‘79 Valves

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MattMcCoy
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‘79 Valves

#1

Post by MattMcCoy »

I recently replaced belts on a ‘79 and loosened the valves to help with that, since I wanted to check those as part of a tune-up anyway. I stumbled across Mike Nixon’s interesting blog on valve wear and wanted to try his recommendation of loosening those up to 0.006” to regain some compression.

The bike starts, idles, and revs great; however it seems to run a little rich now. My question is this: Should I continue to move along and check that the pilot screws are adjusted to 3 turns out? Wouldn’t that richen up the carbs more?

Thanks.
1983 GL1100A Aspencade
1977 GL1000
1978 GL1000
1979 GL1000

“I see Angels on Ariels in leather and chrome,
Swoopin' down from Heaven to carry me home."
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gltriker
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Re: ‘79 Valves

#2

Post by gltriker »

MattMcCoy wrote: Thu Jun 03, 2021 4:52 pm I recently replaced belts on a ‘79 and loosened the valves to help with that, since I wanted to check those as part of a tune-up anyway. I stumbled across Mike Nixon’s interesting blog on valve wear and wanted to try his recommendation of loosening those up to 0.006” to regain some compression.

The bike starts, idles, and revs great; however it seems to run a little rich now. My question is this: 1st question Should I continue to move along and check that the pilot screws are adjusted to 3 turns out? 2cd question Wouldn’t that richen up the carbs more?

Thanks.
An answer to both of your questions depends upon How many turns out from their seats are the pilot screws adjusted at, now.
Cliff (74yrs ;) )

Keep your eyes and ears open and you'll learn something new, everyday. tumb2

New users please visit our "Shop Talk" for common tips and help: <---jdvorchak
http://www.ngwclub.com/forum/page/ST
^^^^^^^click up here^^^^^ :oldies

RE: a thorough fuel tank cleaning
"And your carbs will thank you. They no longer live down stream from a sewage plant." -gregforesi tumb2
"Can't see the paint when your looking thru the handlebars..........." -Oldewing ;)
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Cliff

'75 GL1000 home built trike; http://www.ngwclub.com/forum/viewtopic.php?f=30&t=39996
October,2017 BOTM :shock: https://nakedgoldwingsclub.com/forum/page/Welcome

previous rides:
1953 H-D Servi-car, naked, 1969-1978 (serial#53G1559 committed to memory!)
1980 CB900 Custom (triked) 1997-2003 .... R.I.P.
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gltriker
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Re: ‘79 Valves

#3

Post by gltriker »

MattMcCoy wrote: Thu Jun 03, 2021 4:52 pm I recently replaced belts on a ‘79 and loosened the valves to help with that, since I wanted to check those as part of a tune-up anyway. I stumbled across Mike Nixon’s interesting blog on valve wear and wanted to try his recommendation of loosening those up to 0.006” to regain some compression.

The bike starts, idles, and revs great; however it seems to run a little rich now. My question is this: Should I continue to move along and check that the pilot screws are adjusted to 3 turns out? Wouldn’t that richen up the carbs more?

Thanks.
How many cranking compression psi were gained?
Cliff (74yrs ;) )

Keep your eyes and ears open and you'll learn something new, everyday. tumb2

New users please visit our "Shop Talk" for common tips and help: <---jdvorchak
http://www.ngwclub.com/forum/page/ST
^^^^^^^click up here^^^^^ :oldies

RE: a thorough fuel tank cleaning
"And your carbs will thank you. They no longer live down stream from a sewage plant." -gregforesi tumb2
"Can't see the paint when your looking thru the handlebars..........." -Oldewing ;)
"I'd rather Ride than Shine" -RAT tumb2 Me Too!!

Cliff

'75 GL1000 home built trike; http://www.ngwclub.com/forum/viewtopic.php?f=30&t=39996
October,2017 BOTM :shock: https://nakedgoldwingsclub.com/forum/page/Welcome

previous rides:
1953 H-D Servi-car, naked, 1969-1978 (serial#53G1559 committed to memory!)
1980 CB900 Custom (triked) 1997-2003 .... R.I.P.
MattMcCoy
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Re: ‘79 Valves

#4

Post by MattMcCoy »

Thanks, Cliff. I’ll get those numbers for you.
1983 GL1100A Aspencade
1977 GL1000
1978 GL1000
1979 GL1000

“I see Angels on Ariels in leather and chrome,
Swoopin' down from Heaven to carry me home."
redglbx
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Re: ‘79 Valves

#5

Post by redglbx »

Adjusting the valves from .004in to .006in has little to no effect, my compression gauge isn’t fine enough to show any bump so it’ll be interesting to see what Matt has. I would bet there’s no difference on a Dyno because the very small bump in compression is offset by the very small loss of valve lift.

