engine compression


Information and questions on GL1200 Goldwings (1984-1987)
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LDodge
Posts: 54
Joined: Sun Jan 13, 2013 8:29 pm
Location: Smithville, Tn
Motorcycle: 1985 1200 Aspencade (sold)
1995 1500 SE

engine compression

Postby LDodge » Thu Apr 02, 2015 7:41 pm



Hi all --
Does anyone know what the compression (in psi) should be for a '85 1200? A friend tested my four and said one was 70, one was 90 and the other two were 100 (yeah I know it sounds like a rebuild is in my future). Any thoughts on how to improve the compression without rebuilding it?
thanks
Lawrence


Meditation doesn't mean you are sitting still. Enjoy the open road and let the good LORD speak to you (even at 65+mph) ;)

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gre_lauren
Posts: 7
Joined: Sun Jun 24, 2012 7:34 pm
Location: Gig Harbor, Washington
Motorcycle: 1984 VT700c Shadow
1987 GL1200I

Re: engine compression

Postby gre_lauren » Fri Apr 03, 2015 12:39 am

Factory compression for a new motor was 175psi.

as long as your engine runs well and makes good power you should just ride the thing and save $$.

A long time ago there was sold a kit to improve compression in a worn engine. It contained a oil thickener and some pasty grey balls that were dropped through the sparkplug holes.
The mechanism of operation was that when the engine was ran the balls melted onto the piston crown. the oil thickener did just that; thicken the oil to help prevent blow-by.
the melted balls decreased the available space in the combustion chamber thus increasing the compression ratio.

It was a stopgap to a worn engine...the only real way to fix the motor was a teardown and rebuild.

George

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Fatwing Chris
Posts: 741
Joined: Thu Oct 21, 2010 6:10 pm
Location: Ont.,Canada
Motorcycle: 2004 ABS Model Goldwing

Re: engine compression

Postby Fatwing Chris » Fri Apr 03, 2015 7:57 am

I'd try a different guage first of all.These motors would have to be abused really,really badly to be that worn out.There's lots out there with over 200 k on them and still running good.It's more likely that you have stuck rings or valves hanging up.Has it been sitting for a long time?If a different guage doesn't give you better results then I would run some Combustion Chamber Cleaner through it and then recheck.

BTW Were these readings on a warm engine with the throttle wide open?
If I'da known it would last this long,I'da taken better care of it.
Chris
Double Dark
Darkside # 1602

User avatar
LDodge
Posts: 54
Joined: Sun Jan 13, 2013 8:29 pm
Location: Smithville, Tn
Motorcycle: 1985 1200 Aspencade (sold)
1995 1500 SE

Re: engine compression

Postby LDodge » Fri Apr 03, 2015 8:19 am

Thank you George and Chris. My wing has 96+K on it and was sitting the entire (lonnnng) Wisconsin winter. As for when my friend checked the compression I am not sure; though he has been working on bikes for 40+ years so I think it is safe to assume he is using good tools and procedures. I will definitely be putting some engine cleaner in her to see if that help; I was thinking SeaFoam -- any suggestions? Also does anyone have any thoughts on Lucas Engine Treatment?

Hopefully I can get her back on the road; a new bike is just not in the budget right now and our riding season is too short to waste it in a mechanic's garage :D
lawrence
Meditation doesn't mean you are sitting still. Enjoy the open road and let the good LORD speak to you (even at 65+mph) ;)

User avatar
gre_lauren
Posts: 7
Joined: Sun Jun 24, 2012 7:34 pm
Location: Gig Harbor, Washington
Motorcycle: 1984 VT700c Shadow
1987 GL1200I

Re: engine compression

Postby gre_lauren » Sat Apr 04, 2015 2:35 pm

Seafoam is the way to go. Change the engine oil to a high quality 10w40 MC oil. Add some seafoam to the fuel and oil and then run the engine. I believe that you may have stuck rings. The seafoam is an excellent solvent for freeing up those rings. Then as the saying goes;'ride it like you stole it'. That should excercise those rings to reseal and free up all that gunk that built up.

My bike sat for 7 years in a garage before I got it. I did the seafoam thing to it and now it runs great. However the wet climate of washington caused some rust to form on the valves and seats and i have some valve leakage that is evident when it is running. Sounds like tappet noise but from the exhaust pipes. Eventually i will pull the heads and fix that too.

User avatar
LDodge
Posts: 54
Joined: Sun Jan 13, 2013 8:29 pm
Location: Smithville, Tn
Motorcycle: 1985 1200 Aspencade (sold)
1995 1500 SE

Re: engine compression

Postby LDodge » Sat Apr 04, 2015 2:39 pm

Thanks for the advise, though if I stole it I would be very cautious and slow so as not to raise suspicion hehehe. I understand what you are saying though, as soon as I get her back from the garage I will work on getting those rings cleaned up and have fun riding her like I stole here (only I have the pink slip when I get pulled over hehehe, and hopefully (let's all cross our fingers here) she will get a few more thousand miles 8-)


Meditation doesn't mean you are sitting still. Enjoy the open road and let the good LORD speak to you (even at 65+mph) ;)


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