I dislike carburetors.

[Idaho45guy]

Bought a `94 Road King. It came with an aftermarket S&S Super E carb that sat too long in the Arizona heat and was gummed up.

Took it apart and the inside is pretty bad. Rebuild kit was $90. New S&S carb is $350. Chinese copy of S&S carb with good reviews was $70. Bought the Chinese carb and installed it.

Turned on the fuel and gas immediately started leaking out of the inlet fitting. Bad O-ring. Took the fitting off of the S&S carb and installed it. Tried again. Fuel started pouring out of the fuel overflow tube.

Went to church and talked to a Harley expert. He said the float, or the needle and seat have issues. He said to take it apart and check everything inside. He said the Chinese carbs are usually pretty good but just need a bit of tweaking.

I hate tweaking. Mainly because my brain in incapable of understanding two things; algebra and carburetors.

But, only one motorcycle shop in the region and they are booked out for months, and the guy at church is also months behind in his obligations.

So, I will be spending the afternoon on YouTube and in my garage trying to figure out this thing.

[uscra112]

Even a tiny bit of dirt in the needle seat is all it will take to make the carb flood, but I have also had carbs where the float was not completely free. One I can remember was dragging on the side of the bowl, others were tight on the pivot. Once in a great while we'd find a float that wasn't airtight, and had gotten fuel inside it, whereupon it "sank". A lot of floats today are plastic, even foam, but in those days they were soldered up out of thin brass sheet.

[ascast]

I have bought Chinee carbs for chainsaws and old JD garden tractors. They seem to be real junk. On one the needles could be screwed into full off or taken out and there was no difference in the running. I think your better off getting somebody to rebuild it. The Chinee can copy anything, but only so much as it is a paper weight that looks simliar

[Handloader109]

You gets what youse pay for. $70 for something that will most probably work better than the old one, but never work quite right, or $350 for one you can put on and just drive off. Yeah, I know, no one wants to pay 5 times more for something, but you gets what youse pay for.

Sent from my SM-G892A using Tapatalk

[beezapilot]

Look around for a shop with an ultrasonic cleaner, try the local airport OR a marina if you have one WHEN YOU TAKE IT APART COUNT THE REVOLUTIONS ON THE JETS / ADJUSTERS!!!!!!!!!!!!!! An ultrasonic will clean it up and spare the O rings should they be salvagable. It may not be as bad as you think! DON"T DIP IT IN CAUSTIC CHEMICALS.

[NyFirefighter357]

Chinese carburetor, enough said!

[Finster101]

Chinese carburetor, enough said!

Almost the whole cost of the rebuild kit.

[uscra112]

I've had good luck (so far) with Chinese replacements for my Stihl weedwhackers. Whole carb is half the price of the rebuild kit from Stihl.

[Finster101]

I've had good luck (so far) with Chinese replacements for my Stihl weedwhackers. Whole carb is half the price of the rebuild kit from Stihl.

Your weed whacker isn't something you might depend on to get you home.

[Markopolo]

I hate em too…

[45DUDE]

The China carbs will work for a while then the rubber rots. I had overhauled over 40000 carburetors in 45 years before I sold my shop. I still do some every once in a while. Its hard to get a girl when you smell like carburetor cleaner. If one gets friendly they usually look like the ones on Street Outlaws.

[Idaho45guy]

The China carbs will work for a while then the rubber rots. I had overhauled over 40000 carburetors in 45 years before I sold my shop. I still do some every once in a while. Its hard to get a girl when you smell like carburetor cleaner. If one gets friendly they usually look like the ones on Street Outlaws.

My experience with the Chinese dune buggy I bought as well. Not even a year later in Arizona, the rubber all disintegrated and the paint turned to powder. Hoping this carb will last long enough to get a new S&S.

Got it running and figured out the problem(s).

First, the needle wasn't even attached to the float! It must have fallen off being shipped. Then when I did attach it, the original S&S seat was so gummed up that the needle stuck.

So, I took some metal polish, stuck a Q-tip in a drill, and went to town on it.

