I got bad gas?

[bikernana]

Last weekend hubby and I went on a ride to Olympia, Tumwater, and then back home to Shelton. I ride a Suzuki 40 which is known for backfiring. OK, usually it backfires when I turn off the motor; but this time, it was doing it whenever I gave it less gas. Not all the time, but sometimes. I'm afraid that if I rode it to the wrong part of town, some people may think it's gun fire and start firing (Just an exaggeration but want you to get the picture.) So my question is this, I put regular gas in it; my hubby said I may want to try the middle grade if it was BF alot; I want to know is my hubby right? Will using the middle grade gas help the backfiring? Thanks for you responses.

[Skier]

If it was after-firing through the mufflers, commonly called backfiring, it's due to unburned fuel igniting after passing through the combustion chamber and into the exhaust. Using a higher octane fuel, which is harder to ignite, won't solve anything.

Use the fuel octane recommended in your owner's manual.

If the excessive after-firing stops after your next tank, you can write it off as bad fuel. Otherwise look for mechanical issues.

[flynrider]

Skier is correct. The octane rating of the gasoline will have no effect on backfiring. The S40/Savage is well known for popping through the pipes when you let off the throttle. It has an ultra lean mixture setting on the carb, which is primarily responsible. If it's also doing it whenever you turn off the bike, that would seem to be a bit excessive. I'd recommend having your valve clearances checked.