1984 XL200R
 

This is regarding a 4-stroke offroad motorcycle, by the way.

I have an '84 XL200R. It starts up perfect, with full choke, and idles great. At idle, if you deprive it of its choke, it dies. It even dies down in revs at 3/4 choke.

With full choke, sitting in neutral, it goes up and down the powerband no problem. However, when I take it along the road (with full choke), it struggles to get up to speed, and doesn't get far beyond ~3,000 RPM. Once after riding for about 5 minutes, I decided this would be a good time to give it no choke, and I did, and the engine responded by nearly dying.

Also when in neutral and coming down from high revs, it backfires out the exhaust. *

*Actually not so much a backfire, but a cough. It's not like a BANG but it's there.

What gives?

Sounds like its not getting any fuel. Its limiting the RPM's, its getting just enough to keep it idling with no load on it, and the backfire is a lean backfire.

Okay so what you're saying is carburetor scuzz...

And too lean of..? Air-Gas? Vice versa? Oil-Gas? Confusion reigns.

Not enough fuel for the amount of air coming in. Could be carburetor problems, or something as stupid as a collapsed fuel line, etc.

Snakeyes, you bought the bike?

Today or tomorrow wakelagger.

Today being Tuesday the 8th