Gearing down sound change

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Apr 23, 2013 | 01:48 AM

ke5rbd

Thread Starter

Road Warrior

Joined: Apr 2010

Posts: 1,648

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From: Monroe, Louisiana

Gearing down sound change

Has anyone besides me noticed when gearing down/engine braking the engine changes sound about 1800 rpms and just sort of releases the engine braking. I have a 2010 FLHTK that has done it since I bought it new. Have rode other bikes and they do the same thing. I am not going to leave you in suspense as I finally discovered today what causes it. I have my Power Vision mounted on handle bars and am using the gauge function with the 6 digital gauge template. I have Front and rear VE and timing showing. I decided to watch it and see if I could catch what was happening. Sure enough when it got to about 1800 the timing went from around 25 degrees to 0 degrees for about 1/2 second and that is when it did it. It has a separate timing map for idle which is set to 25 degrees and I guess it is transitioning between the two. It also gives a very slight double pop at the same time, so it makes me believe it stops firing for a revolution too.

Apr 23, 2013 | 02:10 AM

agedwards63

Road Master

Joined: Jan 2007

Posts: 810

Likes: 1

From: East Alton IL

I just assumed it was the 6 Speed Tranny none of my five speed Harleys did it but yeah I hear it

Apr 23, 2013 | 04:53 AM

dansflhti

Outstanding HDF Member

Joined: Feb 2007

Posts: 2,837

Likes: 50

From: usa

My 09 does it with the HD Down load,and I think my 06 Standard did it too.

Apr 28, 2013 | 08:45 AM

Gearhead3

Road Captain

Joined: Jan 2009

Posts: 739

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From: St. Louis

Sorry for the delayed response but I haven't been on here in over a month and am finally catching up today. I posed this same question 2 1/2 years ago and learned quite a bit from some of the moe knowledgeable individuals on here.
https://www.hdforums.com/forum/touri...1800-rpms.html
Posts 8,9 and 13 are the ones to focus on. Very enlightening.

Apr 28, 2013 | 10:53 PM

ke5rbd

Thread Starter

Road Warrior

Joined: Apr 2010

Posts: 1,648

Likes: 37

From: Monroe, Louisiana

Quote:

Originally Posted by Gearhead3

I went and read the posts and I still don't think it is fuel related. I am monitoring on Power Vision live and soon as it hits 1800 Rpm's the timing shuts off for about one or two revolutions then turns back on to 25 degrees which is the closed timing table degrees. The fuel doesn't cut off, atleast the PV doesn't show it. This a harley table not just Power Vision. The fuel may shut off at the same time but it is not shut off during deceleration as there is a table called deceleration fuel. It is also a harley table. If you add fuel to the deceleration table you will notice a change in the engine braking. If you take it away it won't brake nearly as hard and it will pop out the exhaust. The guy that said he could tune it out with a SERT probably just leaned the deceleration table out where there was no noticeable engine braking. Probably was popping, but some folks like that. Not that important any way. I use it to know when to get on the brakes as the engine is no longer braking.

Apr 29, 2013 | 06:59 AM

grbrown

Club Member

Joined: Jun 2007

Posts: 45,429

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From: Bedford UK

Way back in the 80s/90s Harley was using a step-change in timing just like that, as one of the ways of keeping noise levels down for the EPA tests. I wonder if they are still doing that? With my carb bike a change of ignition module cured it, by giving a more traditional advance curve. Does your PV have that facility?