hesitation and back fires

[weiser23]

when down shifting my bike seems to be back firing alot more and when when you get back on the throttle it hesitates , if completely stopped sometimes it stalls. I was coming to a stop sign almost stopped and starting to turn i hit the throttle the engine stalled and the bike hit the ground and I was scrambling to get the bike back up before anyone saw ;three week ago I had a new spark plug air cleaner and what ever the first service gets

[FastDoc]

Glad you and the bike are OK.

Please remind us. You ride a Q? What modifications if any?

[SpudRider]

Glad you and the bike are OK.

Please remind us. You ride a Q? What modifications if any?
X2 on all points.

Spud :)

[weiser23]

09 qlink stock, when I say back fire I dont mean not real loud just popping most of the time, but under bridges its pretty loud

[SpudRider]

Perhaps the main jet in your carburetor is too rich. At what elevation are your riding, and what is the size of your current main jet?

Spud :)

[weiser23]

Perhaps the main jet in your carburetor is too rich. At what elevation are your riding, and what is the size of your current main jet?

Spud :)

im not sure what ever the stock bike has on it

[FastDoc]

I don't recall a misjetted, much less rich Q ever in factory configuration. Plugged air filter maybe?

[Weldangrind]

Maybe the reed valve in the smog device (if equipped) isn't seating. That would allow too much oxygen to hit the exhaust.

[weiser23]

[quote="Weldangrind"]Maybe the reed valve in the smog device (if equipped) isn't seating. That would allow too much oxygen to hit the exhaust.[/quo

thanks for the tip what can i do about that

[Weldangrind]

Toss it in the trash and make a block-off plate, unless you live in the PRK. If your municipality or State requires that you keep such a ridiculous device, then get crafty about disabling it.

Once removed, the catalytic converter could be removed as well.

[martin556310]

My bike was cutting out and misfiring in the high gears and would random stall at stops. I replaced the CDI box (under the seat) and it fixed it. The part was cheap, but make sure you get the correct connector type.

[SpudRider]

My bike was cutting out and misfiring in the high gears and would random stall at stops. I replaced the CDI box (under the seat) and it fixed it. The part was cheap, but make sure you get the correct connector type.
I agree. ;) These symptoms might also indicate a bad CDI unit. It's always a good idea to have a spare CDI unit on hand. The spare CDI unit greatly facilitates the troubleshooting of electrical problems. Also, if your CDI unit fails, you can plug in the spare, and go riding, rather than wait for a new one to arrive. :)

Spud :)

[Weldangrind]

I agree that a bad CDI can cause misfiring, but this symptom is more likened to back-firing, if I'm understanding correctly. My leading theory is still that it's an air / fuel issue, however it's caused.

[SpudRider]

I agree that a bad CDI can cause misfiring, but this symptom is more likened to back-firing, if I'm understanding correctly. My leading theory is still that it's an air / fuel issue, however it's caused.
I agree. ;) The cause is most likely an air/fuel issue. However, it's always a good idea to have a spare CDI unit handy. For example, in this particular instance, substituting the CDI unit could help rule out electrical problems as a contributing factor. ;)

Spud :)

[bigheavy150]

Idle jet can be lean. These bikes dont have accelerator pumps to give that extra shot of gas when you open throttle quickly.This leaves you with a 1/10th second of very lean mixture. not a problem if its correct to begin with but your idleing with a hot motor and you jump on the gas giving the motor a big gulp of fresh air but still that tiny idle jet of fuel, then the fuel begins to get sucked out the jets like its supposed to.

We are dealing with really tiny motors, they can be real picky about carburation...

check your idle screw settings.maybe go 1/2-3/4 turn out. what altitude are you at?