# Carb Cleaning & Disassembly Tips/Tools



## Bob Driver (Nov 1, 2017)

I posted the thread Instant Small Engine Carburetor Expert, so I thought I would share a thread with a few tips you could use along with the technical details on disassembly (already posted) on how to clean carburetors. Most Old School guys like me will tell you they hate modern ethanol fuel. I felt that way for a long time, but then my wallet told me this stuff generates about ½ of the “fun coupons” he hides from the wife for me in the Spring.

Kohler and Briggs both will tell you ethanol fuel has a “shelf life” of about 60 days in a fuel system. After that, it starts to turn to something resembling Vaseline. Let it sit long enough and it turns into shellac as it evaporates. The tiny passages in carb jets don’t like either one. So how do you go about cleaning a carb that’s been sitting for 6 months, or longer?

Most DIY guys use spray carb cleaner and compressed air, if they have it. I sometimes clean 4-5 carburetors a day in the Spring. If I used that much spray cleaner… 1) It would be really expensive 2) I’d be higher than Tommy Chong from the fumes. I broke down and bought an Ultrasonic Cleaner years ago and use Purple Power for the solution. Ultrasonic cleaners can be really expensive, but they are the ultimate for cleaning carbs. Harbor Freight sells one; it’s the usual HF quality/durability for the price. If you’re considering a higher end ultrasonic cleaner … Look for one with heat, buy the biggest capacity you can afford, and the more transducers the better. The thing that always goes out on them is the Chinese electronic motherboard. Here’s the one I’ve used for the last 5 years. Note that it’s “mechanical” and not electronic. Either control unit is replaceable for about $40. On most electronic units, a replacement Chinese motherboard is usually more than ½ the price of the machine. Mine is a 12L (3 gallons) commercial unit and runs about $350 now, but it’s big enough to do two carbs at once when I need and it’s what actually prints the $$$ for my buddy the wallet to hide in the Spring…










If that’s not your price point, try using what I started out with… “A poor boy carb bath”. You could run out and buy a gallon of Gunk and they’ll throw in a nice big can/basket for $23. Commercial Gunk is really harsh on o-rings/seals/plastic parts, your hands/nose, and some aluminum carburetors really don’t like it if you have to soak them for a long time and will turn an odd color of gray. As mentioned, that nasty brown stuff in the carb is a form of shellac. What can you use to thin/dissolve shellac? That’s right… Lacquer thinner. Nothing dissolves shellac faster than lacquer thinner. The problem with lacquer thinner is that it evaporates really fast if it sits out in an open container. I use “A poor boy carb bath” to presoak the bodies/bowls before they go in the tiny bubble maker machine to save changing fluid so often. You can use it to do an "overnight soak". It’s much easier to work with than that gallon of commercial Gunk, does a better job, and without risking damaging the rubber/plastic carb parts. I buy a gallon of lacquer thinner at HD for $17 and keep it in a wide-mouthed 1 gallon glass jar with a rubber sealed lid. We do like our sweet tea here in MS, so I was able to buy the jar at a yard sale for $3.... I got to be careful with it around some of my customers, it's a clear liquid when it's fresh and will form bubbles if you shake it. One of my ******* customers wanted to taste test it, mistaking it for another popular beverage we sometimes make in these parts....










Now we get down to taking the carb apart. Got to get those damn cheap Phillips bowl screws out without stripping them…. 1) Rest the carb carefully upside down on a wooden block. 2) Insert a Phillips head (I use a drywall screw bit) and give it a good whack with a ball peen hammer while holding it firmly. Works 90% of the time to "shock" the threads loose before you try to take them out with a regular phillips screwdriver. If not, apply a *LITTLE* heat on the thread bores (I just use a BIC cigarette lighter) and repeat until it comes apart. If you do strip the threads 1) Use a blunt-ended metal drift 2) Place it over the stripped out Phillips hex squarely 3) Whack it with the hammer until you see the “cross on a plate”. 4) Insert the drywall bit and whack it to re-form the Phillips hex. Sometimes that screw just won’t give it up. Time to break out the left-handed #8 Irwin (5/16") nut extractor over the entire screw head…










Now you got to get those brass jets out of that narrow jet tower without damaging the them. It’s almost guaranteed that the only slotted screwdriver you have that will actually fit down in the jet tower does not have a blade width that will fit the brass slot tight enough to not strip it. That’s where you need a set of “Jet Screwdrivers”. Two sizes.... Briggs part #19061 (small - for idle jets), Briggs part # 19602 (big - for main jets). About $10 each










Once the jets/mixing tower are out and soaked in a spray can lid with lacquer thinner, you've got to make sure every tiny hole is clear in the main jet, emulsion tube, and slow jet. Don't forget that on some carbs with those big threaded *brass* (usually not if they're steel) single bowl screws,* the bowl screw is the main jet* and has passages from the threaded area to the center of the screw that have to be open. I use a welding tip cleaner to carefully probe each passage clear and a 20X jewelers eye loupe to see what the hell I'm doing. Once I've probed all those tiny holes in the sides and both ends of the jets/emulsion tube is where I use the spray carb cleaner. Index finger plugging the business end of the jet, pinch the slot end between your middle finger and thumb, can of carb cleaner (with the little red straw) in the slotted end tapered hole. Use the carb cleaner spray pressure to test that every opening is completely clear(especially in the emulsion tube) and sprays the same nice stream... About $10 total for both tools
















Pay attention when you take out the float needle. If it's got a metal tip, it may have a little tiny 0-ring in the seat (not sold separately, only in a O/H kit). Blowing down through the fuel inlet with compressed air, or even spray carb cleaner, will make that little tiny O-ring land in Alabama, or Arkansas, depending on which direction I'm facing. Always blow from the seat side and then just enough to make sure it's clear. Check with the loupe to see that the little red 0-ring is still there before you hang the float.

Once I get the carb back together, I vacuum test the float seal *BEFORE* I install it. I use either a Mighty Mite, or a Stens carb tester (Part #705-020). Turn the carb *upside* down and apply -5" of vacuum on the fuel inlet port for 30 seconds. If it holds that vacuum, the float needle is seating, and it's not going to PO you by leaking fuel all over the place and make you pull the carb off again. Turn the carb over with the *bowl down* and the vacuum should drop off instantly. If it doesn't, the float/needle is hanging up in the seat. $40 for either tool seems like a lot, until you have to pull the carb off a v-twin for the 2nd time because the needle is leaking off, or the float/needle is hanging up... If you don't want to buy the tools, you can use a clean piece of fuel line (or dirty if you just happen to like the taste of gasoline) like a straw, but it's not going to pick up a slow leak from a bad float needle. Float bowl facing up - no flow. Float bowl down- flow

















Please forgive me for my longwinded post, but hopefully I’m passing along some useful information, to someone, that took me years to learn… Hey -- the information is free and you’re the one that clicked on it


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## thepumpguysc (Jan 25, 2015)

Good stuff there Bob.. & thanks for the tips..


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