298248

298249

There was also a bunch of grit inside the carb when I took it apart...

298250

Got the needle and seat happy, then adjusted the float level. It was about a 1/4" off. Then I re-set everything to original S&S parameters.

Bike fired right up. Got the idle adjusted, then rode it around town to get it warmed up. Then did a basic tune on it and got it running pretty darn good.

Took it for a trip a few miles out of town and took a video of it...


https://youtu.be/liIEkksMCXU

Exhaust still smells a little rich. I suspect one of the plugs is fouled again. Ordered new ones and added 2.5 gallons of premium ethanol-free 91 octane gas. $13 dollars!!

[45DUDE]

Man that sounds good. Like a top fuel dragster. The more you screw the mixture screw in the less the smell. If you are going to let it set for a while let the carb run out of gas. I have never owned a Harley other than a dirt bike <on and off road>but my friend Ray has about 20 and none newer than yours and The local Harley dealer is a friend of mine.

[megasupermagnum]

I'm not a Harley expert, or even all that familiar with them. I have never heard anyone say good things about the knockoff Harley carbs. A big reason the S&S's are so expensive is the name, but there's also a lot required to make a big 4 stroke engine run smooth, start cold, start hot, and crack it without bog like they do. There are cheaper rebuild kits around if you look. You don't need those $75 kits, most of which is stuff you don't need to replace.

Yeah, you can sometimes, but not always get away with a $15 China carb on a little 2 stroke engine. That's a whole different ball game. 2 strokes are much easier to deal with. They don't have hot or cold starting issues, and they have a stronger impulse, they don't need accelerator pumps to rev. A 2 stroke carburetor is nothing but a barely controlled leak.

P.S. Don't bother with carb dips. They are trash. Dawn and water is stronger than those stupid things. If you want real carb cleaner, buy B12 Chemtool. That stuff will eat nitrile gloves, it's the real deal.

[samari46]

I remember my grade school teacher that said algebra will help you later on in life. Well at 75 I'm still waiting. Craftsman riding lawn mower dropped the front of the deck on the ground. Has a bracket on the front of the deck and another under the engine. Have the spring that goes on the two brackets. Need to be Arnie to stretch the spring. Ordered the manual from sears. Figured it was a done deal. Wednesday they cancelled the order and refunded my money. No reason given. Will be calling MTD monday to see if they have the manual. 75 years old laying on the ground with a flashlight to see what goes where. Now that has to be harder than algebra. Frank

[45DUDE]

I remember my grade school teacher that said algebra will help you later on in life. Well at 75 I'm still waiting. Craftsman riding lawn mower dropped the front of the deck on the ground. Has a bracket on the front of the deck and another under the engine. Have the spring that goes on the two brackets. Need to be Arnie to stretch the spring.. Frank If it's the spring for the belt tensioner pulley you have to have the belt loose to install the spring.

[rbuck351]

I like carbs with the exception of the pumper carbs. Bought cheap or was given several things with carb problems. Cleaning the carb usually fixes things but sometimes there are broken parts that can't be fixed. I have replaced four or five carbs that can't be fixed with cheap China carbs and all have worked fine. Years ago I worked as a motorcycle mechanic in a Honda shop. Synchronizing the first CB750s 4 carbs without the fancy gauges was a real experience. They would rev like mad without accelerator pumps and then drop to a dead smooth idle when adjusted properly. Idle speed, air mixture and throttle opening all had to be even across all four carbs.

And yes, if you are going to get carb cleaner , the B12 is the best. Lacquer thinner works fair but not in the same class as B12.

[uscra112]

The first ones didn't even have that lever linkage - one cable into four that never STAYED synched even if you got them that way in the shop. Triumph/BSA led the way there for a little while.

[Idaho45guy]

My `65 GTO originally came from the factory with a 389 and three 2bbl carbs. The guy I bought it from replaced the 389 with a 428 and an 850 Holley Double-Pumper. That motor put out over 500 hp. He said the stock set-up was a pain to keep running right.

