Popping and backfires when decellerating - 2005 Yamaha V Star 1100 Silverado

Well - the front pipe has to be removed to change the oil filter on this bike, so it's very likely that when reinstalled the mechanic did not get it back in place correctly. Couple that with the likelyhood that he re-used the old exhaust gasket and this is your most likely cause for the backfire - a simple exhaust leak. Other typical causes for exhaust backfires are insufficient valve clearance, burnt valves or incorrectly adjusted carbs. In my experience the most common cause for exhaust backfire is a leak in the exhaust circuit which can draw in fresh air during decelleration.

if is doing it thru the carb then the fuel mixture is too lean, if is in the exhaust (also called after-fire) the fuel mixture too rich.

Yes and no is the answer. If its the stock KTM pipe it should not backfire, if it has an aftermarket pipe (race pipe) there is a good chance it will. You should make sure all the exhaust joints are sealed properly as this will contribute to it. If its a race pipe, make sure the bike has had the carb rejetted to suit. Genrally, with a race pipe you will get some popping when decellerating even if it has been set up correctly.

check to make sure you didn't get bad gas some where is it a cali model be couse your carbs can over flow and you will never know it just all goes into the charcoal canister in the front bottom of the radiator is allow raw gas to enter in the air side of the carb un metered

a four stroke will pop and backfire under decelleration when it is lean, or not enough fuel. (Jetting too small in the carburator) But, look at the spark plug for color, white is too lean, black is too rich, and chocolate is just right. Make sure the air filter is good and clean. And lastly... have the valves been adjusted?

Also, it will pop on decelleration if it is too lean

i would recommend you to get the cylinder pressure checked.

clean the carburator and the air cleaner also clean your spark plug or instead replaced it with new one. denso irridium would be the best for it.

that seems to be what they do, i too have a 650a and have jardines on with baffles, it still pops and cackles when you roll off the gas. are you running no baffels? when i took mine out i noticed a drop in power as i had removed the requierd back pressure for optimum performance. you can get small baffles to slip into straight pipes from jc whitney for about $5 each.
anyway back to the backfire. my local bike shop shrugged their sholders when i asked them about mine saying it's what they do. you will get used to it and you will find a way to kinda not make it do it so much. i actually have grown to like it now, except when there are cops about.

happy safe riding

Does this happen when closing the throttle? Under hard accelleration? All the time? Could be 'decelleration popping' as they jetted bikes pretty lean back then. It is common. Honda XL's and XR's came with a wire mesh screen in the airfilter to keep sparks from this lighting the airfilter on fire. If it only happens with closed or partly closed throttle, it is no big deal.