engine running rough

Hi, all!
I just joined the Swing community in purchasing a used 2009 with 1600 miles on it.
It apparently had been sitting around a while and I needed to replace the battery.

Started up just fine, ran around town a few miles and it seemed to be running a bit rough (noisy, vibration). Sounds fine when I start up, but when I accelerate, it roars a bit and I feel some rough vibration through the seat.
I popped out the old plugs and put in a couple new ones, checked the oil, which was fine, and put in a fresh tank of gas, but didn't seem to help much.
Accelerates just fine.
Can any one help me with suggestions what might be the problem?

(Note: I'm a newbie to bikes, just started riding a year ago and moved up to this Swing.)

Thanks! I'll look it up.
This forum is terrific!

Mine does.
It's as if the transmission hasn't caught up with the speed and acceleration and is desperately trying to do so.
I do what bigbird suggests and back off the throttle a bit then gently increase the revs again - gives it a moment to recover!

No vibrations.

When opening throttle, there is a rude noise out of the exhaust.

Have you looked at the air cleaner? A dirty air cleaner could impede air flow thereby causing a rough engine. As for the Costa variator reducing mleage, I doubt that is true. I've had the Costa on my scoot for many months and still get the same 48 to 50 mpg I got prior to installation. I think one reason people may get less mpg after installing the Costa is because they tend to twist the throttle a little harder to enjoy the increased performance :lol!:

Good idea!
I found the pictorial on doing this. It looks a bit involved but I'll give a try once I get a filter!
Thanks!

drbyte, you might also want to check the variator and the rollers. If your rollers are sticking, it might cause vibration or rumbling upon acceleration.

Could you take a glance at your speedometer and tachometer while riding and tell us what kind of rpms vs. speed you have? Be sure it is a steady speed and not increasing/decreasing speed.

At 1600 miles on a 2009, it seems unlikely to be a rough running engine. Since you said that it appeared to be sitting for a while, have you tried any fuels system cleaner (like SeaFoam?). If the old fuel got stale and clogged the injectors, fresh fuel will take a long time to clean them. With the ethanol that is in so much of the fuel these days, fuel goes bad unless winterized.

I looked at j costa variable info and I think it is unlikely that there might be a lot of roller wear after 1600 miles (and it looks like a lot of work to take a look inside!)
Where can I get seafoam fuel line cleaner? I've never used this before. It it just added to the fuel tank?
Thanks for your help!

Seafoam is a fuel additive. It's available at Wally world here and probably at most auto part stores. Just add it and run it.

Looked it up on the Internet, thanks.
Has anyone used this by direct injection into the engine cylinders (as mentioned on their website) to more quickly clean out deposits?
If so, what engine vacuum hose does this go into?