Must-Have Fuel System Info (Why Won't My Kart Start?)

[anderkart]

Here's a video that will help you disassemble and clean your Honda GX200/6.5hp. clone carb, and get a little better understanding how these carburetors function:

http://www.youtube.com/watch?v=q5zbEbq1KX8


The basic way a carburetor works is:

As air is drawn in through your air cleaner and the carbs Venturi, the vacuum that's crated inside the carb siphons/draws fuel (in from the float-bowl), through a very small orifice (hole) in the center of your Main-jet and Emulsion tube, and through the Idle-Jet. This fuel is then simply atomized/blended with the incoming air to make your engine start and run.

(that vacuum of air entering your carb is created by the engines piston going down on its Intake-Stroke)

Its very common for the little orifice's in the Main Jet (and Idle-jet, and Emulsion-tube) to become plugged up with dirt, varnish and rust, resulting in the engine to be difficult to start or not run at all.

The Main Jet (and Emulsion tube/Idle-Jet) can be cleaned by removal and poking them out with a very small piece of wire. And then also following this up with spraying aerosol Carburetor Cleaner (with the straw on the cans nozzle) through all of their tiny orifices.

Be very careful you dont accidentally spray any carb cleaner in your eyes!!! Wear safety glasses for this step!!!)

Here's some pics of (GX200/6.5hp. clone) Main jets and the Emulsion tube:

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Below is an exploded-view diagram of a GX200/6.5hp-clone carburetor:
(the main jet is Item #35 on this diagram below)

Many other brands of 4-cycle go kart engines have carburetor's that are fairly similar to this Honda GX200 design.

#1 - GASKET SET (Honda part# 3477171)

#2 - VALVE SET, FLOAT (Honda part# 1441476)

#3 - FLOAT SET (Honda part# 1441492)

#4 - CHAMBER SET, FLOAT (Honda part# 2455608)

#6 - SCREW SET, PILOT (Honda part# 4219879).

#7 - SCREW SET, DRAIN (Honda Code 1672187)

#9 - SCREW SET (Honda part# 1441518).

#10 - CHOKE SET (Honda part# 1441526).

#11 - CARBURETOR ASSY. (Honda part# 5148093).

#12 - SCREW, THROTTLE STOP (Honda part# 1441559)

#13 - EMULSION-TUBE/NOZZLE, MAIN (Honda part# 4743035)

#14 - GASKET, FUEL STRAINER CUP (Honda Code 0005652)

#15 - INSULATOR, CARBURETOR (Honda part# 4743068)

#16 - GASKET, INSULATOR (Honda part# 3683547)

#17 - SPACER, CARBURETOR (Honda part# 2534055)

#18 - GASKET, CARBURETOR (Honda part# 4725289)

#21 - LEVER, CHOKE (STD) (Honda part# 1440114)

#25 - LEVER, PETCOCK (Honda part# 5140876)

#26 - PLATE, LEVER SETTING (Honda part# 5148135)

#27 - SPRING, PETCOCK LEVER (Honda part# 1807809)

#28 - GASKET, PETCOCK (Honda part# 3440708)

#29 - CUP, FUEL STRAINER (Honda part# 1441583)

#31 - SCREW, PAN (3X6) (Honda part# 0561654)

#34 - PIN, SPRING (2X12) (Honda part# 1441591)

#35 - JET, MAIN (#70) (Honda part# 8832347)




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Its also very common for dirt, rust and varnish to cause major trouble in the carburetors Needle and Seat valve.
Symptoms such as flooding or no fuel in the float bowl will many times be fixed by simply cleaning your needle and seat valve and its related orifices in the carbs main body.

The picture below is a Needle valve: (Its #2 on the illustrated carb diagram above)

The carbs float senses the float-bowl's fuel level, and operates this little valve to either open or closed positions allowing fuel to enter the carb and maintain the correct fuel-level in the float-bowl.

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When your carb is disassembled, try to carefully spray out every single tube, orifice and part of the carb to make sure everything is clean and nothing is still plugged up with dirt, rust or varnish.

If your careful, (and lucky) you can usually re-assemble your carb with the same old gaskets, seals and float bowl O-ring. But not always, sometimes the Float Bowl O-ring becomes hardened or cracked, and it wont ever make a good seal again after being disassembled for cleaning your carb.

If your carbs mounting Gasket falls off, make sure you reinstall it correctly. Its possible to install some upside down where it still fits on, but cant make a seal.

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When we buy gas at a station, it commonly pumps dirt, crap and water/moisture right into our fuel tanks or gas cans.

And then on top of that, lots of karts are either stored outside, or with partially filled tanks in humid conditions where steel fuel tanks (and gas-cans) will rust, thus sending dirt and rust on its way to our nice clean carbs.

