Real world cylinder compression?

Discuss everything about Honda GoldWing. Feel free to ask any question related to GoldWing.

Moderators: CYBORG, robin1731, Oldewing, Forum Moderators

Post Reply
redglbx
Titanium Member
Titanium Member
Posts: 444
Joined: Tue Jun 02, 2020 8:39 am
Location: NW Indiana

Re: Real world cylinder compression?

#16

Post by redglbx »

Thanks Cliff ! I don’t 100% agree with Mike (great asset here) as I’ve been doing this as well for over 50yrs but he does make sense and I certainly don’t totally disagree. Thinking about it, by increasing the valve clearances effectively reduces the cam timing duration so it will increase the compression, should also show a slight power loss on a dyno. advancing the cams like I did also gives a pretty big bump in compression And a low end torque bump with really no loss of top end due to the 75-77 cams being fairly radical and their power peak really happens above redline so advancing them brings it within the redline.

But all this still doesn’t fit with when my Wing-was new in 76 and I checked the compression within the first 100-200mi and it was at 135-140psi brand new. It stayed that way until I milled the.040in off the heads and advanced the cams 4deg. Advancing them +6deg was really a bit to much because the motor would really fall off above 7500-7800rpm.

Anyway thanks for replying and I hope my rant wasn’t too boring or annoying, thx
User avatar
gltriker
Honored Life Member
Honored Life Member
Posts: 4048
Joined: Fri Sep 24, 2010 9:11 pm
Location: Baldwinsville, NY (central NY)

Re: Real world cylinder compression?

#17

Post by gltriker »

redglbx wrote: Thu Nov 25, 2021 1:41 pm Thanks Cliff ! I don’t 100% agree with Mike (great asset here) as I’ve been doing this as well for over 50yrs but he does make sense and I certainly don’t totally disagree. Thinking about it, by increasing the valve clearances effectively reduces the cam timing duration so it will increase the compression, should also show a slight power loss on a dyno. advancing the cams like I did also gives a pretty big bump in compression And a low end torque bump with really no loss of top end due to the 75-77 cams being fairly radical and their power peak really happens above redline so advancing them brings it within the redline.

But all this still doesn’t fit with when my Wing-was new in 76 and I checked the compression within the first 100-200mi and it was at 135-140psi brand new. It stayed that way until I milled the.040in off the heads and advanced the cams 4deg. Advancing them +6deg was really a bit to much because the motor would really fall off above 7500-7800rpm.

Anyway thanks for replying and I hope my rant wasn’t too boring or annoying, thx
:lol: Nope
Cam, ;)
Read all 3 pages of Mike Nixon's, "Five must-haves for a good-running GL1000" topic.
I have and discovered there was a Lot More meaningful discussions and technical data presented in those 3 pages than I remembered. tumb2

question: how did you advance the cam timing? an offset pulley indexing key or some such modification in that area ?
Last edited by gltriker on Sun Nov 28, 2021 2:07 am, edited 2 times in total.
Cliff

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.
redglbx
Titanium Member
Titanium Member
Posts: 444
Joined: Tue Jun 02, 2020 8:39 am
Location: NW Indiana

Re: Real world cylinder compression?

#18

Post by redglbx »

Cliff, I had a local guy EDM key ways in at 2,4 & 6deg. If I was to do it all over again, I’d just have it done at +4deg on the crank pulley instead of the cam pulley’s. But I was experimenting and dyno’d it after the changes , plus I wanted to see if there was anything in being able to advance or retard one side vs the other, nothing there. Compression is the real indicator of the results.

I’ll add that the +4 gave me a very flat power curve that only varied from peak torque 2 ft/lb from 2200-6800rpm. Horsepower was also pretty flat but did loose 2hp off of the peak. It really doesn’t feel faster because there’s no peak/surge/on the cam feel, it just pulls.

Iplay with the cams on everything anymore, just to much to be gained, on the double overhead cam bikes (cbx’s) advancing the intakes but just putting the exhaust straight up gives a really nice flat curve with a really nice power bump on both torque and hpwer, but the wings are just single cams. If I had unlimited funding I would have custom cams ground with just the intakes advanced but the exhaust just straight up. I’ve modeled the GW engine on a computer simulation program to find improvements and found really not much in the cams past the advancing them. I feel good about the modeling as the actual dyno work repeated the predicted results nearly exact. I feel good about the results.
User avatar
gltriker
Honored Life Member
Honored Life Member
Posts: 4048
Joined: Fri Sep 24, 2010 9:11 pm
Location: Baldwinsville, NY (central NY)

Re: Real world cylinder compression?

#19

Post by gltriker »

gltriker wrote: Wed Nov 24, 2021 7:44 pm For truest testing results, utilize a 12mm threads compression testing adaptor that screws directly into the spark plug hole.
20191213_204517_1637796073345_resized (1).jpg


regarding a Best Practice set-up, 14mm threads-to-12mm threads compression testing reducers are not X recommended

20200112_113223_1637982760730_resized (2).jpg
by removing its check valve, this cylinder compression testing adaptor converts to a cylinder leakdown testing adaptor, too. tumb2
The example of a 12mm compression testing adaptor hose assembly I had presented in my post# 13 is a Snap-On product.
I unexpectedly snagged it (stole it, actually), from a seller on eBay around 2 years ago. anyways.........

A far less expensive alternative is a 12mm testing hose assembly which is available from Motion Pro. part number 08-126Y
Its product description is: MOTION PRO #08-126Y – 4-STROKE LEAK DOWN TESTER REPLACEMENT 12MM HOSE

Yes, it is described as a Leak Down Tester Hose, but it already has internal threads machined into the 12mm end to accept the installation of a Schrader style check valve assembly, too. A valve stem core, if you will. Motion Pro calls it a Snifter Valve.
Motion Pro will sell you a 'Snifter Valve' . Save your money! Install a good old Schrader valve . Same thing.

Done tumb2
Last edited by gltriker on Mon Nov 29, 2021 6:28 pm, edited 2 times in total.
Cliff

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.
User avatar
kerryb
Cast Iron Member
Cast Iron Member
Posts: 59
Joined: Sat Jan 24, 2015 1:11 pm
Location: Buffalo, NY

Re: Real world cylinder compression?

#20

Post by kerryb »

Just two compression examples to add, my '83 with 120k miles and a serious rod knock ran smooth and strong with 90+ psi compression ( good power, just a nasty noise). A '77 I'm working on now measured 150 on all 4 after 10 minutes of run time after a long sleep. Apparently it had been well cared for during it's 48k miles.
intrigued by the wail...seduced by the scream.
'78 cb750K, '83 GL1100s,I,&A,'08FXSTC, '79 WilMac trike
Post Reply

Return to “GoldWing Tech Discussions”