[brass410]

twenty years from now this thread will start off " I hate batteries" the whole thread will be filled with electrified annecdotes about past connections and conductivity issues!!!!!

[Texas by God]

I had a friend that would rebuild carburetors on his kitchen table for a twelve pack of Bud.
I gladly brought him beer with the side draft SU units from a Volvo that I had. He was delighted to get something different to work on.
RIP, Borrego!

Sent from my SM-A716U using Tapatalk

[Harter66]

It's funny every says "I've never used algebra" .
Balance a check book , buy multiple items , land/groove , paper wrap length ......... Our brain does about 500 trig operations so we don't stab ourself in the lip or forehead eating with a fork ......

My Dad rebuilt a bunch of carbs , I replaced a few needle and seats and fixed a few idle cut off valves/switches . Mostly I wash bowls and idle jets out .

Even the GL1000 that wouldn't idle cleaned up just washing out the jets . If the shafts are leaking that's another thing all together . There's probably nothing wrong with the carb you pulled filling it up with B12 or dropping the bowl/off and washing out the jets wouldn't fix .

[Good Cheer]

Once used my 16 ounce Dr. Pepper for a fire extinguisher on a Holley.
Said you're welcome, got back on the bicycle and rode away. :)

[rbuck351]

Hollys are a pain when a high lift long duration cam is installed. The engine drops vacuum at idle and you need a handful of different numbered power valves to keep the power valve from opening at idle. Keep replacing power valves until you get one that stays closed at idle and still opens at the right time.

Readjusting the throttle cable/cables on the early 750 four was just another part of a tune up as well as matching the dual points and adjusting the valves, timing and matching the carbs idle speed and idle air mix. Older bikes have more issues as the main metering rods, the slides or the throttle shafts/holes wear. It's all about what you have to replace and what you can get by without replacing. Replacing 4 carbs on a 750 four would probably cost as much as one Harley carb. You couldn't get China knock offs at the time.

Being able to properly rebuild and adjust a carb used to make a guy real popular. Now few people even know what a carb is and a whole lot fewer know how they work.

I would bet good carb cleaner would fix your Harley carb unless it has a lot of miles and worn throttle shafts and bores. If the Harley carb has any plastic or rubber parts in it, do not put them in B 12. Also don't buy any of the cheap stuff. The B12 will probably cost around $30 to $35 for a one gallon can that is about half full of chemical with water on top to keep it from evaporating. Do not stick any part of you hands in or on any bit of the chemical.

[Gator 45/70]

I like carburetors, Clean most of the insides with Pam, Eats the tarnish off post haste

[JonB_in_Glencoe]

I like Carburetors.
BUT, I hate tuning/tweaking Carburetors.

[gwpercle]

It isn't the carb. you dislike it's the junky Chinese copy you bought for 70 bucks .
I'm still driving a 1968 Chevelle ...any part from China is JUNK ... It is amazing that they sell parts that don't work out the box . Not one chinese part I have ever bought was any good ...all trash .
The chinese will be the end of the old car hobby , they flood this country with electrical parts that are designed not to work and made of substandard materials .
Buy american car parts if you can find them ... I know your pain !
Want decent replacement ...Edlebrock are the carbs I roll with .
Holley carbs are good but expensive ...I've always had great service with Edelbrock .
Don't try and go cheap on car parts ...you will pay for cheap parts because they don't last . My first cheap carb lasted 3 days ...that taught me a big lesson .
Gary

[~JM~]

As long as the shaft bushings are not leaking, a quality (Made in USA or Japan. Avoid China, Mexico, etc.) rebuild kit & a can of Berryman's is what you need.

https://www.berrymanproducts.com/products/eco-friendly-products/berryman-chem-dip-carburetor-and-parts-cleaner/

PS. Wear eye protection & gloves.

PPS. Try to locate a source of ethanol free Premium gas. If not available in your area, buy some Lucas Ethanol Treatment & Seafoam:
https://lucasoil.com/products/fuel-treatments/safeguard-ethanol-fuel-conditioner-with-stabilizers
https://seafoamworks.com/product/sea-foam-motor-treatment-oil-fuel-additive/
I have been using both products in my small engines & haven't had to rebuild a carb since.

