I wouldn't have thought putting pod filters on was a thing an old man would typically do. They can work if they're set up right, but don't old guys usually stick to stock?
Also, the fact he gave you the wrong manual is a bit confusing, unless he had a collection and was just getting forgetful.
Do you think it's a possibility the bike may have belonged to his son or grandson, and he was getting shot of it because it had been sitting there for ages?
In any case, in that situation what I would do is assume the pod filters were set up correctly, i.e. put the needle clips back to where you found them. Just service the carbs, get them completely clear, and see if the bike runs properly. If it does, leave it at that. That would be my approach - if he says it worked then see if that's true, because it might be true. If you want to return in to stock that's always an option but parts for rare bikes like that one are getting expensive and it may take you some time. Blocked passages in the carbs and blocked jets, and general maintenance, might be the culprit for the bike not getting enough fuel-air mixture.
I thought so too, but it's a two owner bike and I think he put the sidecar on for stability in order to keep running. I have the original bill of sale from the first owner.
I suspect someone took the box out and didn't realize how much of a chore it is to reinstall it, so went for pods.
I think the wrong manual was confusion because of the bike's name being all over the place from Kawasaki. The bike say "750 ltd" so he went and bought the clymers for that model, and just figured it was close enough, not realizing there was a 750 ltd 4 and twin.
I actually already sourced an airbox, cleaner, and boots and installed everything. Thats part of whats throwing me, because that amount of change in airflow should have some impact, you know? So if it's not airflow then it has to be "above" the lamilar flow in the order of operation, right? Leaving spark and fuel (or even compression, but it seems solid).
So I suppose pull the carbs and clean them. Could I get away with pulling the jets and not pull the carbs, do you think?