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  #11  
Old 10-29-2019, 09:12 PM
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roadrunner20 roadrunner20 is offline
 
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Update:
I have continued to get kickbacks with the light priming suggestions.
Is it due to my light prop? Need to retard timing?

I'm not interested in testing the retard timing option.
Before I do any damage to my starter, I've decided to go back to my dual slick mags. I've had 13 years of no kickbacks & a reliable starting system.

Thanks you for your suggestions.
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  #12  
Old 10-29-2019, 09:41 PM
Robin8er Robin8er is offline
 
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I also have a light wood prop and had the same issue. My start procedure is:

1) ensure ignition, mixture and fuel is off

2) rotate the prop slowly and let the pressure bleed off from the compression stroke.

3) start the plane as normal.

Getting the compression out seems to help drastically with kick back. It always seems like the first rotation is where I had issues from not having enough momentum to swing the prop, resulting in kick back. I started doing this after I broke a starter from the same issue. Since I've started doing this I haven't had any kick back.

Be super careful when doing this, you don't want to accidently hand prop it!
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  #13  
Old 10-29-2019, 09:44 PM
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Quote:
Originally Posted by Robin8er View Post
I also have a light wood prop and had the same issue.
Getting the compression out seems to help drastically with kick back. It always seems like the first rotation is where I had issues from not having enough momentum to swing the prop, resulting in kick back. I started doing this after I broke a starter from the same issue. Since I've started doing this I haven't had any kick back.
Yes. My kickbacks were always on the first rotation too.
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  #14  
Old 10-30-2019, 07:21 AM
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We get comments pretty frequently about kickbacks with a couple of popular EI brands. Assuming you have the EI set as per manufacturer's instructions, a good battery and starter to swing the prop smartly, the cause is simply not enough retard during cranking. This is really a software issue which in itself, shows a lack of testing before product release.

A marginal battery or starter can cause overly advanced ignition timing while cranking as the crank slows locally as it comes up on compression.
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  #15  
Old 10-30-2019, 08:25 AM
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M McGraw M McGraw is offline
 
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Quote:
Originally Posted by roadrunner20 View Post
.....

Surefly suggested I look at the voltage at starter to insure > 10V
My starter voltage is 12.8/12.9 volts.


FWIW, I've checked & rechecked timing to above.
The most likely issue is a lack of proper retard during starting; however, 12.8/12.9 volts at the starter seems unusually good. Is that the voltage UNDER LOAD during the start?
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  #16  
Old 10-30-2019, 08:48 AM
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10V under starter load is a good number so that is not the issue. The only way you can get kickbacks is if ignition happens too far BTDC.
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Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 436.1 hrs. on the Hobbs,
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http://www.sdsefi.com/aircraft.html
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  #17  
Old 10-30-2019, 08:53 AM
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Quote:
Originally Posted by M McGraw View Post
The most likely issue is a lack of proper retard during starting; however, 12.8/12.9 volts at the starter seems unusually good. Is that the voltage UNDER LOAD during the start?
No. This was not under load. Since Iíve never experienced a load issue, I didnít pursue it further. Not a tired battery either as it was replaced 6 months old.

Thank you all for your input.
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  #18  
Old 10-30-2019, 08:55 AM
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Does the surefly have a method to alter the start retard timing during configuration setup? The SDS products are user configurable and mine is set to fire 3 degrees AFTER top dead center any time the starter is engaged. This means there is no way to get a kick back no matter the prime, start technique, weight of the prop, etc. I know some other ignition products have a start retard functions as well, but it's only engaged on the first revolution of the prop. If it doesn't catch the first time, you need to cycle the ignition off and on to reset the retard. Is the surefly like this?
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  #19  
Old 10-30-2019, 08:57 AM
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Quote:
Originally Posted by roadrunner20 View Post
No. This was not under load. Since Iíve never experienced a load issue, I didnít pursue it further. Not a tired battery either as it was replaced 6 months old.

Thank you all for your input.
Battery condition does not ensure that the starter is seeing the proper voltage. Need to test this under load. Easy to do and could very well be your issue.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

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  #20  
Old 10-30-2019, 09:00 AM
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roadrunner20 roadrunner20 is offline
 
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Quote:
Originally Posted by Toobuilder View Post
Does the surefly have a method to alter the start retard timing during configuration setup? The SDS products are user configurable and mine is set to fire 3 degrees AFTER top dead center any time the starter is engaged. This means there is no way to get a kick back no matter the prime, start technique, weight of the prop, etc. I know some other ignition products have a start retard functions as well, but it's only engaged on the first revolution of the prop. If it doesn't catch the first time, you need to cycle the ignition off and on to reset the retard. Is the surefly like this?
No option to retard timing.
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