[Mk42gunner]

Other than the small engine carbs from the last twenty years that don't like cheap(???) gas, the worst one I have ever messed with is the Zenith carburetor that was on my WD. From what I can gather they had to be on the verge of flooding to run right, and every one I saw on a running tractor was like that.

I solved my problem by replacing it with a Marvel-Schebler (also correct for an Allis Chalmers WD). I took three of them apart on my tailgate and made one, maybe two that work.

The new nanny state Holley's don't seem nearly as good as the ones that you could tweek and get right.

Truth is I think everyone is spoiled by the lack of maintenance required with fuel injection in vehicles.

Robert

[Froogal]

I have rebuilt carburetors from derelict, abandoned, fence row farm tractors. Very seldom did I encounter one that could not be made good as new, and when I did, it was usually because someone who should not be allowed to own mechanic tools had been there first. Carburetors are NOT simple. In fact they are quite complex, but if you take the time to understand just exactly how it works, and functions, it can be easy to rebuild.

[gwpercle]

As long as the shaft bushings are not leaking, a quality (Made in USA or Japan. Avoid China, Mexico, etc.) rebuild kit & a can of Berryman's is what you need.

https://www.berrymanproducts.com/products/eco-friendly-products/berryman-chem-dip-carburetor-and-parts-cleaner/

PS. Wear eye protection & gloves.

I'm happier than a clam at high tide with a rebuilt part from Mexico ...there's a 50/50 chance it will work . I ordered three starters ( to test before install ) to get one that worked and it came from Mexico ! The other two came from China and failed the test out the box .
Gary

[Harter66]

Carburetors are simple , air sucks through a choke point , siphoning fuel out of a same level basin/reservoir . When there's more air moving through the choke point siphoning happens faster . That rate is controlled by making the suck hole bigger or smaller .

Getting 2,3,8 or more to work together in sync or series and timed linkages paired with fixed adjusting fuel metering is where it gets complicated .

They're still simpler than that down stream fuel rail regulator that throws codes for 6 other things . I mean there's either fuel in it or there ain't and if it is there there's only too much not enough or close enough to run .

Sure never having to remember this is no choke slow 3 pump car not the 1 pump full choke truck is nice and all but I've been chasing an low speed studder for 6 months that codes as a bank 2 misfire ....... No kidding I wouldn't have guessed , how's about a hint fuel,fire,or compression ? Oh right , why didn't I think to change the left rear turn light ....... Psych ! Get some line drier it rained all week and you know I just suck up water like a sponge in the desert ........

[David2011]

I can work on carburetors. Computer controlled fuel injection is harder. LOTS harder.

[megasupermagnum]

I can work on carburetors. Computer controlled fuel injection is harder. LOTS harder.

No, it's more expensive. You don't need anything but a couple wrenches and screwdrivers to work on a carb, but it takes the patience of a saint to work on, jet, and adjust one. It takes years of experience to get good at it.

On the other hand, fuel injection is expensive. Automotive is standardized since 1996, but anything else usually requires its own software, and it isn't cheap. But once you have that, working on fuel injection is cake.

[megasupermagnum]

Carburetors are simple , air sucks through a choke point , siphoning fuel out of a same level basin/reservoir . When there's more air moving through the choke point siphoning happens faster . That rate is controlled by making the suck hole bigger or smaller .

Getting 2,3,8 or more to work together in sync or series and timed linkages paired with fixed adjusting fuel metering is where it gets complicated .

They're still simpler than that down stream fuel rail regulator that throws codes for 6 other things . I mean there's either fuel in it or there ain't and if it is there there's only too much not enough or close enough to run .

Sure never having to remember this is no choke slow 3 pump car not the 1 pump full choke truck is nice and all but I've been chasing an low speed studder for 6 months that codes as a bank 2 misfire ....... No kidding I wouldn't have guessed , how's about a hint fuel,fire,or compression ? Oh right , why didn't I think to change the left rear turn light ....... Psych ! Get some line drier it rained all week and you know I just suck up water like a sponge in the desert ........

