hi jgarrison,been reading your posts,i have a similar problem,wondered if you ever sorted it and what it was. thanks
Did either of you run a compression test ,I was just wondering,the order for trouble shooting is always..Compression ,Ignition and then fuel.If you are down on compression, good spark and fuel mixture,won't help any thing.
And use a compression tester ,just because it will blow your finger off the spark plug hole doesn't mean it is up to snuff/I can't remember offhand how many psi it should be but it is in the manual.Low compression means low vacuum as well and your carbs are CV carbs that require a healthy vacuum signal to pull the slide up inside the barrel of the carb.
My next step would be to check for vacuum leaks,just because you are getting fuel thru the petcock does not necessarily mean it is good.It is a prime place to look for a vacuum leak ,especially check the hose going to the petcock,It may have a small hole in it and it could be soft and collapsing in on itself and not allowing enough fuel flow for higher rpm running.
Last but not least is check your float settings they may be set to the point where it is simply running out of fuel at higher rpm's.
I skipped over the ignition part because from what I gather from both of you guys is the engine is running well at lower rpms.
Some food for thought and I hope it helps one or both of you with your problems
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