Main Motorcycle: 1996 900 Trophy BRG
Join Date: Mar 2008
Location: Apple Valley, California
Other Motorcycle: 1998 Sprint Sport
Extra Motorcycle: 1996 1200 Trident
Hi Hoop, Here's a bone but you aren't going to like it. The problem is either coils or spark plug wires, or both.
New coils are expensive, used coils are a crap shoot. Same thing with spark plug wires, expensive new, crap shoot if used. Have you considered changing over to stick coils. You won't need spark plug wires and stick coils work great on my 900's. As far as carbs go, yes your bike came with Mikuni's. Some previous owner switched it over to Keihin's searching for better fuel mileage. I tried the swap and went back to the Mikuni's. I found the only carb jets that get clogged up are the idle (low speed) jets. The main jet is pretty big with the slide needle passing thru it so the main jet can't get clogged. A vacuum leak shows up mostly at slow throttle openings.
Here's another thought. The rubber carb manifolds might be wrong because of the conversion. The Keihin carbs use their own rubber manifold. Mikuni uses their own. They look very similar as if they would be interchangeable, they are not. Can you take the carbs off? Keep the cable attached to the carbs, disconnect the cable at the throttle twist grip. Then take the carbs and a manifold to Engle Motors let them check it out. By the way, I used to live in Shawnee, Ks.