1000 Plenums

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redglbx
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1000 Plenums

#1

Post by redglbx »

So let me ask,,,, are all gl1000 plenum’s interchangeable & the same ? I believe they are but not sure. I am working on a carb set off an LTD for a friend that keeps leaking into the plenum, so today I found porosity & a very fine crack at the upper fuel port. Took me some time to figure where the fuel was coming from but I found it today, first time I’ve ever seen this out of the many sets of gl carbs I’ve done !

So just keep this in mind if you have a leak that you can’t seem to fix, I had fuel flowing into the plenum from the area around the number 1 carb, i have replaced the plenum gasket/seal and the carb to plenum seals (all Randakks ) several times but it still leaked and seemed to be getting worse. Even giving the good folks at Randakks a good piece of what’s left of my mind did not help relieve the leak,so we’re down to replacing the plenum, hence the question about interchangeablility. Thx guys !
Red 1976 oe owner
1976 LTD restored
1980 CBX , in the que, to fix the ignorant heavy handed owner
1981 CBX
1977 CB750 K7
2014 FJR OE owner, sold
1980 GL1100
1984 GL1200 naked
1969 CL350, in the que
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gltriker
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Re: 1000 Plenums

#2

Post by gltriker »

As I recall reading some years ago, the 1975 carburetors' flange-to-plenum connection did not utilize the 2 solid round stock alignment pins that the 1976-1979 carburetors benefit from. ( I could be wrong though? )
Last edited by gltriker on Wed Sep 14, 2022 9:52 am, edited 1 time in total.
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.
redglbx
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Re: 1000 Plenums

#3

Post by redglbx »

Thanks Cliff !
Red 1976 oe owner
1976 LTD restored
1980 CBX , in the que, to fix the ignorant heavy handed owner
1981 CBX
1977 CB750 K7
2014 FJR OE owner, sold
1980 GL1100
1984 GL1200 naked
1969 CL350, in the que
redglbx
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Joined: Tue Jun 02, 2020 8:39 am
Location: NW Indiana,

Re: 1000 Plenums

#4

Post by redglbx »

Something that has come up through all this is that the oe 76 LTD plenum has a lot of porosity in and around the fuel transfer port at the top front of the plenum by the anti-backfire valve mounting pad. I thought initially that this was just a freak occurance and then I got a replacement plenum, also a 76 that also has heavy porosity in the same area and lots of fuel staining on the outside of the plenum casting, just in the middle of the transfer port casting boss, no trail.

One other thing that shows that this probably was a leaker is that the plenum seal o’ring in that port appears to have been heavily permatex’d probably due to trying to stop a leak.

So now we’re on the third plenum, also a 76 and it is perfectly smooth with no signs of porosity at all, just perfect. So I’m wondering if this is a chronic casting problem that we’ve blamed for poor installation or a bad seals. So my advice is that if you have a leak that you can’t seem to identify or stop, take a really close look at the plenum for porosity !
Red 1976 oe owner
1976 LTD restored
1980 CBX , in the que, to fix the ignorant heavy handed owner
1981 CBX
1977 CB750 K7
2014 FJR OE owner, sold
1980 GL1100
1984 GL1200 naked
1969 CL350, in the que
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gltriker
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Location: central NY State

Re: 1000 Plenums

#5

Post by gltriker »

:worthless:
Last edited by gltriker on Sat Sep 17, 2022 12:14 pm, edited 1 time in total.
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.
redglbx
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Posts: 1116
Joined: Tue Jun 02, 2020 8:39 am
Location: NW Indiana,

Re: 1000 Plenums

#6

Post by redglbx »

Yep Cliff, totally agree , but I need to get my customer taken care of first and then I think I’ll make a test fixture and some pictures but I only have so many hours available, so I’m gonna have to circle back.

My basic point of all this is that troublesome plenum leaks seem to be a constant problem and then to get 2 in a row that show heavy porosity and evidence of leakage through that porosity ,well I guess I just thought I might save someone the headache that these 76 Ltd carbs have given me. Anyway once I get the customer taken care of I’ll take some pictures of all this,,, patience my friend 🤔😁
Red 1976 oe owner
1976 LTD restored
1980 CBX , in the que, to fix the ignorant heavy handed owner
1981 CBX
1977 CB750 K7
2014 FJR OE owner, sold
1980 GL1100
1984 GL1200 naked
1969 CL350, in the que
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pidjones
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Re: 1000 Plenums

#7

Post by pidjones »

A great aid in spotting small fuel leaks is a cheap UV flashlight. Gasoline glows bright green under one.
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redglbx
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Location: NW Indiana,

Re: 1000 Plenums

#8

Post by redglbx »

Great idea PID ! I forgot about that ! Thankyou.
Red 1976 oe owner
1976 LTD restored
1980 CBX , in the que, to fix the ignorant heavy handed owner
1981 CBX
1977 CB750 K7
2014 FJR OE owner, sold
1980 GL1100
1984 GL1200 naked
1969 CL350, in the que
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