Compression rate, Lb/po2


Information and questions on GL1000 Goldwings (1975-1979)
  • Sponsored Links
User avatar
jarvait
Posts: 14
Joined: Sat Apr 24, 2010 3:07 pm
Location: Roberval, Québec, Canada
Motorcycle: 1978 GL1000

Compression rate, Lb/po2

Postby jarvait » Mon May 03, 2010 7:20 am



Hi,

Also, i will make a compression test on my 1000 GL, 1976. What is the normal compression test for this bike. I have 42000 miles.

Thanks,

Roger



User avatar
WingAdmin
Site Admin
Posts: 17046
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: Compression rate, Lb/po2

Postby WingAdmin » Mon May 03, 2010 9:26 am

According to the GL1000 service manual:

Normal compression pressure is 171 psi. Compression above 199 psi indicates that carbon deposits have accumulated in the combustion chamber or on the piston.

Compression below 142 psi, or a variation of more than 15 psi between cylinders, indicates leakage at the valves, piston rings or cylinder head gasket.

User avatar
RBGERSON
Posts: 2621
Joined: Tue Mar 09, 2010 7:57 am
Location: SCOTTSDALE, AZ
Motorcycle: 98 SE GL 1500
had every year from 75 to 83

Re: Compression rate, Lb/po2

Postby RBGERSON » Mon May 03, 2010 1:15 pm

165 to 170 excellent
160 to 165 great
155 to 160 very good
150 to 155 good
140 to 145 good
140 to 145 at lower limits of specs
130 to 140 she runs but needs work
130 and lower fix her..she will run but not well.
HAD LOTS OF GOLDWING 75-83
NOW INTO 1500'S..RIDING A 1998 SE

FAIR WINDS,
RB

User avatar
jarvait
Posts: 14
Joined: Sat Apr 24, 2010 3:07 pm
Location: Roberval, Québec, Canada
Motorcycle: 1978 GL1000

Re: Compression rate, Lb/po2

Postby jarvait » Tue May 04, 2010 12:45 pm

I made my test.

Number 1: 140
Number 2: 140
Number 3: 142
Number 4: 130

Also, i dont have electricity on spark plug number 3 and number 4. I suspect the left coil.

Roger

User avatar
jarvait
Posts: 14
Joined: Sat Apr 24, 2010 3:07 pm
Location: Roberval, Québec, Canada
Motorcycle: 1978 GL1000

Re: Compression rate, Lb/po2

Postby jarvait » Tue May 04, 2010 2:31 pm

How to check if the coil is good ?
Also, where i can get a brand new one if mine is defect ?

Roger

User avatar
thrasherg
Posts: 1837
Joined: Tue Oct 20, 2009 11:21 am
Location: Plano, TX
Motorcycle: 2004 GL1800, 2005 Honda Shadow 750, 2008 Yamaha R6 with RG500 engine, CRF450X, CRF230, CRF250X, XR200, CR500

Re: Compression rate, Lb/po2

Postby thrasherg » Tue May 04, 2010 3:56 pm

Roger,

all your values seem a little low. You did make the meausrements correctly? You need to hold the throttle wide open whilst you crank the engine over on the starter, you keep cranking until the gauge stops climbing. If you don't crank the engine long enough or don't hold the thrott;e wide open you can get low readings. Just want to check you did it correctly before you pull the engine apart for low compression and find it was fine.. If the readings are correct, you can try putting a few drops of oil in the bores and then take the measurements again, if they increase significantly it usually indicates you have worn rings or glazed bores. If the oil doesan't change the compression reading then it's usually valves that are burnt or not seating correctly. This test just gives you an idea of which parts to check when you take the engine apart.

Gary

User avatar
jarvait
Posts: 14
Joined: Sat Apr 24, 2010 3:07 pm
Location: Roberval, Québec, Canada
Motorcycle: 1978 GL1000

Re: Compression rate, Lb/po2

Postby jarvait » Tue May 04, 2010 5:39 pm

Ok Gary,

I will do my test again tomorow.

