Knocking noise from engine

Information and questions on GL1000 Goldwings (1975-1979)
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Joined: Mon Sep 14, 2020 6:10 pm
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Motorcycle: 1975 Gl1000

Knocking noise from engine

Post by gl1000197555 »

Hey everyone,

Restoring a 75 GL1000 - the bike was starting but wasn't idling well. Pulled the carbs off and gave them a cleaning, then put them back on. Immediately once trying to start the bike, this 'knocking' sound started. No adjustments were made besides those to the carb.

Does anyone have any idea what could be causing it?

P.S. I know the spark plug wires are off - the noise was happening with and without.

Video with audio can be found at

Thanks, everyone!

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Joined: Sun Sep 29, 2013 2:33 pm
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Motorcycle: 1977 GL1000

Re: Knocking noise from engine

Post by ohiobobcat »

I don't know for sure what it is, but it sounds kinda like what I would expect from a slide in one of the carbs bouncing up and down. Did you find an extra spring after you were finished? Does it make the same sound if you turn it over manually?
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Motorcycle: 1975 GL1000K1
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Re: Knocking noise from engine

Post by Maz »

I can't play your video but, from experience, knocking from these engines is horrendous if not all cylinders are firing. If you've played with carbs, it's probably fuel related. Check for spark on all 4 first (and make sure the plug wires are connected to the correct spark plugs) then check that fuel is definitely reaching each cylinder.
Ironically, Common Sense is the LEAST common of all senses!
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Motorcycle: 1975 GL1000, 1976 GL1000, 2013 BMW R1200RT, two restored 1971 K1 CB750s, 2019 Triumph Speed Twin

Re: Knocking noise from engine

Post by cfairweather »

I agree with Maz. I think you have two spark plug wires reversed. Does it backfire when trying to start it? What you are hearing is the carb slides.

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