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Message started by shovelbum87 on 06/18/13 at 15:47:24

Title: Why does my bike backfire when I shut it down?
Post by shovelbum87 on 06/18/13 at 15:47:24

Every time I shut my bike off she gives a pop, do I have my idle air mix off?

Title: Re: Why does my bike backfire when I shut it down?
Post by WD on 06/18/13 at 16:13:10

Yep, just like the factory does. Go out 1/4 turn at a time until it calms down if it bothers you, otherwise ignore it, it's normal.

Title: Re: Why does my bike backfire when I shut it down?
Post by shovelbum87 on 06/18/13 at 16:15:35

If its normal im ok with it, I just wanted to make sure that I didnt mess it up too much. We had a little issue with a stripped air fuel screw... had to flat bottom drill it and then put a new head on it so I was concerned that I pulled it out too far... I think its funny!

Title: Re: Why does my bike backfire when I shut it down?
Post by Dane Allen on 06/18/13 at 16:56:05

5942455C4F46485F47121D2A0 wrote:

I was worried about it to, we experienced a work related shooting last year and I just cringe every time I pull up to motorcycle/carpool parking (next to the front doors, of course), shut down and POW!! I know I could fiddle with the screw but that is a signature sound of the big thumper.

Who am I to quiet the cry of a victorious travel? ;D Seems the louder the more people are around going into the office.

Maybe I should ease the screw just a bit, for careers sake... ;D ;D ;D

Title: Re: Why does my bike backfire when I shut it down?
Post by engineer on 06/18/13 at 19:29:55

Turn the air screw about 1/8 or 1/4 turn open beyond the optimal setting (the setting where it idles fastest). I did it with a little coaching from the team here and got rid of the after fire. A little idle time prior to shutting it down also helps.

I hated the after fire. All the nosey neighbors knew when I was getting home. Now they will at least have to peek out the window since I no longer announce my return with a shot gun blast.

Title: Re: Why does my bike backfire when I shut it down?
Post by Serowbot on 06/18/13 at 23:33:34

I backfire when I shutdown...

I just figured me and my bike were bonding... :-?...

Title: Re: Why does my bike backfire when I shut it down?
Post by jcstokes on 06/19/13 at 04:24:45

Some say check the exhaust pipe header bolts as well.

Title: Re: Why does my bike backfire when I shut it down?
Post by Dave on 06/19/13 at 04:53:55

When you turn off your ignition the engine is still turning and is sill pulling air through the carb.....where it picks up fuel the same as if it were idling. Since the ignition is off....the fuel/air mixture just gets pumped through the engine and into the hot exhaust system. When the temperature of the fuel air mixture is elevated by the hot exhaust system.....it can become hot enough to spontaneously combust in the exhaust pipe and "bang". Leaner mixtures seem to make a louder pop than a rich mixture. I believe you should adjust the mixture screw for the best engine operation.......not to eliminate backfires or afterfires.

Title: Re: Why does my bike backfire when I shut it down?
Post by Pine on 06/19/13 at 06:41:18

1C272A3D2C203B3D262E233C4F0 wrote:

When you turn off your ignition the engine is still turning and is till pulling air through the carb.....where it picks up fuel the same as if it were idling. Since the ignition is off....the fuel/air mixture just gets pumped through the engine and into the hot exhaust system. When the temperature of the fuel air mixture is elevated by the hot exhaust system.....it can become hot enough to spontaneously combust in the exhaut pipe and "bang". Leaner mixtures seem to make a louder pop than a rich mixture. I believe you should adjust the mixture screw for the best engine operation.......not to eliminate backfires or afterfires.

I believe you should adjust the mixture screw for the best engine operation.......not to eliminate backfires or afterfires.

/agree

I choose not to adjust the carb to eliminate backfires... but I have a sequence that I use to virtually eliminate the issue.. or at least reduce it to a mere phoot...

