78 GL1000 Compression


Information and questions on GL1000 Goldwings (1975-1979)
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Kbkc2002
Posts: 14
Joined: Fri Apr 17, 2020 8:33 am
Location: Tremonton, Utah
Motorcycle: 1978 Honda Goldwing GL1000

78 GL1000 Compression

Post by Kbkc2002 »



Engine is off bike with mufflers and carburetor assemb!y off.
Compression tested
100
125
130
140
Is that low??
Where do I go from here if it is?
Any help or advice is appreciated
Thanks


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winguyjo
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Re: 78 GL1000 Compression

Post by winguyjo »

a wide range like that is definitely not desireable.
what is the story with this engine ? if it has been sitting unused for years, it is quite common to see poor compression numbers like that, but it is equally as common to see the values improve dramatically with very little run time. the rings tend to stick and produce bad compression numbers.

i would get some sort of penetrating oil into the cylinders and let it sit overnight, then spin by hand to spread it around a bit, let it sit overnight again, then take another compression reading. a leak-down test somewhere along the line will be helpful too.
Kbkc2002
Posts: 14
Joined: Fri Apr 17, 2020 8:33 am
Location: Tremonton, Utah
Motorcycle: 1978 Honda Goldwing GL1000

Re: 78 GL1000 Compression

Post by Kbkc2002 »

The engine has been sitting for about 12 to 15 years.
Thanks for the advice
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Joneszy
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Re: 78 GL1000 Compression

Post by Joneszy »

Kbkc2002 wrote: Wed May 06, 2020 3:43 pm The engine has been sitting for about 12 to 15 years.
Thanks for the advice
Then I wouldn't sweat the compression numbers. My 78 was seized for all intents and purposes after sitting 18 years in a shed. One cylinder showed very low compression as yours did. After the initial firing and half hour run time the weak cylinder was right in range with the other 3. Give it some run time then retest and see what the numbers say after that. Make sure you are checking compression with the throttle wide open and choke off, engine cool not hot.
Kbkc2002
Posts: 14
Joined: Fri Apr 17, 2020 8:33 am
Location: Tremonton, Utah
Motorcycle: 1978 Honda Goldwing GL1000

Re: 78 GL1000 Compression

Post by Kbkc2002 »

Thank you.
That gives me some hope


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