Carburettor Theory
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Carburettor Theory
Mornin-
I've started disassembling this rube goldberg device aka gl1200 carb rack, and was wondering if someone would be willing to talk me through some of the functions and features of the rack itself. I understand carb basics like venturi, the various jets, needles, and circuits, but I'm not clear what the PCV, anti afterburn, reed valves, secondary supply, etc do in this context. Ive never dealt with more than one unit at a time before, so some of those "newer" features are lost on me.
tks.
I've started disassembling this rube goldberg device aka gl1200 carb rack, and was wondering if someone would be willing to talk me through some of the functions and features of the rack itself. I understand carb basics like venturi, the various jets, needles, and circuits, but I'm not clear what the PCV, anti afterburn, reed valves, secondary supply, etc do in this context. Ive never dealt with more than one unit at a time before, so some of those "newer" features are lost on me.
tks.
Project bike "Dixie" - 1986 GL1200 Aspencade being rebuilt from ground up to be a naked 'wing. Build progress thread here: viewtopic.php?f=30&t=71959
Build log video: View it here
BOTM November '22
Build log video: View it here
BOTM November '22
- CYBORG
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Re: Carburettor Theory
Rube Goldberg???? More like one of the most advanced, and sophisticated devices of it's time. Suggest you get a manual, or instruction book. I m ight suggest the Randakk kit, which comes with really good instructions. And after you have done them and redone them a few times, you will ,understand them. And maybe appreciate the way they work
1978 custom GL1000
1977 custom with 1200 engine
1985 gl1200
1977 custom with 1200 engine
1985 gl1200
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Re: Carburettor Theory
I don't think he was using the term wrong
.
I believe the anti after burn is a upgrade to the air cut off valve. Basically it balances the mixture when decelerating to prevent after fires. The others will have to wait for someone with more knowledge than I.Goldberg is best known for his popular cartoons depicting complicated gadgets performing simple tasks in indirect, convoluted way
.
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"The book is wrong, this whole Conclusion is Fallacious" River Tam
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2008 GL1800 IIIA "TH3DOG"
1984 GL1200 Standard
1975/6/7/8/9 Arthur Fulmer Dressed Road bike
1975 Naked Noisy and Nasty in town bike
Psst. oh and by the way CHANGE YOUR BELTS!!!!
"The book is wrong, this whole Conclusion is Fallacious" River Tam
"Yea I do dance awkwardly, and I am having more fun than you" Taylor Swift
2008 GL1800 IIIA "TH3DOG"
1984 GL1200 Standard
1975/6/7/8/9 Arthur Fulmer Dressed Road bike
1975 Naked Noisy and Nasty in town bike
Psst. oh and by the way CHANGE YOUR BELTS!!!!
- CYBORG
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Re: Carburettor Theory
I would question if there is any easier way to accomplish the smooth transition over the RPM range, short of fuel injection of course, and have the great look that the Goldwing carb rack has, considering when it was designed.
1978 custom GL1000
1977 custom with 1200 engine
1985 gl1200
1977 custom with 1200 engine
1985 gl1200
- ericheath
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Re: Carburettor Theory
I assumed the reeds and secondary air supply were just to keep oxygen levels up and pass EPA tests. It still has an air cutoff valve, but I’m really not sure how they all work together.
Others and myself have removed and plugged the reed valves and air hoses and plugged the holes going to the exhaust. I have the cutoff valve back on but however I have it hooked up doesn’t help.
Mine works fine except for enrichment for what the air cutoff does on other years. If mine is bad enough, I simply slide the choke lever a little forward when slowing down. The backfiring is really not bad unless you’re up in rpm and let off or downshift for braking.
Others and myself have removed and plugged the reed valves and air hoses and plugged the holes going to the exhaust. I have the cutoff valve back on but however I have it hooked up doesn’t help.
Mine works fine except for enrichment for what the air cutoff does on other years. If mine is bad enough, I simply slide the choke lever a little forward when slowing down. The backfiring is really not bad unless you’re up in rpm and let off or downshift for braking.
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
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
- ericheath
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Re: Carburettor Theory
If this isn’t readable as sometimes it is messed up in posting, I can send you a pm of the pages.
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
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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Re: Carburettor Theory
ah thats helpful - i have the honda manual and the clymer manual, and both are all business no explanation (as expected). just looking for more detail on what those sub-systems do.
and yes, i rest on my goldberg statement :-p
and yes, i rest on my goldberg statement :-p
Project bike "Dixie" - 1986 GL1200 Aspencade being rebuilt from ground up to be a naked 'wing. Build progress thread here: viewtopic.php?f=30&t=71959
Build log video: View it here
BOTM November '22
Build log video: View it here
BOTM November '22
- Sidecar Bob
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Re: Carburettor Theory
General carb theory (may be helpful?) https://www.ngwclub.com/forum/viewtopic ... 34&p=90048
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The Famous Eccles ('84 CX650EI/VeloUral) winter Never Ending Build (CX500forum)
Click: Colour schematics for all GL1000 & GL1100 and GL1200 standard models plus instructions on how to download the full size version
"A guy with two sidecars can't be all bad." - Cookie
Another guy with two sidecars..... Hmmmm... must be something to that....
The Famous Eccles ('84 CX650EI/VeloUral) winter Never Ending Build (CX500forum)
Click: Colour schematics for all GL1000 & GL1100 and GL1200 standard models plus instructions on how to download the full size version
"A guy with two sidecars can't be all bad." - Cookie
Another guy with two sidecars..... Hmmmm... must be something to that....
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Re: Carburettor Theory
Mike Nixon has material that is often helpful, nice to have both his stuff and Randalls.
Last edited by Fred Camper on Mon Mar 16, 2020 10:53 pm, edited 1 time in total.
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1976 LTD - '993 LTD...and so it begins'
You should remember that it's peace of mind you're after and not just fixing the machine. R.Pirsig
1977 GL1000 BADDOG (April 2012 BOTM)
1976 LTD - '993 LTD...and so it begins'
You should remember that it's peace of mind you're after and not just fixing the machine. R.Pirsig
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Re: Carburettor Theory
I would totally agree, which is exactly why a twin choke Weber works just as well.Whiskerfish wrote:I don't think he was using the term wrong
I believe the anti after burn is a upgrade to the air cut off valve. Basically it balances the mixture when decelerating to prevent after fires. The others will have to wait for someone with more knowledge than I.Goldberg is best known for his popular cartoons depicting complicated gadgets performing simple tasks in indirect, convoluted way
.
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