That info makes sense and this afternoon I will work at adjusting the carb unless of course Rita ,my dear wife ,has found where I hid the honeydo list.

 

Bought a Clymer service/repair manuel ,excellant reference,from info gained on this site figured to tune carb....pilot air adjusting screw.This Mikuni carbs only markings are 24C9 & H6x2.Bench inspection of carb shows no adjustment or plugged access to adjustment other than idle speed.Its going back together and I'm living with backfire until further info gained.
Been a learning experience and as the Clymer suggests am installing an inline fuel filter so not a complete waste of time.

 

yes, it will cause damage over time depending on the frequency and severity

 

its all about the jetting and tuning; if done by someone who knows what the heck they are doing it takes all of about 20-30 minutes and problem solved
it seems that a lot of the people working in the back are no longer trained to understand how a carburetor works and how to solve problems with them; all they do is read in the manual what the factory says should be done with the EPA looking over their shoulder and dictating "this much and no more".....makes for crappy running bikes that backfire

 

Please tell us "where is anti backfire valve located? On the right hand side of carburetor? Assumed if we sit on the motorcycle the right side is the right hand with the gas throttle. Can you post the picture?

 

Lots of different names finding out,proper name transient fuel valve(anti back fire)on right side of carb as seated under triangular cover with 3 srcews.Done that, minimal if any improvement.Then removed welsh plug and adjusted air/fuel mixture,considerable improvement....thought it was fixed,still gives a little backfire winding down when ignition turned off.Going to try shim up main jet but have not yet.

 

This is the correct fix. And in California they have a brass cap over the FUEL screw (Some techs here have called it an AIR Screw). Remove the cap and adjust to the best idle.

Backfire will be gone.

 

And if you ride on the freeway the exhaust gasket between the muffler and head pipe will start to leak. That can also cause the Backfire too.

 

I have an 07 Boulevard S40 with 2500 miles on it. It was given to my by a good friend who basicly had it in storage most of it's life. This is the second Savage that Ive owned, both of them prone to backfire. The main cause for these happening is that the bike is running too lean do to government restrictions put on the factories. I took my "07" S40 to a trusted motorcycle mechanic (not a dealer service mechanic) and had him trick my exhaust and put a performance jet kit in the carb and am very pleased with the results! Runs and sounds great and is minus the backfire. I might add that there is a noticeable increase in power as well!

 

Yep, first thing I would do is have the bike rejetted, as the bike is probably set up too lean from the factory. Wise words!