Carburettor Theory

[sphen]

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.

[CYBORG]

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

[Whiskerfish]

I don't think he was using the term wrong

Goldberg is best known for his popular cartoons depicting complicated gadgets performing simple tasks in indirect, convoluted way

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.


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[CYBORG]

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.

[ericheath]

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.

[ericheath]

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This is from a Haynes manual, which at the beginning of the chapter states it has Mikuni carburetors, so who knows how reliable it is but it describes in a little more detail than my 84 shop manual.

If this isn’t readable as sometimes it is messed up in posting, I can send you a pm of the pages.

[sphen]

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

[Sidecar Bob]

General carb theory (may be helpful?) https://www.ngwclub.com/forum/viewtopic ... 34&p=90048

[Fred Camper]

Mike Nixon has material that is often helpful, nice to have both his stuff and Randalls.

[Explorer]

I don't think he was using the term wrong

Goldberg is best known for his popular cartoons depicting complicated gadgets performing simple tasks in indirect, convoluted way

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.


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I would totally agree, which is exactly why a twin choke Weber works just as well.