Jet kit,vance n hines,k@n, ran well for 500 mi now runs rough at low rpm and backfires some when downshifting.i put new plugs and fuel filter on it.bike has 5000 mi on it

Sounds like this may be a carb issue,,,, time to have a professional clean, set, and synchronize them!!

I have a 2007 Honda Shadow Sabre VT1100 and I also put after market pipes on it from Vance and Hines. I also have to keep it choked when first starting and sometimes even hold the throttle a bit while it warms up. The bike has two carburetors and the best solution I have found by lots of asking around of mechanics and bike folk is to get it rejetted through Dyno Jet. It is meant for bikes with after market exhausts and much less back pressure from the lack of those stiffling baffles in the stock pipes. I have also noticed the power loss in the middle torque range and backfiring because of the bike running in a lean condition. The Dyno Jet website is a good place to find the correct set and corresponding part number, but then I suggest finding a cheap place online so you avoid retail price :) Hope this helps. Oh, and don't forget to buy two kits...we have two carburators in our bikes.

try to find connector and plug it up

If you have carburetors you need to install a jet kit. If you have a fuel injected bike you need to add a Power Commander and program it for the changes you have made to the intake side of the engine. Make sure you installed all new exhaust gaskets or you will have lots of popping and back firing.

When you installed the Vance and Hines pipes did you use new gaskets? Popping and backfiring is often caused by leaking copper o-rings in the head to head pipe connection , or head pipe to muffler gasket. Sealing the system will prevent oxygen igniting the unburned fuel in the exhaust pipe. Hopefully , this is all you need to stop the popping.

It sounds like you fuel map is wrong. Motorcycle are extremely sensitive to any changes you make in the intake or exhaust system. Sounds like you need to take your bike and have it put on a dyno to figure out the new map for your fuel. I'm not familiar with the the Vance & Hines fuel pack. Sorry I couldn't be of more help, Good Luck, Steve

Try and get the carbs balanced .You may have one in need of adjusting .

general rule of thumb is to go up about 10 jet sizes,unfortunately it is a bit of trial and error,and you may have to swap out diferrent sizes to get the bike running right,(jets are quite cheap though)but first step about 10 sizes from standard,your local dealer should be able to tell you what jets are in it and supply replacements,if you change to a hgh flow aftermarket air filter you may have to change jet sizes again as changing the filter may effect the mixture ratio in the carbs,,hope this helps

sounds like its starving a bit , try adjusting the fuel air mix screw,  Take air filter out and give it a good clean first before any adjustments ok?

Let me know via [email protected] if you get a solution, Mine is doing similar but mine is holding back at half throttle to, Wont rev high at all just chokes under load