Sputters under medium throttle, any ideas?

I bought an 82 Honda Magna 750 v45 last weekend. Bike is in overall great shape. I've been riding it for a few days now and it's got a sputter/miss in it until it gets to about 5,000 rpm unless you're accelerating softly. It will cruise nice and smooth and will go like hell if you get the engine up above 5 grand and open the throttle, but under medium and hard throttle below 5 grand or so it will miss a little. I called a Honda dealer and they said I need the carbs pulled off and re-jetted and cleaned. Does this sound like a valid solution? Should I try some carb cleaner in the gas first? Should I run some alcohol blend it it (10% ethanol ; water issue?) Should I try new plugs? How about any other suggestions on this issue? All replies are appreciated. Thanks,

More bike info: 14,000 miles, idles smooth, starts fairly easily: just have to give it a little throttle and fires right up. Engine is very quiet (except exhaust). Does NOT backfire or anything. I'm stumped and don't want to spend $300 if I don't need to.

They are right, it's probably got a clogged mid-jet circuit, running to lean under certain circumstances. If it were mine, I'd close the petcock, let it run until the carbs are dry and it dies, then take the fuel line off at the petcock and spray carb cleaner straight down the fuel line until it fills the carbs and starts to back up (watch your eyes and paint!). t

Then reconnect the fuel line, start it up, and run it (it will run on the carb cleaner) in that RPM range for a few seconds, then shut it down. Let it sit about 30 seconds, then turn the fuel back on and ride it in the range that gives you problems right away. It might sneeze and pop a little as it burns the cleaner out, but you want to get it flowing through that circuit.

If that doesn't change anything, you'll have to dismantle the carbs an physically remove the restriction from the jet.

have you checked for fouled plugs as well?

Since this is a used bike, you may want to pull (or have someone you trust pull) the carbs to see if it has a jet kit installed. Does it have aftermarket or modified pipes? If you ride in that range and slowly apply the choke, does the condition improve? It could just be running lean in the middle and needs to be adjusted. Check to make sure no one has removed the snorkel fromt he top of the airbox as well. Good luck.

i had a problem like this with one of my bikes and i had the carbs cleaned and it ran like a dream afterwards....either way it'll be a cheap fix:)