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First off, I have an '07 Vulcan 500 with about 1300 miles on it. I haven't really done any maintenance except for an oil change and new plugs. All this motorcycle stuff is unfamiliar to me. I am fairly experience in automotive maintenance but the motorcycle world is new to me. So, the issue I am having is that my bike idles pretty rough and when I go to take off it hesitates really bad and then all of a sudden just takes off. Throughout the entire RPM range it misses intermittently. It also pops really bad on deceleration. I am pretty sure it's a maintenance issue, but I am not sure what. I haven't checked the valve adjustment yet and I haven't balanced the carbs yet. Someone suggested that maybe the jetting is wrong since I originally had this bike in AZ. Now I am in FL with a totally different climate. I pulled the plugs and cleaned them, but it still runs like crap. Any ideas?? Thanks in advance.

Good bike. I like those.

What was the elevation where you were living in AZ?

Did it ever run right once you left AZ?

Has the bike been left sitting for any long period of time, over a month, without being run?

Did you gap the new plugs according to the manual? (Do you have a manual? They don't cost much and it will help a lot, I like Clymers manuals better than the shop manual.)

A quick easy test to see if both cylinders are running, or if you are only running on one cylinder: start the bike and immediately start touching both exhaust pipes where they exit the engine. They should both get very hot, very fast. Are both of them getting hot at the same rate? Is one side hot and the other side only warm or cold?

If both cylinders are firing, then it looks like a carburetor issue. Especially if an '07 with only 1300 miles has been left sitting. The gas has likely gone bad inside the carbs and clogged them up. If this is the case, you are definately going to need that Clymers in order to take the carbs off, open them up, and clean them. It is not a hard job, but it must be done right and carefully or expensive things will break! But you can do it at home.

What more can you tell us?

Elevation where I was in AZ was about 4500 feet. It was running right after I brought it to FL for awhile. I didn't ride to FL (obviously). It does sit for a couple of weeks at a time sometimes. I don't ride it everyday because the weather is too hot and humid. Not sure what the gap is, but when I originally put them in they were gapped correctly. I haven't changed the gap since then, but I am also not sure if it has changed. Not sure how it could. I will check the temp of the pipes to see if it's both cylinders missing or just one. It's not a consistent miss though, so we'll see.

Just did a seach for a clymers manual for this particular bike, but have found none listed

Update:

I checked the temps with my non-contact thermometer and found a difference of about 10-20 degrees. The left side (number one I think) being warmer. So, this leads me to believe that the right side is firing *sometimes*. So what else would cause this besides wrong gap on the plug? I still need to check that, but I would like a list of things I could check

10-20* temp difference between cylinders is not that much, I don't think it's down to just one jug.

It does sound like a lean condition from over here..... I'd do the balance/tune work to the carbs first and see how that affects it.

Update:

I pulled the plugs out to check the gap and the number 2 plug (right side) was definitely more fouled than the other. I double checked the gap which was gapped at .025, right on spec. So, I switched the plugs to see what would happened and after a short ride determined that I fixed nothing. I checked the temp difference again (after it was completely warmed up) and saw a difference of about 70 degrees. ~130 degrees on the right side and ~200 degrees on the left. Seems to me like it's richer on the number 2 cylinder. If I keep the throttle steady I can hear popping sounds most likely from unburnt fuel igniting in the exhaust. Under deceleration it's much more pronounced.

More experienced folks will speak up, but I'm going with fuel issue. I think you are going to have to pull the carbs and clean them. If it ran right when you moved to FL, then the jetting wasn't off.

This might be worth a try before you do that: get yourself a can of Sea Foam and put half of it in the tank and ride, ride, ride that tank out. Fill it up and put the rest of the can of Sea Foam in there and ride it out. Sometimes it works to clean out only slightly dirty carbs without pulling them off. Won't hurt, at any rate.

What else causes intemittent misfiring...let's see...lots of little silly-seeming things, like, are the plug wires and plug boots intact, not rusty, not damaged or kinked or torn?

You live in FL--for sure you better get good at checking electrical connections! The salt air will do a number on them. There are electrical wires coming off your ignition coil, clean the connections there no matter how good it looks. Remove the coil and clean wherever it grounds, whether it grounds right to the frame or through a wire bolted to the frame.

Follow the wires from the coil to where they come out of the engine, check for breaks, crimps, tears in them. A bungled-up wire would cause this.

Last thing I can think of is checking the connection at your CDI box, little black plastic box mounted usually on the rear of the bike. I got water in mine once and caught heck trying to find why the ignition was misfiring.

But I think the bike sat for too long using the same tank of fuel and your fuel is going bad.

Cool, thanks for the tips. I'll keep trying these things till I figure it out. If I ever figure it out I will post my results here.

So, here is the update: It started getting worse. When I revved it, the RPMs SLOWLY dropped. I checked the throttle linkage and it returns just fine. So, I think something is sticking inside the carburetor. I drove it with the seafoam for awhile hoping that it would clear it up, but it didn't. I finally parked it, deeming it unsafe to drive because the throttle is sticking. After ahwile, it wouldn't start anymore. Plugs were way too fouled. I am think party because I put in too much seafoam. So, I am pretty sure it is a carb issue.

I have it all taken apart now. I went ahead and adjusted the valves, which needed adjusting, but weren't too bad. That's done, now I have the carbs all taken apart. I just have to clean them up, check settings, and reassemble. I am really crossing my fingers.

Isn't it often related to ain intake leak if the revs drop too slowly? Or was it a torn diaphragm?