SuzukiSavage.com - no change after white spacer mod

dabid

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no change after white spacer mod
04/14/13 at 15:44:51

Hey guys,

I just replaced the white spacer with the three washers supplied in Lancers kit.

I have a stock airbox and filter, with the blue collar bobbers exhaust (straight pipe with baffle inside)

When i shut off the bike, I still get a loud gunfire pop, sometimes it takes as long as 5 or 6 seconds after.

I am running a 52.5 pilot and 150 main.

Why am I still getting the super loud backfire?

thanks!

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rfw2003 Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 1108 Yantis, TX	Re: no change after white spacer mod Reply #1 - 04/14/13 at 15:51:45 Have you checked all exhaust connections to make sure there are absolutely no leaks. Do this with a candle if you have to, to make sure. A leak on any of the connections is one of the biggest causes of the shotgun blasts on shutoff and during shifts. R.F.
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apache snow-FSO Serious Thumper Offline Posts: 509 Gender:	Re: no change after white spacer mod Reply #2 - 04/14/13 at 15:52:36 When I went to a 55 pilot mine got better with the muffler farts. The needle only controles from 1/4 to 3/4 throttle (midrange) although there is some overlap. How many turns out is your fuel screw?
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Serowbot YaBB Moderator ModSquad Offline OK.... so what's the speed of dark? Posts: 28644 Tucson Az Gender:	Re: no change after white spacer mod Reply #3 - 04/14/13 at 17:16:48 It may be that the pipe is just too open... In which case,.. you basically just have too jet it rich enough, that it runs bad enough, that the exhaust temps won't ignite fuel... and instead, it will just dribble fuel out back end... That's the only way I can figure that some members are getting mpg's in the 30's... ...
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apache snow-FSO Serious Thumper Offline Posts: 509 Gender:	Re: no change after white spacer mod Reply #4 - 04/14/13 at 17:24:05 With three washers you did not raise the needle that much. I would try two washers and find out where I was on the pilot.
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engineer

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Re: no change after white spacer mod
Reply #5 - 04/14/13 at 18:52:11

I don't think a delayed back fire after you shut off the engine is caused by the same thing as the back fires people get while running and backing off the throttle.

For a delayed backfire to occur after shut off you need the same three things you always need for combustion, fuel, air, and a source of ignition. Sometimes fuel can build up, then as the exhaust begins to cool a leaky joint can suck in air or maybe there is a decent fuel air mix already in there from a quick shut down, and some existing hot spot, maybe a glowing piece of carbon that has built up, sets off the bang.

Letting it idle down for a while might help, it often does with lawn tractors that have a delayed pop. Making certain there are no exhaust leaks might help. The two nuts on my manifold studs were loose. Beyond those two easy things it gets more complicated. I'm still working on the same problem and I'm hoping you'll get an answer.

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Dave

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Re: no change after white spacer mod
Reply #6 - 04/15/13 at 04:54:31

The washers and needle have nothing to do with the pop on shut down. The needle affects the mixture from about 1/4 throttle to about 3/4 throttle. Changing the needle by removng washers will richen the mix up, and will be most noticeable as you slowly open the throttle to accelerate.....if you get a hesitation or lurching you need to be a bit richer.

The "afterfire" upon shut down is caused by the fact that you have turned off the ignition - and as the engine is spinning it is pumping unburned fuel and air into the hot exhaust pipe. When the unburned fuel and air are heated by the exhaust pipe - they can reach a temperature that will cause them to ignite....and POOF!

I do believe that a rich mixture in the exhaust will "poof" while a lean mixure will "POW"....and that it is the fuel mixture at idle that controls this isue (pilot jet and idle mixture screw).....it is not the needle or washers.

I would jet your engine in a way that it runs good - and let your engine idle for 20-30 seconds before you shut it down and see if that helps any.

