Rear Cylinder Noise - EVO
Thread Starter
|
Road Warrior
Joined: Dec 2015
Posts: 1,416
Likes: 317
From: CA
Rear Cylinder Noise - EVO
I have this annoying noise which I've isolated to the rear cylinder. Both front and rear spark plugs are a nice tan. The primary belt is adjusted so it's not that.
It seems like a breathing sound rather than a grinding or ticking sound.
I've attached a .wav file so you can hear. The sound is exaggerated in the recording. The motor overall sounds ok other than this sound which has appeared over a few hundred miles of driving.
In the attached file, in the moments when you don't hear that predominant chugging sound, it's when I move the mic away from the rear cylinder. This sound is louder on the side opposite the carb.
Any ideas on this? Thanks for any help.
It seems like a breathing sound rather than a grinding or ticking sound.
I've attached a .wav file so you can hear. The sound is exaggerated in the recording. The motor overall sounds ok other than this sound which has appeared over a few hundred miles of driving.
In the attached file, in the moments when you don't hear that predominant chugging sound, it's when I move the mic away from the rear cylinder. This sound is louder on the side opposite the carb.
Any ideas on this? Thanks for any help.
Thread Starter
|
Road Warrior
Joined: Dec 2015
Posts: 1,416
Likes: 317
From: CA
Compression 140 rear, 130 front. So the rear is actually better.
I will check for exhaust leak. It runs just fine. I've been going through a saga of a leaky carb which turned out to be a hairline crack in the fuel inlet which is now fixed. I'd think that if it were an exhause leak it would be louder on the exhaust side of the engine but I'll check it out.
I will check for exhaust leak. It runs just fine. I've been going through a saga of a leaky carb which turned out to be a hairline crack in the fuel inlet which is now fixed. I'd think that if it were an exhause leak it would be louder on the exhaust side of the engine but I'll check it out.
Elite HDF Member
Joined: Nov 2006
Posts: 3,909
Likes: 6
From: Livingston, Texas
You can go to Harbor freight and get a Stethoscope that might help.
http://www.harborfreight.com/mechani...ope-69913.html
http://www.harborfreight.com/mechani...ope-69913.html
Thread Starter
|
Road Warrior
Joined: Dec 2015
Posts: 1,416
Likes: 317
From: CA
There's been so much going on with this bike it may have been there all along and I just didn't notice but it seems to have arisen during the past couple days (including a 200 mile ride).
I've been using a steth for more years than I want to admit - a stethoscope check reveals the same noise in both valve covers - ie, nothing unusual. The only thing I can say is that it's from the rear cylinder, and more prominent on the driver side. Interestingly I can hear the sound without the steth but I don't hear that sound amplified in any part that I've tried to listen to.
I did an exhaust leak check with a rather smokey incense stick and no leaks discernible. I also checked around the valve covers to be sure.
One thing is odd - I check the plug wires and I don't get any reading other than infinity for resistance. They do look pretty bad and they have this Kuryakin lighting device on them. Unfortunately I don't have a good wire to check. Long shot but maybe a weak spark? The plugs look aces!
I'd be very happy if this was the normal Harley cacophony but I'm all ears for any ideas.
I've been using a steth for more years than I want to admit - a stethoscope check reveals the same noise in both valve covers - ie, nothing unusual. The only thing I can say is that it's from the rear cylinder, and more prominent on the driver side. Interestingly I can hear the sound without the steth but I don't hear that sound amplified in any part that I've tried to listen to.
I did an exhaust leak check with a rather smokey incense stick and no leaks discernible. I also checked around the valve covers to be sure.
One thing is odd - I check the plug wires and I don't get any reading other than infinity for resistance. They do look pretty bad and they have this Kuryakin lighting device on them. Unfortunately I don't have a good wire to check. Long shot but maybe a weak spark? The plugs look aces!
I'd be very happy if this was the normal Harley cacophony but I'm all ears for any ideas.
Club Member
Joined: Aug 2008
Posts: 22,861
Likes: 17,917
From: Lafayette, Louisiana
Although not the problem, that compression seems kind of low.
How is the breather system setup? What year is it?
I don't think it is your spark plug wires although a new set is rather cheap.
How is the breather system setup? What year is it?
I don't think it is your spark plug wires although a new set is rather cheap.
Trending Topics
Thread Starter
|
Road Warrior
Joined: Dec 2015
Posts: 1,416
Likes: 317
From: CA
1995. That was a quick and dirty compression test but I forgot to open the throttle. That was with the engine warm but not hot. Air filter on.
Breather setup - has a K&N air filter with the horseshoe breather tube on the head breather ports that descends in a hose to the base of the bike.
Breather setup - has a K&N air filter with the horseshoe breather tube on the head breather ports that descends in a hose to the base of the bike.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Advanced
Joined: Jan 2012
Posts: 98
Likes: 4
From: Latvia E.U.
I was worried about identical noise of my 1996 ultra. But I noticed that sound after replacing an air cleaner to K&N. After all tests everything is o.k., only that chugging noize which is a simple intake breath of motor. Keep calm, engine is o.k.
My thread: https://www.hdforums.com/forum/evo-c...it-normal.html
My thread: https://www.hdforums.com/forum/evo-c...it-normal.html