Thanks.
Roger

User avatar
jarvait
Posts: 14
Joined: Sat Apr 24, 2010 3:07 pm
Location: Roberval, Québec, Canada
Motorcycle: 1978 GL1000

Re: Compression rate, Lb/po2

Postby jarvait » Wed May 05, 2010 4:00 pm

I did my test again,

Piston 1: 162
Piston 2: 160
Piston 3: 160
Piston 4: 155

I put 10 ml of oil into each chamber. I did an other test.

Piston 1: 190
Piston 2: 190
Piston 3: 195
Piston 4: 190

User avatar
Victour78
Posts: 14
Joined: Sat May 01, 2010 1:08 pm
Location: Lakeland , Florida
Motorcycle: 1978 1000 GoldWing Naked
Contact:

Re: Compression rate, Lb/po2

Postby Victour78 » Thu May 06, 2010 12:01 am

Sounds great after a few miles maybe the valves will seat better.. But they are Still very good...

User avatar
jarvait
Posts: 14
Joined: Sat Apr 24, 2010 3:07 pm
Location: Roberval, Québec, Canada
Motorcycle: 1978 GL1000

Re: Compression rate, Lb/po2

Postby jarvait » Thu May 06, 2010 6:02 am

Do you think, i have to fix the rings and the valves ? Also, i dont have current on sparkplug 4 and 2. I suspect the coil.

Thanks

Roger

User avatar
thrasherg
Posts: 1837
Joined: Tue Oct 20, 2009 11:21 am
Location: Plano, TX
Motorcycle: 2004 GL1800, 2005 Honda Shadow 750, 2008 Yamaha R6 with RG500 engine, CRF450X, CRF230, CRF250X, XR200, CR500

Re: Compression rate, Lb/po2

Postby thrasherg » Thu May 06, 2010 4:16 pm

Nothing wrong with that engine. I would leave well alone, I suspect after a few miles the compression will come up.. You might want to try adding a engine cleaner to the fuel to remove any carbon that might have built up on the valves. In the UK it's called REDEX, but I am sure you have something similar over here.. Just pour it into you gas tank and as you ride it cleans the valves and combustion chamber.

User avatar
jarvait
Posts: 14
Joined: Sat Apr 24, 2010 3:07 pm
Location: Roberval, Québec, Canada
Motorcycle: 1978 GL1000

Re: Compression rate, Lb/po2

Postby jarvait » Thu May 06, 2010 5:25 pm

Thank you so much,

I will try it.

Roger

User avatar
Victour78
Posts: 14
Joined: Sat May 01, 2010 1:08 pm
Location: Lakeland , Florida
Motorcycle: 1978 1000 GoldWing Naked
Contact:

Re: Compression rate, Lb/po2

Postby Victour78 » Thu May 06, 2010 10:31 pm

Seafoam buy a 1/2 qt. bottle ... In the US.. it is some great stuff.. but it won't fix the coils.. Now remember that you must Ground the other plug to get fire on the other..Because both plugs fire at the same Time..1&4 and 2&3.. My 1&4 are not firing like they are supposed to either.. I have pulled out all my Hair nothing helps..Try misting some gasoline in the Air box.. don't over do it and see if
it runs on all four then.. I used a hose on a bottle that way I could hit the intake that seemed to not be running..

User avatar
jarvait
Posts: 14
Joined: Sat Apr 24, 2010 3:07 pm
Location: Roberval, Québec, Canada
Motorcycle: 1978 GL1000

Re: Compression rate, Lb/po2

Postby jarvait » Fri May 07, 2010 6:26 am

I checked the left coil and it is over. Where i can buy a new one ? It is not available at Honda.

Thank

Roger

terryjenner
Posts: 7
Joined: Fri Aug 21, 2009 9:25 pm
Location: great falls, mt
Motorcycle: 1975 gl1000

Re: Compression rate, Lb/po2

Postby terryjenner » Tue May 18, 2010 2:54 pm

here is good article on finding out the source of low compression:
(cut and paste to your address bar)


http://www.ngwclub.com/forum/viewtopic. ... 7a5bfc763b




Return to “GL1000 Information & Questions”




Who is online

Users browsing this forum: Bing [Bot] and 2 guests