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gdrseeker

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Re: no change after white spacer mod
Reply #7 - 04/15/13 at 08:37:24

I found that shutting the bike off correctly after letting it idle for about 10 seconds helps.

To shut off correctly 1) Pull up to parking space, 2) Put bike in neutral, 3) Put kickstand down, 4) Idle for 10 seconds, 5) Turn key to the off position.

DON'T

Use the engine kill switch.
or
Put the kickstand down in gear to kill the engine.

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apache snow-FSO Serious Thumper Offline Posts: 509 Gender:	Re: no change after white spacer mod Reply #8 - 04/15/13 at 08:50:59 Key, kill switch, and kick stand all cut off the fire to the spark plug. The spark plug doesn't care which one does it.
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dabid

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Re: no change after white spacer mod
Reply #9 - 04/15/13 at 08:58:53

Ok,

So I am going to double check for exhaust leaks.

I will take her for a spin to get the motor nice and warm, and then try a proper shut down. I usually just pull up and hit the kill switch. I will try the 10-20 second idle and see what happens.

It is such a huge pain to keep taking the carb on and off, i have the Blue collar bobber kit which makes taking the tank off a real pain.

On a side note, I am adding a K&N in a week or so, so I might need to go up size on my pilot jet.

Ill update after today.

thank you everyone for the help!!

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dabid

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Re: no change after white spacer mod
Reply #10 - 04/15/13 at 09:05:23

apache snow-FSO wrote on 04/14/13 at 15:52:36:

When I went to a 55 pilot mine got better with the muffler farts.

The needle only controles from 1/4 to 3/4 throttle (midrange) although there is some overlap.

How many turns out is your fuel screw?

I have the Fuel screw at 2 turns out. Maybe I will richen it up a bit around 2.5 turns and see what happens.

Thanks for the Help!!

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paulmarshall Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 1268 Carterton,New Zealand Gender:	Re: no change after white spacer mod Reply #11 - 04/15/13 at 11:31:38 DON'T Use the engine kill switch. or Put the kickstand down in gear to kill the engine. [Whats wrong with using the Kill Switch when shutting down our engines?]
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Re: no change after white spacer mod
Reply #12 - 04/15/13 at 11:55:03

+1 Dave on the cause of the after ignition shut down pop. If this engine was fuel injected, no more fuel would be dumped into the combustion chamber after ignition shut down. The electrical pulse to the injectors would be stopped and no more fuel dumped into the combustion chamber. The spinning down of the carbureted engine fills the exhaust pipes with the same air fuel mixture dumped into the combustion chamber during the idling ignition on stage, even though the ignition is turned off. The delay in ignition of this unburned fuel mixture is caused by the migration backwards to the hottest spot in the exhaust system near the begining of the exhaust pipe. If you want to hear a louder shut down pop, just turn off the ignition key at a higher RPM. At night you can see flames coming out the exhaust pipe and the sound is similsr to a gun going off.

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Re: no change after white spacer mod
Reply #13 - 04/15/13 at 12:05:30

gdrseeker wrote on 04/15/13 at 08:37:24:

I found that shutting the bike off correctly after letting it idle for about 10 seconds helps.

To shut off correctly 1) Pull up to parking space, 2) Put bike in neutral, 3) Put kickstand down, 4) Idle for 10 seconds, 5) Turn key to the off position.

DON'T

Use the engine kill switch.
or
Put the kickstand down in gear to kill the engine.

Being one to nearly always use the kill button to 'kill' it... why is one switch better than the other?

Are you afraid of wearing them out?

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apache snow-FSO

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Re: no change after white spacer mod
Reply #14 - 04/15/13 at 12:08:16

paulmarshall wrote on 04/15/13 at 11:31:38:

DON'T

Use the engine kill switch.
or
Put the kickstand down in gear to kill the engine.

[Whats wrong with using the Kill Switch when shutting down our engines?]

The only problem I have using the kill switch is I leave it on and the next time I try to start the bike I wonder why it won't start. Shocked

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