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Discussion Starter #1
I bought a 75 gl 1000 and want to build a cafe racer. The compression test was very low, 40-50 on each cylinder. Can I get by with honing the cylinders and NOS rings along with a valve guide replacement and seat grinding, or should I go ahead with cylinder boring with oversize rings?
 

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I bought a 75 gl 1000 and want to build a cafe racer. The compression test was very low, 40-50 on each cylinder. Can I get by with honing the cylinders and NOS rings along with a valve guide replacement and seat grinding, or should I go ahead with cylinder boring with oversize rings?
Depends on your expectations.
 

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If it’s been setting for sometime, pour some marvel mystery oil in the cylinders and lit it set for a few days,could be the rings are kinda stuck and that will help but you might just run it for a while and see if the compression,did you drop some oil in the cylinders before you did the check,Goldwing aren’t noted for wearing out the rings .rings might not be available.
 

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If it’s been setting for sometime, pour some marvel mystery oil in the cylinders and lit it set for a few days,could be the rings are kinda stuck and that will help but you might just run it for a while and see if the compression,did you drop some oil in the cylinders before you did the check,Goldwing aren’t noted for wearing out the rings .rings might not be available.
Jim,
If an engine sits that long you can get low compression under normal conditions. Brand new engines will have low compression until they are run. Compression tests should be run on warm engines, spark plugs removed and throttle wide open. Otherwise they don't necessarily mean much. It is very odd they are all low. I susspect an improper compression test. Might be just fine.:cool:
 

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Jim,
If an engine sits that long you can get low compression under normal conditions. Brand new engines will have low compression until they are run. Compression tests should be run on warm engines, spark plugs removed and throttle wide open. Otherwise they don't necessarily mean much. It is very odd they are all low. I susspect an improper compression test. Might be just fine.:cool:
knowing that these motors don’t wear out the rings for a loooong time ,I suspect it’s fine,

he hasent said if it runs or how many miles on it so maybe he will come back soon

you staying warn up north,rode the 1500 100 miles 2 days ago but it’s nasty here now.
 

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Discussion Starter #6
That's good advice. A cycle shop did the trickle down test. The bike is low mileage, 27,000 but was sitting a long time, outside under a tarp, not ideal conditions for anything mechanical. I think I'll do as suggested and get it running, then do a compression test myself.
 

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Perfect,carbs are easy on these,points might give you a hard time But don’t run it till you get the timing belts changed ,if they break it will bend valves
 

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That's good advice. A cycle shop did the trickle down test. The bike is low mileage, 27,000 but was sitting a long time, outside under a tarp, not ideal conditions for anything mechanical. I think I'll do as suggested and get it running, then do a compression test myself.
The fuel system is probably so varnished it will not run as is. I would take the air cleaner off and put some gas in a spritzer bottle. You should be able to keep spritzing gas in the air cleaner box for a few minutes of running. Just keep spritzing the gas as needed to keep her going. After a few minutes of running I bet the compression comes right back up.

Hopefully the piston and cylinder has not corroded together where it won't turn over. If the shop did the leakdown test they did not need to spin the engine like a compression test. I bet you have 50% leakage and not 50 PSI compression. Leakdown tests are measured in percentage. Good luck.
 

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You could get an inexpensive borescope to have a look at the cylinders through the spark plug holes. Here's a pic of my number one cylinder with a borescope:
Number 1 - 1.JPG

The borescope I used is:
Borescope 1.jpg
 
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