loud knock at low rpm


Information and questions on GL1100 Goldwings (1980-1983)
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81goldwings
Posts: 3
Joined: Fri Aug 21, 2015 10:57 am
Location: calumet, mi
Motorcycle: 1981 GL1100 Aspencade
1981 GL1100 Standard

loud knock at low rpm

Postby 81goldwings » Tue Sep 01, 2015 7:00 am



First time on this site,so plz bear with me. I am trying to resurrect a 81 gl1100. The bike was a basket case and now after about 3 months I'm getting close to being able to get on and ride. The question I have is once I get the bike started at low rpm there is a pretty loud knocking sound coming from engine. I just recently saw a youtube video of a guy with the same issue and he was asking the same question. Valves are all adjusted proper, exhaust is good. Knocking goes away when accelerated, but again returns at low rpm. Can anyone give me an idea of what I'm up against?



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roadwanderer2
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Location: sweetwater, Tennessee
Motorcycle: 83 GL1100A aspencade, previously owned, 1981 honda GL500i silverwing interstate, 1974 yamaha xs400, 1974 Honda cb450 twin cam, 1983 honda vt30, 1982 honda 700 shadow, 1972 cb750four, and my first bike, a brand new 1982 honda CM400e. and a new to me 1986 GL1200 aspencade SEi
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Re: loud knock at low rpm

Postby roadwanderer2 » Tue Sep 01, 2015 7:11 am

a few things come to mind....wrist pin, connecting rod, rod bearing, bad rocker arm or crank shaft perhaps? how many miles are on the bike, it might be time for a engine tear down to find it. better finding it now than have it break apart while your out on the road somewhere and get stuck.

stuart.

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spiralout
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Motorcycle: 1975 GL1000 (gone)
1980 GL1100I (with '77 1000 engine)
1996 GL1500 SE

Re: loud knock at low rpm

Postby spiralout » Tue Sep 01, 2015 7:59 am

Or it could be something as minor as a carb synch.

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dingdong
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Re: loud knock at low rpm

Postby dingdong » Tue Sep 01, 2015 9:07 am

Better description of "knocking" would help or a link to the video. One mans knock is another mans rattle. ;)

Tom
Tom

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Grindl
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Motorcycle: 1978 GL-1000 , 1983 GL-1100A Aspencade

Re: loud knock at low rpm

Postby Grindl » Tue Sep 01, 2015 9:56 am

I just finished pulling the motor out of my "83" A-cade ; and replaced it with another motor from a identical "83" A-cade . What began as a light "tapping" at low RPM ; developed into a full blown "BANGINING" at all ranges . I agree with Roadwanderer regarding riding it . Don't do it till you figure out what's , what . Could be painful , and expensive .
I'll be tearing the bad one apart to find out what the problem is , and if it's "fixable" , I'll do it . If not , I have a whole bunch of excellent "back-up" parts . Heads , Front cover , etc..... :lol:

81goldwings
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Location: calumet, mi
Motorcycle: 1981 GL1100 Aspencade
1981 GL1100 Standard

Re: loud knock at low rpm

Postby 81goldwings » Tue Sep 01, 2015 10:25 am

Thanks all for the replies! To help you with my problem I should have much more detailed and specific. Basket case means bike was wrecked and as a result was parked in backyard under a picnic table for six years. Engine was seized up. Stripped down to frame and started rebuild. Went through engine and much to my surprise everything was good. Replaced rear cover that was cracked and started putting back together from a new frame up. Carburetors were in the roughest shape of all, but rebuilt them and got bike running. Thats when I noticed the knock. Pretty loud at 950-1000 rpm. Once accelerated knock goes away. Idles back and there it is again. Of all the great replies I"m leaning toward the carb situation and was even thinking seriously about 4-1 single conversion. Would greatly appreciate any and all feedback on that thought.
81Goldwings

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roadwanderer2
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Location: sweetwater, Tennessee
Motorcycle: 83 GL1100A aspencade, previously owned, 1981 honda GL500i silverwing interstate, 1974 yamaha xs400, 1974 Honda cb450 twin cam, 1983 honda vt30, 1982 honda 700 shadow, 1972 cb750four, and my first bike, a brand new 1982 honda CM400e. and a new to me 1986 GL1200 aspencade SEi
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Re: loud knock at low rpm

Postby roadwanderer2 » Tue Sep 01, 2015 10:57 am

your right about that dingdong, and spiral, lets hope for his sake its as simple as a carb problem, but, if the noise is that noticeable, i would lean on something internal inside the motor......

81, you said you replaced the rear cover, is it possible that something in the clutch could be banging around inside the clutch cover? and unless your building your own 4 into 1 carb set up, the price will be quite less than going out and buying one that's already been made up. the prices for ones that are already made can run into hundreds of dollars. ive seen them on eBay going for upwards in the 300- to well over 700 dollar range.

stuart.

81goldwings
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Motorcycle: 1981 GL1100 Aspencade
1981 GL1100 Standard

Re: loud knock at low rpm

Postby 81goldwings » Tue Sep 01, 2015 12:14 pm

thanks again all for replies, got to go to work. Probably going to have to do some dismantling, but thats OK. Got to much into this adventure now to not go a little further with investigation.