Carburetors do not suck or siphon. Some designs even pressurize the fuel bowl. While a lot of time jetting involves changing fuel jets, just as often you run into air jets. A smaller air jet will richen the mixture. then you throw all kinds of different stuff into the mix like accelerator pumps, metering rods, needles, and anything else people have come up with to smooth out the translon from idle to full throttle. I don't hate carburetors, but they aren't simple at all. Say you have a slight lean bog. You could put a bigger pilot jet in, and find you just made the problem worse because what you really need is a bigger squirter. You could also be running lean in the middle, so you raise the needle, but now it's fat on the bottom, so you put in a smaller pilot, and now it's lean at 1/4 throttle. Now you repeat with a whole different needle. Then the temperatures changes 40 degrees and you either do it all again, or just live with it.

No, just no. I don't hate carburetors, but they aren't simple. Not in design, or operation.

[uscra112]

No, carburetors aren't simple. They are essentially fluidic computers, with nearly a century of engineering behind them.

But consider: I bought my current ride, a 1976 BMW R75/7 which has over $2000 in delicious performance goodies on it, for $700 from a computer nerd who couldn't get it to run above an idle, because he hadn't the savvy to clean the mainjets. Used only the tools in the onboard tool kit, and the diagnostic computer in my head, which doesn't need power from the grid to run. Has no sensors (oxygen, coolant temp, air temp, manifold pressure, und-und-und) to go sour and disable the system on an Interstate in central Kansas, requiring a 100 mile tow and a three-day wait for the replacement part to be shipped in, as happened to someone I know of who was riding a modern fuel-injected BMW to Colorado a couple of summers ago.

Thinking about "lean bog" reminds me of how we solved driveability problems with Honda 550 fours in the '70s by throwing away the customers' aftermarket velocity stacks and putting the factory air filter box back on. I've never been entirely sure, but I still think those Keihins were tuned to take resonances in the airbox into account. I once helped a guy pick up a good 6 tenths of a second at a dragstrip with that trick.

[rbuck351]

Carburetors are anything but simple. The very early ones were simple but they were missing many of the things that make a smooth transition from idle to wide open. I work on my BILs antique cars. They are Schacht cars and have a carb that has no idle system at all but have a spring loaded device that changes the venturi size with out side vs inside air pressure and is adjustable via a spring tension screw. I have yet to find any info on the proper way to adjust these carbs. That plus the fact that they are 100+ years old and worn makes for fun adjusting. Anyway these simple carbs are much harder to tune than one that has places and things to adjust.

[uscra112]

That sounds like the vacuum slide carbs on my Beemer. Or the SUs that so many British cars in the '50s and '60s had. The diaphragms in my Bings are the Achilles Heel of the design. Why I carried spares on the bike any time I was going to be traveling any distance from home. Been threatening to swap in a set of Mikunis, but have never done it.

[Harter66]

I disagree but I spent most of my time with Stromberg , Marvel ,and Bendix updraft singles to run 200 CID 60 HP O4 up to 235 HP 540 CID with remote mixture adjustment . No doubt a pressure carb is more tool intensive but it really doesn't matter whether it's for 185 hp 470 cid 0-6 or a 2000 hp R27 north of 4000 cid through a wet blower or with a super charger over a blower on a Rolls Royce 1700 cid V12 pushing 5 atmospheres they are a simple device . They just meter fuel via a choke point that draws liquid fuel into the air stream and makes it an explosive/extremely fast controlled burn mixture .

The same thing happens in a Carter AFB , ThermoQuad , Rochester Quadrajet , or a FoMoCo spread bore 4v , 2v , or a primary/secondary Isuzu 2V .

I don't know how one would describe the air flow , whether by force or by draw via causing a low pressure area , drawing fuel into the air stream other than a siphon . While that's not true of a pressure carburator that is really closer to a continuous flow TBI than a true carburetor . Also a pressure carburator doesn't care if it's upside down or sideways or has centrifugal loads as long as it has 5 psi of liquid fuel , depending on its exact form , it does it's job and has since 1935 or so .

