Backfire "Pop" When Engine Shuts Off - Normal?

[Dirt_McGert]

Whenever I get done riding and turn the key off, the motor slows, and a half a second after everything seems to stop, a fairly loud "pop" comes out of the exhaust. It's not extremely loud, but it has a nice "pop" sound to it.

What is it, and how come it happens? Is it normal? If not, how can I fix it?

Thanks!!

[Dupo]

Sounds like advanced timing .... just like on a car. Do you have the service manual for the bike? If not, download it from this forum (check the stickies in general)

[Dirt_McGert]

Yep, I just downloaded it earlier today. I'll check it out when I have time, it's not a big deal, just kinda annoying when I turn it off.

[Dupo]

I'd go right to the section on timing. That should fix the problem right up

[Dirt_McGert]

Hmmm, I didn't find a specific section on the timing, just that it's controlled by the ignitor.

[Badbob]

I could be wrong?

I don't think the timing is adjustable.

The fully transistorized ignition system consists of the following components: a generator, ignitor, igni-tion coil and spark plug. The ignition timing is programmed and stored in the ignitor. The pick-up coil is mounted in the generator. The induced signal in the pick-up coil is sent to the wave-form arrangement circuit and the CPU receives this signal and calculates the best ignition timing. The CPU outputs the signal to the transistor of the ignition coil output circuit which is connected to the primary windings of the ignition coil which is turned "off" and "on" accordingly. Thus, it induces the secondary current in the ignition coil's secondary winding and produces the spark between the spark plug gap.

[Dirt_McGert]

Yeah, that's what I found....

[Dupo]

Hm, well i guess its not adjustable then. Maybe the ignitor then??

[Dirt_McGert]

Just to add to the advanced timing possibility, when I rev the engine pretty high and then let off the throttle, it sometimes lets out a few minor pops, but they aren't very noticible. This is probably normal, and it's not a big deal to me, unless something mechanically is off.

[Dupo]

See your other post that i answered, might be crapped up in the carbs from sitting.

I think you might want to get it checked for the over running its doing when shut off, unless the seafoam i suggested in the other post clears it up.