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Engine knock at low to mid RPM

 
  #1  
Old 10-06-2013, 08:43 PM
cavmedic
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Default Engine knock at low to mid RPM

I know there is a thousand posts on this as I've been searching for two days on this .


2009 xl1200C

The knocking sound I get is best described as someone tapping real fast on the inside of the primary cover ( kinda hollow sound) with a ball peen hammer . It ONLY happens at a certain engine rpm under load and on decel. If I pull the clutch it immediately stops. If I had to say what RPM , I'd say best guess it was between 2500-3500 RPM and only there for a few hundred plus or minus . .. ( like resonating at a specific rpm)

This isnt the normal noises ( sewing machine ,little bit of tapping , etc ) , as it sounds like it is below the top end and the best reproduction was knuckle taps on the primary case .

It's not a ping , sounds different , run either 92 or 94 ( so the pump says) , but it is definitely a knock . Warm , cold , doesn't matter.

Tonight I adjusted the primary chain and it is still there .

It's just between that one RPM .

Bike has a little over 12K .

I did see a youtube video of a guy who had a loose nut on the front gear
( compensator?) and when he wiggled the gear , it kind of had that same noise , but with cameras and computers , the sound could have been altered a bit .

I have not tried it with front brake applied and slowly putting load in it yet and having someone listen with a scope or screwdriver YET.

I have the bike going back in on Tuesday for Rocker Seal replacements as it has a slight oil seep , but before I have them on a wild goose chase for something that MAY be normal, wanted to see if I am kind of on the right path here . Especially that I have warranty ..


I've only had the bike for two weeks , first Harley , so now that im getting more comfortable with the bike , Im able to pick out some different things that I may not have heard when I first picked it up ...
 
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Old 10-07-2013, 01:03 AM
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If it were my bike, I'd be pulling off the primary cover and checking that nut.
 
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Old 10-07-2013, 06:27 AM
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I think I may do that today. Even though it is going into the shop tomorrow for those seals , just for personal satisfaction.
 
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Old 10-07-2013, 06:43 AM
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Just to let you know....Sportsters do NOT have a compensator nut. Only the big twins do........
 
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Old 10-07-2013, 06:47 AM
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Originally Posted by xFreebirdx View Post
Just to let you know....Sportsters do NOT have a compensator nut. Only the big twins do........

Just a gear nut then ?



This is the best reproduction of the sound ........
 
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Old 10-07-2013, 08:19 AM
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Originally Posted by cavmedic View Post
Just a gear nut then ?


This is the best reproduction of the sound ........

Yes and yours will look more like the picture I've posted. When searching for information for your bike. You need to stay within the years model.

This is a pic showing how to lock the front and rear gears to keep them from spinning when turning with a wrench... I posted it to show you what it looks like under your primary cover.
 
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Old 10-07-2013, 08:49 AM
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Awesome. I started with that search but you know how YouTube searching goes. Before you know it , it's 4 hours later and your sucked into something else.
 
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Old 10-07-2013, 09:31 AM
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I'm just going to have the shop deal with it tomorrow when it goes in for the other stuff. I left my car keys in my wife's car yesterday and she is at work with them today. It's raining and we are under a tornado watch, I really don't feel like going out on either bike in this crap.


< feeling slightly agitated at the moment>
 
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Old 06-11-2018, 11:17 AM
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Resurrecting this old thread. Recently heard what it sounds like OP is describing. Sounds exactly like what OP wrote in the original post " knuckle taps on the primary case". Does not sound like it has anything to do with top end misfire, etc. Anybody else have a sound like this > low rpm under, slight load < ?
 
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Old 06-11-2018, 06:06 PM
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Did you pull the primary cover to check things out?
 

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