I also hate air bleed jets vs fuel bleed jets the adjustment is backwards and I screw it up at least twice .

What do you call the rush of air moving through a venturi from 29.92 inhg to 15 inhg ? I mean if you cover the hole the air is passing through it'll pull your hand and anything else that gets into the flow right down into it just like a vacuum cleaner and if a shop vac doesn't suck I don't know what it does on the intake side .

[uscra112]

Any one interested in fuel delivery to high horsepower engines needs this book:

https://www.amazon.com/gp/product/1911658506/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

A coffee-table size book and not cheap, but it's a deep, deep dive into all the problems faced by the British and Germans trying to get power and reasonable life out of their V-12 fighter engines during WW2.

[rbuck351]

A vacuum doesn't pull anything, the high pressure side pushes your hand or anything else that gets in the way to the low pressure side. A vacuum cleaners inside low pressure allows high pressure outside air to flow in. Std air pressure at sea level is about 14 psi. When you evacuate the air from the inside of a vacuum cleaner via a fan you create a lower pressure inside. Then if their is a hole between the inside and the outside the higher outside pressure will rush to the lower pressure inside.

With a carb there is a venturi ( air flow restricter). When a piston is pumping air out of a cylinder it creates low pressure on the downstream of the air flow through the venturi and very low pressure when the throttle plate is closed. The float bowl/gas chamber is vented to the out side air. Outside high pressure air pushes the fuel to the low pressure side of the venturi. Vacuums do not pull. Siphoning is a method of getting liquid to flow by creating a low pressure on the down stream side of a siphon tube via some type of pump.

The choke point on a normal carb is not the only point they mix /meter fuel.Most have a second Vinturi above the throttle plate that is the delivery point of the main fuel discharge and the idle fuel delivery is at the edge of a closed throttle plate.
Most motorcycle carbs don't use a throttle plate so the carb bore is closed by a round slide.The idle delivery point is in the down stream side of the venturi and the main delivery point is at about the beginning of the venturi.
The slide gradually increases fuel flow in three steps. First is right off idle where the air/fuel flow is controlled by an angled cut on the back of the slide. The angle of the cut can increase or decrease the air/fuel delivery but is fixed from the factory and has to be recut to change it. A proper cut will keep it from bogging as the throttle is opened (no accelerator pump).
Next is the main metering tube and rod. The main metering tube is not normally modified as the adjustment is with the rod. It is tapered and increases fuel flow as it is lifted out of the main metering tube as the slide is lifted. This rod usually has 5 notches with a c clip that can be moved to increase or lower the rod in the main metering tube. Raising increases fuel flow. Much of the above idle fuel is adjusted via this rod.
Last is the main jet which only comes into play at wide open throttle unless it is way to small to handle all the fuel needed by the main metering tube and rod. It screws into the bottom (intake) of the main metering tube and controls the maximum fuel flow at wide open.

And one more small thing. Float level which changes fuel air mix throughout the entire throttle range.

So yeah if you understand all this and how to determine what is what by listening to the exhaust tone, then carbs just dump some fuel and air together to get about a 13/1 air /fuel mix. (Simple,nothing to them.) Sorry, don't know how to use purple.

[VariableRecall]

I have a little bit of experience with a Carburetor vehicle. Used an older Jeep Cherokee for a whole season in Eastern WA. Now I understand why "letting the car warm up" was a thing back then! When things got cold boy did the engine get cranky! Despite having an automatic transmission, I've stalled the poor thing on more than one occasion due to not warming it up enough. My dad helped me adjust the idle speed of the engine to prevent it from stalling when it had stopped. It now idles high at about 800-900rpm but it's a lot better than throwing it in park and cranking the engine again for a couple of stops.

Using a carbureted vehicle is quite a different experience! It reminds me of using a trolling motor, as it feels like you have direct control over the engine (outside of the gears of course). That also means, you are subject to the errors that even the most simple fuel injected system doesn't have to worry about.

