GL1000 compression

Information and questions on GL1000 Goldwings (1975-1979)
Post Reply
Posts: 3
Joined: Fri Apr 22, 2016 5:28 pm
Location: New Ulm, Mn.
Motorcycle: 1977 GL1000 2001 FLST 2002 VT750C

GL1000 compression

Post by g&kengines »

I have a 1977 GL1000 that sat a lot. I went through carbs and stuff and it really ran nice, it's gone down hill since. It has very low compression on all cylinders but #2 is down around 25 lbs. Then I did a leak down and all check out 8 to 10 percent leak down, very good! Then thinking bad cylinder walls I started the leak down from bottom dead center and brought the piston up, again only 8% all the way up. Then I put brake clean in the intake valve pocket to see how much was coming by the valve seat, very little which would confirm leak down. Now doing this to all four and turning the motor over and getting a small amount of liquid into each cylinder I do another comp. test. I now have 130 lbs. on 2 cyl. and 115 on the other two. Did I clean the valve guides or help seal the rings, thinking the valves may be hanging up slightly to cause the low comp. Now I remove the heads and have a valve job done and all cyl. look good. Reassemble everything and still only have 25lbs comp. on #2 cylinder and leak down again from bottom of cylinder and again only 7 to 8 % leak down. What in the world for a problem do I have??

Old Fogey
Posts: 844
Joined: Fri Oct 30, 2009 2:09 am
Location: Glasgow Scotland
Motorcycle: 1976 GL1000
1979 GL1000

Re: GL1000 compression

Post by Old Fogey »

Sounds like your rings are shot. If you are making a max of 130 on any cylinder, with the rings wetted, rebuilt heads and the throttle fully open you have rings problems. In that scenario you should be up around 150-160 on a well used engine.
Check that the piston is lifting properly on #2 and not sticking as that would not help the reading.
'Impossible' is just a level of difficulty! The only stupid question is the one you didn't ask first!

( Seriously, you haven't read all 115 pages of my website ?? :shock: )
Post Reply