83 virago runs on one cylinder

[81/3virago]

ive been fighting with my virago since i bought it a month ago... started completely bone stock if you got on it she would drop the front cylinder below 3000 rpm's but pick it up once it reached 3k. so i pulled the carbs off drained the tank and cleaned everything. same. i added jardine slip on straight pipes and a jet kit (dynojet stage 1), same. i bought a parts bike pulled the carbs cleaned and added my jet kits to them and put them on same problem. decided i might be floating front exhaust valve at high rpm's and it was sticking open. put in complete parts bike motor and tranny. now im dropping the rear cylinder. changed out spark plugs air filter looks good. any suggestions other than taking it to the shop? i try to do everything myself.... i managed my first motor swap in 2 1/2 hrs

[2005GZ250]

Check the wiring harness and connections. Had a car in the shop Friday that ran like crap in drive but ran great in rev! The problem was while in drive the wiring harness would ground out because the motor mounts were going bad making the engine pull on the harness. I don't think you have a mount problem but when you changed the engine you had to move wires and now there is a problem with the other cylinder so my guess is there is a bad connection at a plug or a wire is grounding to the frame.

[Ejh]

Check the the Diaphragm on the top of the carbs,the slider, my brother had this problem and it was the diaphragm on one the carbs had a crack in it.

[Aussie Steve]

I would also check electrical to that cylinder...start at the cap and work back to the coil. If in doubt swap offending parts with those of the running cylinder to see if the fault moves. If you have two coils swap them over complete with cables and caps.If its a single double ended coil then it becomes tricky unless the motor runs on the lost spark system in which case it make no difference which cylinder is connected to which end.

Good luck