Engine knock
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5th Gear
Joined: May 2019
Posts: 9
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From: nashville
Engine knock
Just rebuilt top end of my 1994 sportster 1200. Runs great but knocking sound from engine. Cyclinders were bored and valves redone at machine shop. Knock is barely noticeable in neutral but when you put in gear and take of it gets worse. Any advice.
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Joined: Oct 2007
Posts: 8,852
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From: Decatur, Alabama
My EVO road king is the same way. Motor was rebuilt, runs fantastic but scares me to death at idle with all of the knocking/banging noises it's making. Runs great at speeds though. Asked my Dad about it and he mentioned it could be the oil. I'm just going to keep on running it.
carl
carl
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Joined: Oct 2015
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From: Pine Flat Dam/South Bay Area, CA
The machinist might have set the piston to cylinder clearances to loose & what you are hearing is piston slap. It's harmless but annoying.
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Joined: Aug 2007
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From: Driftless Area
Years ago, I was coming home from somewhere, and still one state away when I started hearing that one unmistakable sound. My Shovel had 147,000 on that bottom end, and I knew it was time. The thing is, it only knocked when I was leveled off, not on the throttle or off the throttle. So we kind of surged our way home, while I prayed that it stayed together. It never smoked, and still had good power, but the oil pressure went to zero at idle.
Well, we made it. When I split the cases later, there was a .030" deep groove in the crank pin. All the innards are new now, so we're good.
Well, we made it. When I split the cases later, there was a .030" deep groove in the crank pin. All the innards are new now, so we're good.
Cruiser
Joined: Dec 2016
Posts: 195
Likes: 151
From: MA
If it's knocking it's not "running great"
ETA: if it's a heavier knock when you twist the throttle under load it could be bottom end/rod...Piston slap as someone above mentioned usually gets quieter as the engine heats up..can you post up a video with audio of this knock?
ETA: if it's a heavier knock when you twist the throttle under load it could be bottom end/rod...Piston slap as someone above mentioned usually gets quieter as the engine heats up..can you post up a video with audio of this knock?
Last edited by Trench; May 6, 2019 at 05:31 PM.