SuzukiSavage.com - Backfire + choke = ??

DrunkenDwarf Senior Member Offline Morning Zombie Posts: 325 Seattle, WA Gender:	Backfire + choke = ?? 05/13/09 at 06:51:18 I definitely have an exhaust leak. The oil inspection window is covered in soot. Ignore that for now. This morning on the way to work I noticed that when my choke was out one notch and I closed the throttle, it didn't backfire. As soon as I closed the choke it would backfire on throttle close. Can someone explain to me the relationship? -D. Dwarf
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SavageDanny

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Re: Backfire + choke = ??
Reply #1 - 05/13/09 at 07:05:04

Someone might correct me on this but I think the choke is not actually a choke. It's and enricher (spelling?). Provides a little extra fuel on start up. I have heard the bike runs lean on the factory settings. If I understand it correct most of the carb mods generally make the bike run richer. When I tuned mine to run a little richer it quit most of the backfiring.

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Re: Backfire + choke = ??
Reply #2 - 05/13/09 at 07:13:30

I have the same problem with mine on the oil inspection window. I can feel the exhause leak however it isn't where anything connects. Have you pulled the brass plug and adjusted the idle mixture screw to get ride of the backfire. Start at 1/4 turn at a time and give throttle to test. I recently did the white spacer mod, put a new muffler on with a stage 2 jet kit and cone filter. Very happy with the results and it sound almost like a Harley with better mid range pickup and top end speed. Still get back fire at times but I think it's cuz of the exhaust leak. Shocked

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DrunkenDwarf Senior Member Offline Morning Zombie Posts: 325 Seattle, WA Gender:	Re: Backfire + choke = ?? Reply #3 - 05/13/09 at 07:26:07 Step 0) Previous owner rejetted (0.055/0.155) and installed Dyna Step 1) Fix Exhaust leak Step 2) Do white spacer mod Step 3) Adjust Idle Step 4) Ride Just curious what the relationship between a richer mixture and a backfire is. -D. Dwarf
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Re: Backfire + choke = ??
Reply #4 - 05/13/09 at 07:30:53

DrunkenDwarf wrote on 05/13/09 at 07:26:07:

Just curious what the relationship between a richer mixture and a backfire is.

Same as lean mixture, except you're dumping extra fuel all the time.

With lean, a bad burn leaves extra fuel in the exhaust till it hits fresh air and kapow.
With rich, just about every burn leaves a little.

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DrunkenDwarf

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Re: Backfire + choke = ??
Reply #5 - 05/13/09 at 09:29:46

verslagen1 wrote on 05/13/09 at 07:30:53:

DrunkenDwarf wrote on 05/13/09 at 07:26:07:

Just curious what the relationship between a richer mixture and a backfire is.

Same as lean mixture, except you're dumping extra fuel all the time.

With lean, a bad burn leaves extra fuel in the exhaust till it hits fresh air and kapow.
With rich, just about every burn leaves a little.

But the relationship I noticed was that a richer mixture ("choke" out 1 notch) backfired less.

Would that imply that in some segment of the throttle I'm lean and the choke brings it up to normal?

-D. Dwarf

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marshall13

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Re: Backfire + choke = ??
Reply #6 - 05/13/09 at 09:38:29

DrunkenDwarf wrote on 05/13/09 at 09:29:46:

verslagen1 wrote on 05/13/09 at 07:30:53:

DrunkenDwarf wrote on 05/13/09 at 07:26:07:

Just curious what the relationship between a richer mixture and a backfire is.

Same as lean mixture, except you're dumping extra fuel all the time.

With lean, a bad burn leaves extra fuel in the exhaust till it hits fresh air and kapow.
With rich, just about every burn leaves a little.

But the relationship I noticed was that a richer mixture ("choke" out 1 notch) backfired less.

Would that imply that in some segment of the throttle I'm lean and the choke brings it up to normal?

-D. Dwarf

kinda.... it means you get bad burns, and enrichening a bit helps at times.... only plug deposits for different throttle opening ranges can actually tell you what's happening when.... ill bet tossing in a real CDI would go a long way to eliminating backfire... yeah, i though these had CDI iggy's too, but they dont... check the wiring diagram in the clymer... batt voltage to coil (ign. hot goes to coil)... cant do that with a CDI, or you'd get a 500 volt spike back through your primary system.....

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