Big Red not running right

[RadRacer203]

Just got a new coil and carb hat in for my new-to me Big Red 200es. I swapped an original Keihin carb back on to replace the crappy chinese one that was on it and same with the coil.

The engine seems healthy as far as I can tell but I can't seem to get it to idle down or rev. With the Chinese knockoff carb it ran a bit better but not much. It still sputtered and coughed and wouldn't idle, as those knockoffs tend to do.

The carb on it now is stock from a different 200 (200m, 200e or something, came from a buddy's parts bin) and I have a good used cap and slide from ebay. I can start it up and it starts basically as soon as I bump the starter, but it stays at what sounds like 2000 rpm and I can't get it to come down from there adjusting the idle speed screw. What might be causing this? I haven't experienced this on anything else before.

When I push the throttle it also coughs and wants to die, so I assume it's running lean? Possibly an air leak from somewhere? I can't keep troubleshooting today cause of rain but if anyone has any input I'd really appreciate any suggestions on what to look for.

[Thorpe]

Too much tension on the throttle cable?

[kb0nly]

Sounds like its running lean, sucking air around the intake most likely. Did you replace the o-ring between the carb and the intake? How about the o-ring between the intake and the head? With it running try spraying some carb cleaner around the intake, sometimes those crack in the rubber flex part in the middle, spraying some carb cleaner or flammable brake cleaner around it you will hear the difference in the engine and know you have a leak.

Beyond that make sure the needle in the slide is in the right clip setting, and check the throttle cable is letting the slide go down all the way by looking in from the airbox side. Generally not wanting to idle down though is running lean.