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  #1  
Old 03-02-2021, 01:36 PM
Champ's Avatar
Champ Champ is offline
 
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Location: Kingsville, Ontario, Canada
Posts: 320
Default Air Filter Damage

I had a dirty injector, cleaned it and did another GAMI Lean test using Savvy's procedure. The lean test came out good with .4 GPH spread. However at the end of the 3rd run I also did an in-flight mag check. I was aggressively leaned at this point and heard what I thought was a cylinder missing on both the Left & Right mags (a little worse on the Right).

On my walk around today I saw this on my intake filter.
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Name:	Air Filter Damage.jpg
Views:	148
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ID:	8967

It looks more like a backfire than a cylinder miss. Is it possible to get a backfire in a situation like this?

I'll be ordering a new filter K&N 33-2060.
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  #2  
Old 03-02-2021, 02:34 PM
Bavafa Bavafa is offline
 
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Location: Sacramento, CA
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Default

Quote:
Originally Posted by Champ View Post
I had a dirty injector, cleaned it and did another GAMI Lean test using Savvy's procedure. The lean test came out good with .4 GPH spread. However at the end of the 3rd run I also did an in-flight mag check. I was aggressively leaned at this point and heard what I thought was a cylinder missing on both the Left & Right mags (a little worse on the Right).

On my walk around today I saw this on my intake filter.
Attachment 8967

It looks more like a backfire than a cylinder miss. Is it possible to get a backfire in a situation like this?

I'll be ordering a new filter K&N 33-2060.
Is it electronic Mag or slick? I am not sure if .4 GPH spread is all that good. The aim is for .2G or less. but to I think it is possible to have back fire in those condition depending on power setting, advance timing.
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  #3  
Old 03-02-2021, 06:53 PM
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Scott Chastain Scott Chastain is online now
 
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Default

Quote:
Originally Posted by Champ View Post
It looks more like a backfire than a cylinder miss. Is it possible to get a backfire in a situation like this?
Yes. It can happen easily on a kickback as in my case about 10 years ago. It only happened once, and I promised not to let it happen again. Keep that starter engaged until you have a clean start. My guess that your filter suffered a backfire during one of your startups, but you didn't notice the filter until after the GAMI test.



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Last edited by Scott Chastain : 03-02-2021 at 07:00 PM.
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  #4  
Old 03-02-2021, 07:27 PM
wnplt wnplt is offline
 
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Location: Idaho
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Default

Ive had a couple hot start backfires that did that. Now I never have the throttle full open on a hot start. I hot start with throttle closed and butterfly in servo keeps it from backfiring in the airbox blowing out the filter. Haven't had to replace one since. Basically my hot start is throttle closed and mixture idle cutoff and then slowly add mixture as it catches.
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  #5  
Old 03-02-2021, 07:53 PM
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Default

A start up backfire makes sense. It could have happened on a less careful recent start where I let off cranking before I got a clean start. I start with the throttle cracked and mixture at ICO and advance on firing. I'll have to try a throttle closed start and make sure I keep the starter engaged.

Bavafa - I have had .2 GPH spread on previous GAMI tests. I have dual P-Mags.

Thanks everyone.
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  #6  
Old 03-02-2021, 08:04 PM
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emsvitil emsvitil is offline
 
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I thought K&N filters were free-flow........

Shouldn't a blast just flow right thru it ?
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  #7  
Old 03-03-2021, 12:08 AM
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Quote:
Originally Posted by emsvitil View Post
I thought K&N filters were free-flow........

Shouldn't a blast just flow right thru it ?
Ed, not sure if you are kidding or not, but even a bug screen would be deformed during a backfire.
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  #8  
Old 03-03-2021, 12:20 AM
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Forgot this:

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  #9  
Old 03-03-2021, 12:43 AM
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Forgot this:

got it!
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  #10  
Old 03-03-2021, 03:12 AM
Hwood Hwood is offline
 
Join Date: Feb 2005
Location: Central Alabama
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Default Just a thought...

You may want to take a look at your snorkel and assess it's condition. I had a startup fart once (which at the tome didn't think it was too bad) but later found the snorkel had about an 8" split from the back pressure.

No big deal to fix it but you gotta find it first!
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