That all said, I personally set mine at .006in simply because it’s a safer setup. On my 76 LTD that sat in a dry warehouse for probably 10-15yrs and after it was redone, running and back on the road I had a number of times that the valve clearances closed up I believe due to rust on the valve faces and/or seats and running the engine beat/lapped in and closed the clearances up. Would .006in lash have prevented that ? No, but instead of having a problem at a show 100mi away it might have got me home.

The whole debate of added performance from added compression vs lost lift is simply based on opinions, but like I said the added clearance is a little more forgiving and you may pickup a smidge of compression. Imho.
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MattMcCoy
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Re: ‘79 Valves

#6

Post by MattMcCoy »

Hey gang: I finally tested the compression after adjusting the valve lash out to 0.006in. Sorry it took so long.

The bike initially tested ~150 psi, and is now reading 175 psi on all cylinders. Unfortunately, we’ll have to take those numbers with a grain of salt, because there were too many variables between tests. I can’t confidently say that I’m seeing an increase by only adjusting valve lash. It seems the proper methodology for a true A/B would be to test immediately before and after adjustment, without any additional service or maintenance. I do feel pretty good about the current compression numbers, though.
1983 GL1100A Aspencade
1977 GL1000
1978 GL1000
1979 GL1000

“I see Angels on Ariels in leather and chrome,
Swoopin' down from Heaven to carry me home."
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gltriker
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Re: ‘79 Valves

#7

Post by gltriker »

MattMcCoy wrote: Sun Jul 11, 2021 11:21 pm Hey gang: I finally tested the compression after adjusting the valve lash out to 0.006in. Sorry it took so long.

The bike initially tested ~150 psi, and is now reading 175 psi on all cylinders. Unfortunately, we’ll have to take those numbers with a grain of salt, because there were too many variables between tests. I can’t confidently say that I’m seeing an increase by only adjusting valve lash. It seems the proper methodology for a true A/B would be to test immediately before and after adjustment, without any additional service or maintenance. I do feel pretty good about the current compression numbers, though.
Thanks for the information, Matt. tumb2
I can't scoff at the improvement. I could write a lengthy testimonial to the very measurable increase in individual cylinders' cranking compression test results on my 1975 GL1000 trike's very good internal condition engine, and a real world, on a paved highway, overall engine performance improvement with the 0.002" larger valve lash clearance adjustment, only.
Definitely not laughable bench racing musings. ;)
Cliff (74yrs ;) )

Keep your eyes and ears open and you'll learn something new, everyday. tumb2

New users please visit our "Shop Talk" for common tips and help: <---jdvorchak
http://www.ngwclub.com/forum/page/ST
^^^^^^^click up here^^^^^ :oldies

RE: a thorough fuel tank cleaning
"And your carbs will thank you. They no longer live down stream from a sewage plant." -gregforesi tumb2
"Can't see the paint when your looking thru the handlebars..........." -Oldewing ;)
"I'd rather Ride than Shine" -RAT tumb2 Me Too!!

Cliff

'75 GL1000 home built trike; http://www.ngwclub.com/forum/viewtopic.php?f=30&t=39996
October,2017 BOTM :shock: https://nakedgoldwingsclub.com/forum/page/Welcome

previous rides:
1953 H-D Servi-car, naked, 1969-1978 (serial#53G1559 committed to memory!)
1980 CB900 Custom (triked) 1997-2003 .... R.I.P.
MattMcCoy
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Re: ‘79 Valves

#8

Post by MattMcCoy »

No problem, Cliff. Just for the record, I don’t doubt anyone’s experience/expertise with a gain in compression by loosening valve lash, just that I didn’t follow protocols for a proper A/B test that I could vouch for.
1983 GL1100A Aspencade
1977 GL1000
1978 GL1000
1979 GL1000

“I see Angels on Ariels in leather and chrome,
Swoopin' down from Heaven to carry me home."
MikeNTexas
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Re: ‘79 Valves

#9

Post by MikeNTexas »

Maybe an increase in compression by increasing the lash could be connected to a reduction in the overlap time when the intake and exhaust are both open at the top of the exhaust stroke.
1975 GL1000 Restored (sold)
1983 GL1100 Custom (sold)
1976 GL1000 Project (finished and sold)
Another1976 GL1000 Project (finished and sold)
MattMcCoy
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Re: ‘79 Valves

#10

Post by MattMcCoy »

Thanks, Mike. That’s also my understanding.
1983 GL1100A Aspencade
1977 GL1000
1978 GL1000
1979 GL1000

“I see Angels on Ariels in leather and chrome,
Swoopin' down from Heaven to carry me home."
Shadowjack
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Re: ‘79 Valves

#11

Post by Shadowjack »

Increasing or decreasing the valve lash used to be a fine-tuning tool for people looking for the last gnats-ass increase in performance, i.e., drag racers. Solid lifter cams only, of course. Not a long-term thing, though.
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ericheath
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Re: ‘79 Valves

#12

Post by ericheath »

Whether at 0.004” or 0.006”, the valve is closed. Is the theory that expansion of parts may be more than the 0.04”??? Thus holding the valve slightly open?

