Well if backfiring was what you needed to fix why didn't you say so...

Shutdown bang... 1/8 turn CCW of the idle mixture screw
Shutdown KERPOW... 1/4 turn CCW
Shift bang... check header bolts, muffler clamp or header gasket
Engine braking grumble pop... enjoy!

87 Just like the Suzuki book tells us, more energy per unit you know,for the record my bike almost never backfires, by the way grumble pops are not backfires just a great  motor letting you know it's there. Love this ride for what it is.

Using higher octane than 87 does two things for you.  1. Makes your wallet thinner.  2. Makes your bike get less mileage and possibly less power.

The only time using a higher octane would help is when there is something wrong with the bike and it detonates (pings) on lower octane.

I switched from 89 to 87. First tank ... no change in mpg (50) or performance. We will see what the second tank brings.

I do get more backfires, obviously because of the change in the flash point of the fuel. These pipe farts consist of both pops and outright bangs. They occur when I disengage the clutch and roll free, when the engine is backing down from higher RPM to idle RPM. Lets the traffic know I am there. I am just a little bit concerned, however, that this backfiring behavior may damage something. I blew a glass pack right off my old hot rod nearly 50 years ago! Anybody think the backfires will harm the Suzy (06 S40)?

Ah, well. I hear the carb screws on these bikes are plugged, so I would have to drill out the plug before I could adjust that ... at least that's what I hear. I have also heard that it is real easy to drill into the screw while drilling out the plug, and then you buy a new carb. I would tend to leave the mixture alone if I am keeping it stock, since the manufacturer seems to intend that it be mixed that way. My 150cc Kymco scooter did the pop-pop routine until a mechanic set the valves correctly. So, I wonder if the backfire on the Suzy could be caused by valve setting (bike runs great). I also wonder if the carb might be a little dirty. My bike sat up for a number of years before I bought it, with 1200 miles on it. Is is kosher to use some kind of carb/FI cleaner in the fuel? Wonder if that might help. I hear talk about Sea Foam, but I don't know what that is.

J2 wrote on 10/04/10 at 08:09:30:


J2, the adjuster is behind a plug, but it is not too hard to get it out.  I even did it, with no damage. (Ride out my way and we will drill that plug out, if you want.)  I have not heard anyone say the popping had anythign to do with the valves, but who knows.  It seems the consensus is our bikes run lean from the factory, to meet the EPA guidelines.  Carb cleaner would be fine, I am sure.  seafoam is a fuel additive, carb cleaner wonder product that some love   and some hate  It certainly won't hurt anything, you can get it from wal-mart or about any other parts place.  I have used it through my bike, maybe it helped a little, i think so, but that is just my perception.

Thanks for the info. Washington NC would be a nice ride from Raleigh. Might take you up on that.

For all yall who don't speak Nawth Karolinian, we be awl good neighbors rown heah ... just like Andy ... and the county mounties are just like Barney. Yall come see us, ya heah!