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I'm getting about 90psi on all cylinders. I've seen 100 stated as normal on this board.Is that about right for GL1000s?



I remember in the late '70s lower compression being used by the auto industry for some reason I don't remember, but that's probably why the Goldwing will run fine on unleaded REGULAR.



What compression are ya'll getting?
 

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90 psi is pretty low. Do a search on the site as there is lots of info.
 

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First you need to make sure you are doing the procedure the same. All 4 plugs out, Choke closed, throttle wide open. With a fully charged battery and good starter. Factory spec is 171 psi. All of those are critical and if not done will result in poor readings. By the book rebuild spec is 140 ish. The critical spec is the deviation between cylinders. Anything over about 15 lbs difference is cause for concern. If there are issues with the readings first check the timing belts for perfect allignment and the valve adjustments. If they are too tight it will have significant impact on the readings.

If a bike has sat expect the readings to be lower than normal. Typically I take a base line reading when I first get a bike then after a few hours of running time then after a few hundred miles on the road. They may change significantly. I have seen engines that started off in the 90 lb area that go up to 150 + after a couple of hundred miles.
 

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Yea...I did forget to open the throttle. I've searched the forum and found lots about tire preasure, but little about actual measurments found on compression tests.

Like your post, you havn't stated what results you've gotten testing your '77.

No offense intended but when people talk about it without actually stating the results of an actual test, it tells me nothing.
 

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A 78 barn find I did in '07 started with 105,120,95,130. After servicing and running a bit, no miles just tuning and such, the readings went up to 130,130,120,130. Still low by the "specs" but I have no reason not to believe the readings continued to rise with use. I no longer own it, but the guy who does, is loving it.

BTW I had forgot the open throttle part at first and was getting in the 60's. Makes a BIG difference in the readings.
 

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Bike at operating temp, throttle fully open, choke fully off, all plugs out, battery fully charged and charging while testing. Bike is 1980 1100 Dry test
Minimum reading---all cylinders, 165 PSIG: maximum reading all cylinders 170 PSIG, wait 10 minutes try again same numbers differential is less than 5 psig

Wet test all cylinders exert 180 + PSIG, all valves set to spec, timing light is strong all cylinders, and timing at spec.

Leak down indicates good pressure for as long as I am patient.

Spark voltage OK at around 30,000 dwell at least long enough to ignite, exhaust is clean, no condensation no smell of excess fuel and sound is strong with palm at exhaust to feel pulses.

Bike gets 60 MPG on an imperial gallon consistently at 100-110 Km / hr 60-65 mph. No backfire, no popping, starts well from -20 to + 35 C runs cooler than usual. Top speed so far 175 Km/hr. Highway speeds good. All 1 up.

This is my experience from a basket case that was re-assembled 3-4 years ago, I am the 9th owner.
 

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Your last set of readings look okay to me. Don't get too caught up in the actual pressure reading, 170psi would be a factory spec engine with a new starter, battery and wiring. Any wear on your starter or its wiring and a slightly weak or partially charged battery will lower the compression reading considerably. A warmed up engine that's been run often will always show higher compression as well. The difference between cylinders should be less than 5psi and yours is well within that so theodds of serious wear in any one cylinder or a bad valve are very unlikely.
 

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170 TO 165 great
165 to 160 very good
155 to 160 good
150 to 155 still good
145 to 150 ok
140 to 145 getting iffy
135 to 140 time to think about fixing something
130 to 135..fix it
less fix now

of course Goldwings will run at 100 fairly well???

As said about all of the these numbers should be fairly even across the cylinders..if more than 5 off and definitely 10 you need to work on it.

timing, valves and rings..assuming good batter and starter.

If you add a little oil to each cylinder and it comes up rings are the issue, if no change valves but it could be timing or valve settings..
 

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The rebuild spec quoted from honda is 140 for the GL1000. I don't see how you can come up with those figures if honda states otherwise.



...mines been runnin' great, but now all of a sudden needs either carbs rebuilt or a coil.
 

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Seems like RB's tabulation is saying the same thing. Iffy means getting to the limit.:baffled:
 

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77GL1 wrote:
Have you tested your '77?
No I haven't.



The bike sat for awhile before I bought it out of a salvage yard. When I first got it running it ran like crap but rings etc. have loosened up and bike runsgood with lots of get up and go so I don't worry much about these things. If I checked & it was low it would be something else to worry about.



I've done all the maintenance belts, tensioner, water pump, carbs, tires etc etc you know the drill.
 

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Well they still run well at 130 to 140 but things are going south and it will wear all that more quickly beyond 140..So it just depends how much performance is an issue for you.

Like I said Gl's will run at 100 just not with the performance that can have.
 

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My general rule of thumb on engines is that if they are good starers, idle & have good power, doesn't foul plugs or use oil then they are in pretty good shape.
An engine with one of the above symptoms is telling you it's not happy. Then you fix it or get something else. Until then drive & enjoy.
 

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Yes, I'd love to get the bike in better shape and have higher specs. The real problem here is that inorder to replace rings and/or hone cylinders...means pulling the engine and spliting the case.



There's a real quetion there if it's worth it. I've seen a lot people just look for another engine instead of going thru that expense...so maybe 130 is very exceptible in that regaurd.
 

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I would just drive it. If all the readings are around 130 and that's off a bike that has sat for awhile, those figures will improve a lot more as you drive it. Rings etc. free up with use.

Compressions testors are a diagnostic tool. If the bike is fouling plugs/running like crap than you can use one to isolate which cylinder is causing the problem.

Otherwise I wouldn't loose too much sleep over readings. You'll know soon enough if a cylinder is going bad.
 
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