Low compression - Steve Saunders Goldwing Forums

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post #1 of 32 (permalink) Old 06-18-2018, 07:21 AM Thread Starter
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Low compression

Hey guys Iím hoping someone here can help. I picked up a 98 Valkyrie (which is based off the 1500) to replace my GL1200.

It has 30k miles (and I hope not 130k!) it pulls hard but after a valve adjustment I checked the compression.

1: 112
2: 87 (got it to 90 w penetrating oil)
3: 105
4: 97
5: 118
6: 115

How concerning is this?

2 and 4 are next to each other with 6 behind them. Not sure if that means anything but just making note of the fact.

These bikes are prone to hydrolock from a faulty petcock.

All valves were either in spec or just one feeler gauge away from spec with the exception of #2 which was .002 too lose (2 feeler gauges out).

I think my next step is either seafoam or marvel mystery oil in the crankcase.

Iím really hoping itís just carbon but from what?
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post #2 of 32 (permalink) Old 06-18-2018, 08:09 AM
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I'd go with the Seafoam or MMO in the oil idea, then change the oil after 50 to 100 easy miles. Even some Seafoam in the gas. When an engine has sat for a while, the rings may need some exercising. Rider 'er for a while and reevaluate.

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post #3 of 32 (permalink) Old 06-18-2018, 09:23 AM
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Quote:
Originally Posted by theRide View Post
...
It has 30k miles (and I hope not 130k!) it pulls hard but after a valve adjustment I checked the compression.

1: 112
2: 87 (got it to 90 w penetrating oil)
3: 105
4: 97
5: 118
6: 115

How concerning is this?

2 and 4 are next to each other with 6 behind them. Not sure if that means anything but just making note of the fact. ?
Well... unfortunately those are ALL low compression readings.

(You did have your throttle locked all the way open when you did the test, right?)

The factory service manual gives a spec of 213 psi for a normal GL1500 engine. The compression test range given in the FSM is 185 psi to 242 psi.

You would only have a reading above 220 or so if you have a really carbon fouled engine. Your current reading are ALL low, so carbon is not the issue.

Low compression can come from three main areas:

1. Worn piston rings
2. Worn/leaking valve seats
3. Leaking cylinder head gaskets

The only sure way to tell exactly what is leaking is to do a leak-down test with a cylinder leak-down tester. A compression tester only tells you if your compression is low. A leak-down tester tells you why. A leak-down tester charges the cylinder being tested with compressed air from an air compressor. Any leak-down percentage results greater than about 8% is a problem. Also, during the test you can listen to where the air is escaping from the engine which will tell you if its rings or valves. If air is escaping through the exhaust system, the exhaust valves are leaking. If air is escaping through the intake/air filter, the intake valves are leaking. If air is escaping through the crankcase, the piston rings are leaking.

I would suspect that the two cylinders that are REALLY low (and next to each other) probably have a leaking cylinder head gasket and the leak is between those two cylinders. All the rest being low could be stuck rings (put in some ring free fluid (like YamaLube Ring Free Fuel additive) and ride that baby! However, it could also be worn rings in the entire engine, which additives will not fix.

Be sure to check your engine oil and see if it looks at all milky. If it does, STOP RIDING the bike until that is fixed! If the oil is milky your cylinder head gasket is leaking and engine coolant is getting into the oil. Note that you can have a cylinder head leak that only leaks to the outside and not into the coolant passages, in which case your oil would look OK, but you could still have low compression in those cylinders.

Even if your bike does have 130,000 miles on it and not 30,000 that should not be an issue with a water cooled Gold Wing engine, unless it was not receiving proper maintenance and oil changes.

A cylinder head gasket replacement is not that hard on a Gold Wing. It does require removing the timing belts, but unless you know when those were last changed, you should change those belts when you do the head gasket.

A Valkyrie is a great Gold Wing! They look bad-azz too! Take your time and and get yours fixed up properly.

**
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Bob
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post #4 of 32 (permalink) Old 06-18-2018, 11:00 AM Thread Starter
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Thank you Wingman!!!

I did not do any of the compression checks with WOT except number two to see if I could get it to come up.

I didnít know enough of diagnostics to be concerned with getting max pressure I just wanted to see if I could get consistent numbers.

Now I see that itís important that I do it WOT to get a real read.

So if I understand correctly I can try the yamalube additive so long as I donít see evidence of moisture in my oil (milky white) on the oil cap. Iím also going to try cracking the oil plug and seeing if I get any coolant (oil floats on water).

I currently am on my second tank of Berrymans B-12

https://www.berrymanproducts.com/pro...ector-cleaner/.

Once that is done should I try the Yamalube additive?