If anything, I am quite thankful that fuel injection has become so prolific and efficient, because there are some things that are best left to electronics and machines, and for efficiency's sake, let's leave the pedal feathering to the big dumb machine.

[uscra112]

The choke on that Cherokee wasn't working right, or if it had a manual choke, you weren't working it right.

[megasupermagnum]

The choke on that Cherokee wasn't working right, or if it had a manual choke, you weren't working it right.

Maybe it was different when they were new, being I was born after carburetors were already gone from cars, but I have NEVER found a car with a working automatic choke. Putting in a cable for a manual choke was pretty much the standard, but you still don't just get in and drive away.

[VariableRecall]

The choke on that Cherokee wasn't working right, or if it had a manual choke, you weren't working it right.

Well, at the time I wasn't doing it right. I didn't give the machine enough time to warm up. Leaving it like that makes it much easier for the engine to putter out if you slack on the pressure on the gas. After 10 minutes or so, the issue never really happens.

[Gator 45/70]

Well, at the time I wasn't doing it right. I didn't give the machine enough time to warm up. Leaving it like that makes it much easier for the engine to putter out if you slack on the pressure on the gas. After 10 minutes or so, the issue never really happens.

Those old gasoline engines won't develop full HP until its 180 degrees or better, That's why a cold engine falls on its heehaw

[john.k]

If you can drive away straight after starting ,then the carb is either flooding,or too rich ..(in the daytime here,not 40 below!).....when I had trucks ,a ten minute warmup ,and the carb adjusted for a slight lean misfire at idle would save a tankfull of gas a week..........When emission controll standards came out,a lean idle actually produced unburned hydrocarbon emissions ,and idle mix had to be set richer ,to eliminate the misfire.

[beemer]

I had a friend that would rebuild carburetors on his kitchen table for a twelve pack of Bud.
I gladly brought him beer with the side draft SU units from a Volvo that I had. He was delighted to get something different to work on.
RIP, Borrego!

Sent from my SM-A716U using Tapatalk

I used to rebuild my old Beemer carbs on the kitchen table. The bike sat in the living room. My neighbor said that was nasty, I said "Nope, that's the cleanest place in the house". I did live alone at the time.

I owned two BMW R90"s, a 1974 and a 1976, the '74 for over 32 years. I set the carbs with a rig made from a strip of plywood, 20 ft. of clear tubbing and a little MMO, low tech and effective.

Sold them last spring as I don't feel comfortable riding anymore but do miss it.

[rbuck351]

There are two types of auto chokes. One has an electric heater coil close to a bimetal strip coil. When cold you push the throttle once to allow the choke to close. You then start the engine and as soon as it starts a vacuum unloader opens the choke a specific amount, usually about 3/32". Also the heater coil starts to warm up and causes the bimetal strip coil to start unwinding and slowly opens the choke. The other has a copper tube that pulls heat from the exhaust manifold to warm the bimetal coil doing the same as the electric heater coil. These tubes tend to plug and don't supply heat. Either one works fine until something plugs or the coils gum up if they are adjuster properly and kept clean.

[375RUGER]

Sometimes on a new carb or a fresh rebuild when you get a leak like that you have to tap the body a few times to "free" the float so it will operate properly.

[Tazman1602]

I can work on carburetors. Computer controlled fuel injection is harder. LOTS harder.

Totally agree, I must be old because carbs are easy. Float level, float drop,
proper seals proper tune no problem, tri-power, dual quads, no problem. I guess I’m a dinosaur but that’s ok….

Art

[Froogal]

Totally agree, I must be old because carbs are easy. Float level, float drop,
proper seals proper tune no problem, tri-power, dual quads, no problem. I guess I’m a dinosaur but that’s ok….

Art

You and me both. I despise all of this modern, electronic stuff.

[Messy bear]

Rbuck351 gave good explanations on carb theory and operation

[downzero]

You and me both. I despise all of this modern, electronic stuff.