When getting ready to shut down:
Stop the bike,
reach down and pull out the "choke" ( it isn't really)
Half generally works but full out if needed
when you first do this the RPMs will drop
while the rpms are down, use the kill switch to shut down
Remember to push the choke back in
Remember to return the kill switch
Always park in gear ( generally 1st)

The bike requires a high idle to maintain proper lubrication to the head, but when shutting down the high idle allows as described above (intake of gas rich air mixture ) which is then shoved out a very hot exhaust. Other possible contributing factors:
Fresh air leaking into exhaust manifold at the head, allows for leaner and O2 rich condition in the manifold. Check the header bolts. I have read here that sharp edges inside the muffler absorb the heat and can create the "hot ember" needed to ignite the gases in the muffler. I suspect that over time this would be more common as components break down.

Title: Re: Why does my bike backfire when I shut it down?
Post by old_rider on 06/19/13 at 11:29:27

I did both the air screw mixture setting and the white spacer change out to two small washers. I occasionally get a "poof" sound on shut down, but thats only if I shut down right away, if I let it idle for more than 20 or 30 seconds (slow idle) it hardly ever poofs, but I don't get pops anymore on shutdown, just on downshifing.

Title: Re: Why does my bike backfire when I shut it down?
Post by Dane Allen on 06/19/13 at 12:06:40

665D5047565A41475C545946350 wrote:

Thanks soo much for this and I agree!! Do you mind if I provide a copy of this reponse to HR? ;)

Title: Re: Why does my bike backfire when I shut it down?
Post by shovelbum87 on 06/19/13 at 16:02:11

I just wanted to make sure I didnt eff something up during my tinkering, If we all say its normal then like I said I think its kinda funny... Reminds me of a horse I had when I was younger. She used to squeal at me everytime I dismounted. Maybe I will call the savage Abbey after my horse.

Title: Re: Why does my bike backfire when I shut it down?
Post by Dave on 06/19/13 at 18:48:06

587D72795D707079721C0 wrote:

[quote author=665D5047565A41475C545946350 link=1371595644/0#7 date=1371642835]When you turn off your ignition the engine is still turning and is till pulling air through the carb.....where it picks up fuel the same as if it were idling. Since the ignition is off....the fuel/air mixture just gets pumped through the engine and into the hot exhaust system. When the temperature of the fuel air mixture is elevated by the hot exhaust system.....it can become hot enough to spontaneously combust in the exhaut pipe and "bang". Leaner mixtures seem to make a louder pop than a rich mixture. I believe you should adjust the mixture screw for the best engine operation.......not to eliminate backfires or afterfires.

Thanks soo much for this and I agree!! Do you mind if I provide a copy of this reponse to HR? ;)[/quote]

Who/what is HR?

Go ahead and use what you want.....

Title: Re: Why does my bike backfire when I shut it down?
Post by MiCTLaN on 06/19/13 at 20:55:39

A: Because it's a Savage.

Title: Re: Why does my bike backfire when I shut it down?
Post by Dane Allen on 06/20/13 at 13:19:06

4B707D6A7B776C6A7179746B180 wrote:

[quote author=587D72795D707079721C0 link=1371595644/0#10 date=1371668800][quote author=665D5047565A41475C545946350 link=1371595644/0#7 date=1371642835]When you turn off your ignition the engine is still turning and is till pulling air through the carb.....where it picks up fuel the same as if it were idling. Since the ignition is off....the fuel/air mixture just gets pumped through the engine and into the hot exhaust system. When the temperature of the fuel air mixture is elevated by the hot exhaust system.....it can become hot enough to spontaneously combust in the exhaut pipe and "bang". Leaner mixtures seem to make a louder pop than a rich mixture. I believe you should adjust the mixture screw for the best engine operation.......not to eliminate backfires or afterfires.

Thanks soo much for this and I agree!! Do you mind if I provide a copy of this reponse to HR? ;)[/quote]

Who/what is HR?

Go ahead and use what you want.....[/quote]

;D ;D ;D Human Resources ;)