If at 0.004” on a cold engine, wouldn’t you get the same readings as 0.006” if you compression checked it? It hasn’t been able warm up yet.
Whatever I suggest here should be given ample time for a moderator to delicately correct. I apologize in advance.
77 WING, 1200 engine with 77 heads, cams, gl1100 foot pegs, Magna V65 front end, 764A carbs, [-gone Suzuki M109 monoshock--, replaced with gl1100 shocks] gl 1200 swing arm, gl1500 final drive, wheel and rear brakes Valkyrie seat, Meanstreak tank, Sportster pipes, Power Arc ignition off crank.
77 Wing. black
83 Wing, in pieces
"Continuing education is important even if the subject matter is fairly useless (as in this case)."---Greg Foresi
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robin1731
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Re: ‘79 Valves

#13

Post by robin1731 »

ericheath wrote: Wed Jul 14, 2021 3:09 pm Whether at 0.004” or 0.006”, the valve is closed. But it is closed longer for the same amount of crankshaft rotation. The piston gets more time to compress the charge. Is the theory that expansion of parts may be more than the 0.04”??? Thus holding the valve slightly open?

If at 0.004” on a cold engine, wouldn’t you get the same readings as 0.006” if you compression checked it? It hasn’t been able warm up yet.
Same as if you use a cam with less lift and or duration than you already have in the engine. You'll get more cranking compression with a smaller cam if nothing else is changed. Opposite would be true if you used a cam with more lift and or duration.

Someone mentioned valve overlap earlier. That too can make a difference. But with a single overhead cam the cam has to be ground with a certain/set amount of overlap. With dual overhead cams you move each cam around and change the overlap.
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and a rotation of various purchases
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gltriker
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Re: ‘79 Valves

#14

Post by gltriker »

Mike Nixon has presented numerous articles that recommend increasing intake and exhaust valves' lash clearance to 0.006" on our GL1000 engines, and why.
In the article linked to below from July, 2017, I asked more than a few questions about the effect that seemingly tiny increase in valve lash clearance imparts to increase cranking compression test readings. As the conversation continued, Mike provided graphic representations of slightly altered valve dynamics resulting from the 0.002" valve lash clearance increase.
Although most of them went over my comprehension , employing his advice made me a believer. ;)

https://ngwclub.com/forum/viewtopic.php?f=54&t=63468 .
Cliff (74yrs ;) )

Keep your eyes and ears open and you'll learn something new, everyday. tumb2

New users please visit our "Shop Talk" for common tips and help: <---jdvorchak
http://www.ngwclub.com/forum/page/ST
^^^^^^^click up here^^^^^ :oldies

RE: a thorough fuel tank cleaning
"And your carbs will thank you. They no longer live down stream from a sewage plant." -gregforesi tumb2
"Can't see the paint when your looking thru the handlebars..........." -Oldewing ;)
"I'd rather Ride than Shine" -RAT tumb2 Me Too!!

Cliff

'75 GL1000 home built trike; http://www.ngwclub.com/forum/viewtopic.php?f=30&t=39996
October,2017 BOTM :shock: https://nakedgoldwingsclub.com/forum/page/Welcome

previous rides:
1953 H-D Servi-car, naked, 1969-1978 (serial#53G1559 committed to memory!)
1980 CB900 Custom (triked) 1997-2003 .... R.I.P.
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ericheath
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Re: ‘79 Valves

#15

Post by ericheath »

“ Although most of them went over my comprehension ”. Cliff, I can totally relate. I recall Mike’s article. And scratching my head the same as trying understand the differences in static and dynamic valve testing.
Whatever I suggest here should be given ample time for a moderator to delicately correct. I apologize in advance.
77 WING, 1200 engine with 77 heads, cams, gl1100 foot pegs, Magna V65 front end, 764A carbs, [-gone Suzuki M109 monoshock--, replaced with gl1100 shocks] gl 1200 swing arm, gl1500 final drive, wheel and rear brakes Valkyrie seat, Meanstreak tank, Sportster pipes, Power Arc ignition off crank.
77 Wing. black
83 Wing, in pieces
"Continuing education is important even if the subject matter is fairly useless (as in this case)."---Greg Foresi
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