I'm looking at a 90 bagger that is for sale locally. I haven't seen it in person or rode it yet. The owner states it has a upgraded cam. It has a Thunderheader on it also.
he said it has a flat spot when accelerating between 2800 and 3000 rpms. After 3000 RPMs he says it pulls strong. He bought the bike through the estate of the original owner so his knowledge of it is limited.
Any ideas what could be causing the flat spot? i wonder if it could be the jetting of the carb? Thanks, Todd

 

Jetting of the carb, ignition timing, or he picked a cam not happy with the size and compression of the motor he put it in.

 

Without knowing the carburetor and how it's setup, impossible to say what it would take to eliminate the narrow rpm flat spot.

 

It can be made right, so if you get it...go to the dealer and get it dynoed....if the mechanics are worth their salt they can figure out a path for you....many techs are drilled on fuel injection and modding the ecu, but a dealer that works on the old bikes will know what is going on and how to remedy it. My dealer will wrench whatever you bring in...and to put my EVO bike on the dyno just to see where I am at costs about an hour of shop time...I want to do it see if at least I am still making what the MOCO designed her to do.