Engine rattle


Information and questions on GL1100 Goldwings (1980-1983)
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jeffbell
Posts: 5
Joined: Thu Jun 21, 2012 3:53 pm
Location: Billings, Montana
Motorcycle: 1983 GL1100A Aspencade

Engine rattle

Postby jeffbell » Tue Jun 26, 2012 10:42 am



I am new member to this forum. But I have been reading it for the past few weeks. Sounds like this is a group of great people all trying to help each other. I was wondering if anyone might be able to help me with a question I have on a bike i just bought. I have a 1983 GL 1100 aspencade with 40500 miles. It has a rattle or buzz sound coming from in the back of the engine. I am wonder if it a normal sound or something I should fix. I have replaced the plugs, oil and filter, and flushed the radiator, flushed and bled the brakes, drained and replaced the rear end oil. Not sure of the maintenance history so my next plan is to check the carb balance , replace the timing belts and adjust the valves. The Bike starts fine, The sound is not there at idle or when the engine is cold. The rattle sound starts to come on after the engine is warm and the engine is at about 3000 rpm. The rattle sound goes away at about 4000 rpm. The sound is not there at idle to about 3000 rpm whether the engine is warm or cold. I have a stethoscope i have used to track done where the sound is located in the engine. I have tracked it down to the back of the engine under the seat area of the engine. I have removed the seat, bags, false tank looking for something that is loose. The sound is like a rattle or a buzz, like a loose piece of sheet metal that a hold down screw has backed out of. My understand is if the crabs are out of sink it will cause a rattle, but only at idle. Any ideas?



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WingAdmin
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Posts: 17050
Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (wife's!)
1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer

Re: Engine rattle

Postby WingAdmin » Tue Jun 26, 2012 11:10 am

If the carbs are out of sync, you will get a rattle at low RPM under high load - think going up a hill in too high a gear, usually below 2500 RPM or so. That is the sound of the primary chain rattling from uneven power pulses. Syncing the carbs will go a long way to resolving that noise. The primary chain is near the back, bottom of the engine. If the engine is not under load (i.e. in neutral) and you are still hearing the rattle, then it is not the primary chain.

It sounds to me from your description like you do in fact have something loose that is resonating at certain engine RPMs. That can be one of the most frustrating noises to track down! You're already heading the right way, using a mechanic's stethoscope to isolate the source.

jeffbell
Posts: 5
Joined: Thu Jun 21, 2012 3:53 pm
Location: Billings, Montana
Motorcycle: 1983 GL1100A Aspencade

Re: Engine rattle

Postby jeffbell » Tue Jun 26, 2012 7:22 pm

Thanks for the incite. The rattle/ buzz will happen even in neutral. other then being a bit annoying. is it something to worry about?

User avatar
WingAdmin
Site Admin
Posts: 17050
Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (wife's!)
1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer

Re: Engine rattle

Postby WingAdmin » Tue Jun 26, 2012 9:18 pm

It depends on what is causing it!

My wife's bike had a piece of heat shield on one of the exhaust pipes that had broken free. The rattle it made at certain engine RPMs was driving her absolutely crazy. Was it hurting anything? Certainly not, but she definitely wanted it fixed, so I did a quick weld and fastened it back in place.

If it's a broken frame weld or motor mount that's causing the rattle, you probably want to know about it (and fix it!). But you won't know unless you find the source of the noise, then decide if it's worth the trouble to you to fix it. :)




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