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MOTOBRICK.COM
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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K.
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The Motobrick Workshop
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Does this engine sound normal to you?
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Topic: Does this engine sound normal to you? (Read 110 times)
3dachshunds
Motobrick Curious
Posts: 30
Does this engine sound normal to you?
«
on:
May 20, 2026, 08:13:42 PM »
I’ve been working on 1992 k100rs since last fall and finally got the bike running (clogged injectors). I was super excited that I finally got it running, but didn’t actually ride until now. (New fluids, new tank innards, new spark plugs). I don’t like how it sounds at idle. It sounds to me either misfire or a problem with crankshaft bearings. It has hesitation at about 4.5-5k RPM, around 80MPH. It starts feeling sluggish. Please let me know what do you think.
https://drive.google.com/file/d/1Qqn2XgcRyBtIj7QKubrpFsX3cLhWUb_L/view?usp=drivesdk
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USA
1992 BMW K75, 2013 Triumph Tiger 800 roadie
Filmcamera
^ Quintessential Motobricker
Posts: 1480
Re: Does this engine sound normal to you?
«
Reply #1 on:
May 21, 2026, 03:44:30 PM »
That does not sound right to me! That intermittent thunk is not something my 1991 K1000 RS does. I sounds like you might be in three cylinders. If you have a gun type thermometer try measuring the heat of the four exhausts as they come out of the engine. If one is much cooler it might not be firing right.
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San Jose, Costa Rica
1991 K100RS 16v ABS1, 2022 Triumph Tiger 900 Rally Pro
Poserbricker
Laitch
Faster than a speeding pullet
Administrator
^ Quintessential Motobricker
Posts: 11424
Re: Does this engine sound normal to you?
«
Reply #2 on:
May 21, 2026, 10:15:43 PM »
Among several causes, defective fuel injectors and faulty coils or coil connections can cause knocking. Were all the injectors replaced, or were they professionally cleaned?
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Along the Ridley in Vermont.
1995 K75 89,000 miles
3dachshunds
Motobrick Curious
Posts: 30
Re: Does this engine sound normal to you?
«
Reply #3 on:
Today
at 12:01:41 AM »
I cleaned injectors by energizing them directly from battery and spraying brake cleaner simultaneously. Probably damaged one or more during the process. I hope that’s the root cause. New injector set should arrive next week from Euromoto.
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USA
1992 BMW K75, 2013 Triumph Tiger 800 roadie
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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K.
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Does this engine sound normal to you?