81Goldwings

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roadwanderer2
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Motorcycle: 83 GL1100A aspencade, previously owned, 1981 honda GL500i silverwing interstate, 1974 yamaha xs400, 1974 Honda cb450 twin cam, 1983 honda vt30, 1982 honda 700 shadow, 1972 cb750four, and my first bike, a brand new 1982 honda CM400e. and a new to me 1986 GL1200 aspencade SEi
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Re: loud knock at low rpm

Postby roadwanderer2 » Tue Sep 01, 2015 1:27 pm

good luck with it and let us know what you find.

stuart.

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702scottc
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Re: loud knock at low rpm

Postby 702scottc » Tue Sep 01, 2015 9:49 pm

Verify that the the timing belts are installed correctly, if the engine is out of time it will knock yo best the band.

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Fatwing Chris
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Re: loud knock at low rpm

Postby Fatwing Chris » Thu Sep 03, 2015 6:06 pm

spiralout wrote:Or it could be something as minor as a carb synch.


Totally agree!If it's not hitting on all 4 at an idle it could knock like something wants to get out.If it was a rod knock(either end) or a scuffed piston it would get worse with higher rpm's not better.The drive chain at the back of the motor can make some wild noises also when it's not running right.
If I'da known it would last this long,I'da taken better care of it.
Chris
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Darkside # 1602

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roadwanderer2
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Joined: Thu Aug 08, 2013 4:03 am
Location: sweetwater, Tennessee
Motorcycle: 83 GL1100A aspencade, previously owned, 1981 honda GL500i silverwing interstate, 1974 yamaha xs400, 1974 Honda cb450 twin cam, 1983 honda vt30, 1982 honda 700 shadow, 1972 cb750four, and my first bike, a brand new 1982 honda CM400e. and a new to me 1986 GL1200 aspencade SEi
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Re: loud knock at low rpm

Postby roadwanderer2 » Thu Sep 03, 2015 6:14 pm

not trying to highjack this thread, but let me ask you guys this......if one spark plug was way out of gap, could that cause a knock at an idle and seem to go away at higher rpm's?..........just curious.

stuart.

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spiralout
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Re: loud knock at low rpm

Postby spiralout » Thu Sep 03, 2015 7:34 pm

Something I've noticed about new 4 cyl wing owners that are coming from other types of bikes (OP says he has two, though) is that they usually think that the marbles rolling around inside sound primary chain slap an out of tune motor is a knock and something seriously wrong. Most of the time it's nothing that setting valve clearances, timing and synching doesn't take care of. Even then, a perfectly tuned flat 4 isn't going to idle as smoothly as what they were used to before.

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roadwanderer2
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Joined: Thu Aug 08, 2013 4:03 am
Location: sweetwater, Tennessee
Motorcycle: 83 GL1100A aspencade, previously owned, 1981 honda GL500i silverwing interstate, 1974 yamaha xs400, 1974 Honda cb450 twin cam, 1983 honda vt30, 1982 honda 700 shadow, 1972 cb750four, and my first bike, a brand new 1982 honda CM400e. and a new to me 1986 GL1200 aspencade SEi
Contact:

Re: loud knock at low rpm

Postby roadwanderer2 » Thu Sep 03, 2015 7:39 pm

that's a possibility also. i know from my own personal experience that my 2 cylinder GL500i silverwing interstate sounded way different than this 4 cylinder GL1100 aspencade.

stuart.

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mytown
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Re: loud knock at low rpm

Postby mytown » Sun Sep 06, 2015 5:15 am

I had a noise that may be similar to yours. It turned out that the idle jet was plugged on the number 1 cylinder and that the noise was primary chain slap when the engine hesitated. It also seemed to go away at higher rpms, perhaps because that jet is not in play at higher rpms. Here's a before and after-cleaning video in which the noise I am referring to can be heard.


P.S. The opening for that jet is very small.

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RBGERSON
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Re: loud knock at low rpm

Postby RBGERSON » Sun Sep 06, 2015 8:20 am

95% it's out of synch do a carb synch; easy to do if you have the gauges or you can make a tube version for under $10..
HAD LOTS OF GOLDWING 75-83
NOW INTO 1500'S..RIDING A 1998 SE

FAIR WINDS,
RB

mike82state
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Re: loud knock at low rpm

Postby mike82state » Mon Sep 07, 2015 11:19 pm

i agree with the carb synch . just did mine that soundd like yours and now she runs smooth and idols awsome and no more knock on idol. get yourself a gauge set or carb tune is you best investment, or you can make yer own. my bike is a totally diffrrent bike now :D
Stress relief comes on 2 wheels
I suffer from P.M.S....... Parked motorcycle syndrome,

f1xrupr
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Motorcycle: 1980 gl 1100 Std. Vetter

Re: loud knock at low rpm

Postby f1xrupr » Fri Sep 11, 2015 4:28 pm

Carb sync....maybe idle it up a little. Aside from chain slap, the alternator is gear driven, and the hub that turns is heavy! If the engine don't idle smooth, the gear chatter can be noticeable. Also, might try disengaging the clutch while idling-se if that makes it quieter.
You might try a oil pressure gauge, or, get the engine running temperature, shut it down, then with the engine switch off, see if you can make the oil light go out just using the starter (might take several seconds). If you can, your bearings are at least "pretty good". (Again-engine must be hot).


My exercise bike is a goldwing.


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