Motorcycle Repair: Intruder (800) gasoline and backfires, pow pow pow, intruder 800

Question
Hey, Mark.

   My 1997 was wrecked, and rebuilt.  Ever since, it seems to backfire whenever I let off the gas under load (squeeze the clutch and let off, it rarely backfires, but leave the clutch engaged, and Pow Pow Pow...).  The shop that rebuilt it did a decent job, but I don't think they really knew suzukis.  Anyway, I am using midgrade gas (89 octane) and was wondering if I should go with the high grade, but don't want to "mess it up" by using the wrong stuff.  So, 2 part question:   What grade SHOULD I be using, and what suggestions do you have for getting rid of the back fires?  Note:  does not matter, warm or cold, it backfires.

Thanks!

Answer
Hi Eric,

I suspect the air cut-off diaphragms are defective. These diaphragms are used to reduce or eliminate backfiring, especially on deacceleration.

To see the parts visit the following website and look at part #30.

http://houseofmotorcycles.bikebandit.com/partsbandit/oem_schematic_view.asp?sche...


This may or may not be the problem. This is where I would look first.

Use the lowest grade octane or that specified in the owner's manual. Octance was a concern with leaded gasolines causing engine knocking (detonation). Those days are history. Why pay more?

Respectfully,
Mark Shively