Help identify engine noise
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Road Warrior
Joined: Jul 2011
Posts: 1,326
Likes: 331
From: Central TX
Help identify engine noise
I hope this works, but attached is a video clip of my bike idling. I cant hear it as well in video, as I can in person, but the sound is not a metal on metal sound, but more of a gulping or warble type sound. I know, not the best description, but not sure how else to describe it. If you listen closely, you can hear it a little better around the :26, :34, and :40 second marks on the video. I am aware of the smoke coming from exhaust - never an issue normally, but I checked compression and added a little oil to top of cylinders and did a wet compression test after. The smoke was oil burning off after starting bike. I am not sure what piston slap sounds like. I do have forged pistons and understand they may slap more when cold. 95 cylinders and pistons have been in bike for 17k miles and never heard this noise until a couple months back, after swapping out a Lowcat exhaust for a used FatCat. At first, I thought it might be related to the exhaust, but I had a different FatCat on bike before the Lowcat and never had this sound. Possible issue with heads/valve?
Last edited by txphatboy; Jan 12, 2020 at 11:46 AM.
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Road Warrior
Joined: Jul 2011
Posts: 1,326
Likes: 331
From: Central TX
Sorry guys - cant get video to upload on YouTube. I have heard some car guys say they had gulping sounds come from their intake after installing high flow intake. I only hear this noise at idle, not while riding. I have a higher flow metal mesh filter on bike now. I have a stock size spare K&N - I guess I could install that and see if it makes any difference. IDK - just trying to figure something out. Bike was tuned with current set up, so this does not really make sense.
Sponsor
Joined: Jul 2015
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From: SF Bay area
The sound you describe sounds like intake reversion. Usually described as like tapping on a wooden drum. The more open the AC, the more prominent the sound. Doesn't hurt anything but your ears.
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NO, they DON'T all do that!
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Road Warrior
Joined: Jul 2011
Posts: 1,326
Likes: 331
From: Central TX
Thanks - just wanted to make sure there was not something going on that would cause big problems down the road. Saw quite a few links with same issue, and some sound a lot worse than mine. Appreciate the help
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Road Warrior
Joined: Jul 2011
Posts: 1,326
Likes: 331
From: Central TX
Yeah, that bike sounds a lot worse than mine. The sound on my bike is not constant or near that fast or loud. Maybe I can get my son to load it on his YouTube account, but mine wont work. If a forum member is willing to load it, let me know and I could email or text the video to you.
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