Or do you think I should be performing a leak down test? Im hoping just riding it will improve things. Iíve only done 150 miles since purchase.
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post #5 of 32 (permalink) Old 06-18-2018, 11:12 AM
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Quote:
Originally Posted by theRide View Post
Thank you Wingman!!!

I did not do any of the compression checks with WOT except number two to see if I could get it to come up.

I didnít know enough of diagnostics to be concerned with getting max pressure I just wanted to see if I could get consistent numbers.

Now I see that itís important that I do it WOT to get a real read.

So if I understand correctly I can try the yamalube additive so long as I donít see evidence of moisture in my oil (milky white) on the oil cap. Iím also going to try cracking the oil plug and seeing if I get any coolant (oil floats on water).

I currently am on my second tank of Berrymans B-12

https://www.berrymanproducts.com/pro...ector-cleaner/.

Once that is done should I try the Yamalube additive?

Or do you think I should be performing a leak down test? Im hoping just riding it will improve things. Iíve only done 150 miles since purchase.
OK...

FIRST, check the oil and make sure there is no coolant in the oil. If there is, then don't ride the bike anymore until you've corrected that by replacing the cylinder head gasket(s).

SECOND, you should get higher compression readings with the throttle held at wide open during the test, but probably only 5 to 10 psi different, so you may still have an issue with low compression. But, do the test anyway and see.

THIRD, you don't have to pull the crankcase plug and let some oil leak out to check to see if there's coolant in it. Sometimes, if you can get at the radiator cap easily, you can just look in there and see. You can also just unscrew the oil filler cap and stick a straw or small diameter hose down into the crankcase and suck some out to have a look at it.

FOURTH, if NO coolant in the oil and the engine runs well even with the low compression, then put some YamaLube Ring Free additive in the gas and ride at least a hundred miles or more to let that work on the rings. Then check the compression again (with a warm engine).

If you still have low compression, it would be good to know why. The only way to determine that is with a cylinder leak-down test.

Good luck with it.

***

Bob
2006 Arctic White GL1800
1987 Black/Grey GL1200 Aspencade
1976 Special Candy Maroon GL1000 LTD
U.S. Navy SWO (1967-1976)
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post #6 of 32 (permalink) Old 06-18-2018, 11:20 AM
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I suspect you did the test wrong, and you shouldn't do anything else until you do the test right. Motor warm and wide open throttle.
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post #7 of 32 (permalink) Old 06-18-2018, 11:34 AM
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If it even 130 k on it,I doubt the compression would be all over the place on these motors ,they just dont fail in that short a time.Just put the Yamalube in it and go ride that bad boy,does it have the stock exhaust?the aftermarket pipes are annoying loud.
I’ve never adjusted the valves on one of these motors but is there a chance you made an error on setting.

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post #8 of 32 (permalink) Old 06-18-2018, 11:54 AM
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Get yourself a set of "step" or "no-go" feeler gauges and run the valves again. As a general rule, clearances tend to get tighter (not looser). Then do a compression test the correct way. If your numbers are still wacked, do a leak down. .005 too loose is better than .001 too tight. But neither are right.
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post #9 of 32 (permalink) Old 06-19-2018, 10:30 AM
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Agree with Glhonda on valve adjust. Did you check to see if pulleys align with timing marks? One tooth off could raise heck with numbers and performance.
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post #10 of 32 (permalink) Old 06-19-2018, 05:07 PM Thread Starter
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Low compression

It has the stock exhaust and itís plenty loud for me.

I checked for coolant in oil with a piece of aquarium airline tubing and under radiator cap and in the reservoir for signs of oil. Nada!

I did not check the timing belt alignment but will.

On the subject of valve adjustment: how off is off?

For instance if I tightened a valve so that the feeler gauge drags but moves freely when I push on the back side of the lifter is that much too tight it negligible?

As I understand it now too lose is better than too tight. Just wondering how mad I should drive myself seeking perfection!

Also what torque should I apply to the locknuts?

I went to harbor freight to pick up a leak down tester. Unfortunately the reviews are correct and the air fitting is not standard and they didnít have another that fits the threaded bore on the tool.

I picked up a boroscope. Nothing of note except a couple of scratches (see pic).

I also recalled when doing the prepurchase inspection there was a knock. I was concerned but by the time I got a long screwdriver to listen through it to the various areas it had vanished and has not returned.

Iím waiting on amazon for the yamalube ring free additive. In the meantime I threw seafoam into the crankcase. I then rode it with a lot of hard and high acceleration and throttle chops. (Still on the tank of Berrymans B12 in the fuel).

I suspect itís just rings hanging up fingers crossed.



Thank you all for the great tips and advice. Iíll keep digging!
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