than the left when looking at the plugs after as seen in the photo.

The only thing I have not tried is a proper carb sync. Only a bench sync to this point. I have ordered a carb sync tool, and will try that when it arrives.

All this being said, the bike starts easy, idles well, and runs really well out on the road. Great throttle response, pulls hard and no stumbling or popping. I'm just perplexed as to why i'm seeing this difference no matter what.

Thoughts?


20220715_185253.jpg
 
Being you changed carb sides even, I'd think that there is oil getting in that chamber or a weak valve spring.
 
When you swapped carbs, did you bring the uni filters stay with the cooresponding carb (moved carbs and filters?)
Not syncing carbs can make one cylinder run harder and the other easier.
 
Have you checked the float level? A sinking float can cause rich running and even worse if it sinks entirely.
The best way thatI have found to check the float level is with a sight tube. I use a 1/4" piece of vinyl tubing that I have beveled using a pencil sharpener, This will fit into the output for the drain plug. Just screw in the tubing. The level should be 3-5mm below the bowl gasket line. This can be checked in situ, but the adjustments and following measurements should be made on the bench.
 
Petrol only, no oil.

Recheck floats like some said.
Bike on side stand?
This may cause overly low fuel level and float valve dribbles fuel in un-controlled.
Opposite on left side.

Looks like no Plug Chops have been done, let alone run it for an hour at P/T just for color.




cliff
 
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