Won't run with air filter

[Mont]

My '78 XS1100 runs great without the air filter, but as soon as I put it on, it won't run. I turned the adjustment screws in almost a full turn thinking it was running too rich, but that didn't help. The filter isn't dirty, but it evidently is too much air restriction for the settings. Any ideas?
Thanks.

[CatatonicBug]

Just a few questions to get them out of the way - Are you using the stock airbox? If you are, is the snorkel clear (critters like to build nests in there)? What kind of filter are you using? Is the filter clean/properly oiled?

Are you saying that the engine won't run at all with the filter installed, or it just runs poorly?

[prometheus578]

I just reread your other posts. Sounds like you're still not running on all cylinders.
Check your spark plugs. If you have a wet or sooty plug, you'll need to replace it.... then have to find out why it's fouling.

Since it only runs with the airbox off... with the airbox off start the bike and let it idle for a few minutes. Spray some water on the header pipes and see which pipe doesn't sizzle. There's your dead cylinder.

Dead cylinder... idle drops too low... airbox restriction adds extra "drag" to system... engine dies.

If all plugs (and I mean clean plugs) are sparking, then it's carbs.

[natemoen]

What are your compression numbers?