Vulcan500.com

My GF's 500, I think '03 model, has poor off idle throttle response. It bogs and will even stall. Runs better when warm but still not as crisp as I think it should be. Runs like a top at upper throttle settings.
Starts easily on choke, takes long time to really warm up though. Bike is all stock, no mods to air filter or exhaust.
I've replaced fuel, used Sea Foam, changed spark plugs and replaced battery.
I would think that it needs a good carb cleaning. Any opinions?
If so how big a deal is it and which jets/passages are the most suseptible?

First off welcome to the forum!

If you are running OK after getting past off idle then you most likely have some restriction in the pilot screw (idle mixture) passages. Definitely sounds like it's lean. Does the bike have super low miles and sat a lot? If so then a few healthy doses of SeaFoam MAY help clean it out. You'll most likely need to pull the carbs and give them a good cleaning though.

Other things to check for: Fuel and air filters, clean or replace. Check for vacuum leaks at all rubber hoses and cracking at the carb to cylinder head rubber boots. Have the valves ever been adjusted? Tight valves can have a huge affect on performance.

Consider building a low buck carb synch tool. It'll make a massive improvement in the way the bike runs if the carbs are out of synch.

Joe

If you're not certain about how to build a manometer (carb synch tool) here is a good link on how to build a nice one on the cheap. http://www.obairlann.net/reaper/motorcycle/manometer.html

Joe

When I've let my bike site for so long the carbs get gummed up and it will run like as you described. I usually use a bottle of carb cleaner in the tank and then after about the 5th tank of gas it's running smooth across the throttle range again.

Using STA-BIL in the fuel if you' know you'll be letting it sit a while significantly reduces this problem.

Thanks guys, I've got a sync tool left over from my old Honda 4 days.
I'll try a heavy dose of carb cleaner in the gas and if all else fails I'll pull the carbs and give them the once over.

"And what to my wondering eyes should appear, but rocker arms and 8 tiny screw tappets in here" in a DOHC set-up no less.
I was taking your posts to heart and figured I would check all avenues so ordered a Haynes manual and leafed through after it arrived. I was expecting shim under bucket lifters and was shocked to discover something that is so crudely simple as screw tappets

That's half the reason I bought this bike, easy valve adjustments.