Once you figure it out, it's far superior. Even my '80s truck with EFI is awesome compared to any carb, but it still has to be timed right, have good plugs in it, etc., or it'll run like crap just the same.

[rbuck351]

Fuel injection does work better than a carb. Most electronic fuel injector systems can check fuel mixture and readjust it to proper air/fuel ratio about 60 time a second. Carbs for a lot of reasons can't do this. If a carb gives me trouble while driving, I can pull over and usually be able make it go again. When an electronic fuel injection system quits, normally your done and it gets expensive.

[uscra112]

Superior until it goes bad and the computer to make it run again at all costs $250. At a breaker - don't even ask what Chrysler wanted for a new one,

[Idaho45guy]

Rode my Harley to work yesterday afternoon. Got off work at 11 pm and 37 degrees out. Started the bike and was letting it warm up when the throttle cable broke. 15 miles from home. Got a ride to my house from a beautiful girl I used to work with and then grabbed some tools and drove back to work. Ended up swapping the throttle cable with the idle return cable and was able to drive home by twisting the throttle forward to accelerate.

[Tripplebeards]

I was the service manger for a Harley Davidson shop for four years. From 2000 to 2004. Ordered my fatboy the year before I went to work for them. Pay was extremely poor but it was the place to work if you like to work with and look at hotties all day long. I had several meetings right at the main plant in Milwaukee on updates. Around a good 3 to 4 a year on updates. The year 2000’ was the first year Harley offered fuel injection or carbureted bikes. My techs had the toughest times figuring out how to tune the fuel injection bikes at the time. What a pain! Just like everything new. There was always a “flat spot” somewhere along the acceleration path. Harley never had the kinks worked out of their upgraded powder tuners back then. The aftermarket power turners were even worse. You had to put the exact specified aftermarket or upgraded Harley components in the bike listed. If not the power tuners would have a “lag” or “flat spot” some where along the acceleration process. Anyways, of the carbs of your and my years just need the fuel bowls taken off. Then remove the main jet ( or both jets) and spray carb clean through both to make sure the jet holes are clean and not plugged. Also where it screws into the bottom of the carb. I haven’t driven my Fatboy for 10 years and prior to that about 5 times a year on average after the frost couple of years I bought it new. I did what I described above last summer and it popped right off. Runs like new again after 15 minutes. Mine is 2000’ BTW. Last time I looked it might have rolled over 12k. I put on 6k my frost two years and it didn’t get a lot of use after that. I started out with a new 600f2 Honda. Frost year they came out. The next year traded it for the first 900RR year produced in 1993. I then traded for another new one the next 3 years after that. Picked up 2 YSRs along the way and a RSXR750 used for lottery nothing. Figured it was time to grow up and buy a Harley. I still love the chrome yellow bike but it just doesn’t get me exited to to ride it like the crotch rockets so it sits. Won’t get rod of it since it’s paid off and I won’t ever buy another. At the price of gas I will be pulling it out this year. IMO carburetors are very easy to work on. They just need to be cleaned most times. Start messing with the adjustments is where you’ll run into problems.

[David2011]

No, it's more expensive. You don't need anything but a couple wrenches and screwdrivers to work on a carb, but it takes the patience of a saint to work on, jet, and adjust one. It takes years of experience to get good at it.

On the other hand, fuel injection is expensive. Automotive is standardized since 1996, but anything else usually requires its own software, and it isn't cheap. But once you have that, working on fuel injection is cake.


Totally agree, I must be old because carbs are easy. Float level, float drop,
proper seals proper tune no problem, tri-power, dual quads, no problem. I guess I’m a dinosaur but that’s ok….

Art

I got my first street rod in 1972 when almost everything had carburetors and the standard street rod carb was a Holley or two or three. I made a mistake with it one day and it ran super rich when I went for a quick drive after dark. I pulled over and adjusted the float level with only a street light in the distance. Adjusted the jetting by the exhaust pipe color. I loved small block Chevies and Holley carbs! I didn’t know it was supposed to be hard so I just did it.

[uscra112]

A crude exhaust gas temperature gauge, such as is found on almost all piston aircraft engines.