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Running lean?

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Member
Joined
Mar 18, 2021
Total Posts
37
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0
Location
Pittsburgh, PA, USA
Plugs are showing lean and I’m trying to figure out the cause.
I’m running a GM coil with new leads (resistors removed) and iridium plugs. Would the iridium plugs make a difference in showing a lean condition?
75, 118.
Valves adjusted.
Checked for air leaks, none.
Carbs should still be sync’d.
OEM airbox, fairly new air filter.
Mixture screws adjusted.

The engine seems to get pretty hot.
Up another size on the primary?

Thank you.
 
The plugs are showing slightly lean, I'm not familiar with the Iridium plugs so that may make a difference in what I'm seeing. The white ceramic is looking like it's taking on a very light tan, light tan is where you want to be.
Which carbs are you running?
Have you check the air cut valve diaphragms? If they're leaking they introduce air into the mixture directly after the throttle plate which is essentially a vacuum leak but undetectable.
Your jetting is as rich as I've run on VB22's
Need to get the sync done so you can properly set the mixtures, has to be done with sync'd carbs.
 
VB22s.
Replaced air cut diaphragms with aftermarket not too long ago.
I’ll check the sync again. Using a homemade manometer though.
 
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