Storing your kart (or metal gas can) with either a completely full, or completely empty/well-vented tank will help keep metal fuel tanks from ever rusting in the first place. Because high Humidity levels will cause moisture to condense inside and eventually cause rust.

And If your letting rain somehow get into into your fuel tank or gas can, you deserve all the problems that will result.

So unless there's some type of really good fuel filter used, everyone is just setting themselves up for dirty carb problems to happen over and over and over again !!!

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Dirty carb issues seem to be the most commonly reported problems with Tecumseh specifically, but also all brands of small engines here on DIY.

So I just think everyone needs to be more aware they need to clean and flush their fuel tanks/lines, and also install an additional high quality, In-line fuel filter at the same time the carb is cleaned. (or preferably before problems ever arise...)

I realise some engines like older Briggs have tank mounted carbs, but their tanks can be cleaned/flushed out and fuel strainers can be cleaned/replaced too.

My gas can is plastic and has a very fine-micron screen built into it's spout. And then I also store the gas can, and my kart in the garage with a completely empty fuel tank, lines and carb. I also replace my karts in-line fuel filter often and with the highest quality filter available.

So as a result, I've never once had dirty carb problems with my Tecumseh or any of my other engines.

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Does anyone know if all Tecumseh engines originally came with a factory installed fuel filter or some type of strainer screen?

If they do, It must not work very well... Either that or lots of guys just neglect to replace or clean it out so these dirty carb problems dont just happen all over again.

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Also: simply using a product like Sta-bil:--> http://www.i4at.org/surv/sta-bil.htm
Will help keep your gas from going bad causing you all kinds of similar problems.

Lots of guys just dont seem to realise how fast our modern gasoline can start to go bad nowadays. It doesn't take very long...

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We all just need to be more aware of these issues and help pass the word on to newbies here on DIY

Our slogan could be: Its a whole lot easier to keep it out now, than clean it out later!"

 

[Doc Sprocket]

I agree wholeheartedly!

It's my own personal opinion that the vast majority of carb-related problems are caused by fuel sitting in it for extended periods. I have seen the results- I am currently trying to sort out a quad-carb setup from an Interceptor that had fuel sitting in them for 5-6 years and I can tell you it ain't pretty. When I pulled them off the bike, they were gummed solid- throttle plates, slides, chokes- nothing would budge.

It might be overkill, but EVERY time I park my kart, I shut the fuel valve off and let it idle 'till the carb is dry. I've been running the wee out of it for a few years now, and it starts and runs like a champ- no more than 2 pulls, even at 20*F or colder, no matter how long it's been sitting.

I believe in fuel filters- you can get them at any auto parts store, and cheap. You don't need a high-dollar "performance" goodie here.

I install filters on all my small engines, and anything that didn't come with a fuel valve gets one installed.

I try to run my equipment dry at the end of the season. If I goof up and am left with too much fuel in it- I yank the fuel line off and drain the tank. Failing all else, I'll pour it into my truck and burn it off while it's still good.

None of these solutions really cost anything, and are as close to an insurance policy on your carb that you're going to get. There are never any guarantees, and other things can go wrong, but this takes care of all the common stuff.

Excellent thread, Anderkart, thank you!

 

[karl]

You can buy a cheap Fram fuel for 2 dollars at wal-mart or tractor supply. I got a 3hp briggs with the built in gas tank and it was rusted. 1 minute with the sand-blaster and like new. Also you can shake BBs, nuts and bolts, and anything else you can find in a steel gas tank to clean it. Very good thread anderkart, this should be stickied !

 

[Russ2251]

Additional stuff:
Acetone works wonders on varnished fuel tanks and carb parts.
Avoid exposing plastic/viton/rubber to acetone.

 

[Doc Sprocket]

Makes sense. There's Acetone and Toluene in the spray can of carb cleaner I have, and in the gallon can I picked up for those evil Interceptor carbs is Xylene.

Warning- Rubber gloves, safety goggles, and plenty o' ventilation for all you would-be carb rebuilders out there. These solvents are quite toxic, combustible, skin irritating, and eyesight-removing... Think first- then do.

 

[Bluethunder3320]

that was a not-so-pleasant smell unscrewing the lid to that 8hp briggs that blew up 12 years ago.

yuuucckkkk...........

my clone has a screen thing right under the gas cap that catches anything big. that helps to get one.

also helps to get an in-line filter and clean it out regularly.

 

[bighead]

Boiling the carb bodies and parts in lemon juice is the best way I have found to clean carbs. It works better and faster than carb dip. Only a few bucks a bottle and you can reuse it.

The acid in the lemon juice cleans everything really good. The boiling gets everything.

My carb cleaning kit has a some guitar strings and a jug of lemon juice.

http://cycles.evanfell.com/2008/09/how-to-clean-a-motorcycle-carburetor-the-right-way/

Boiling in Lemon Juice - There is NOTHING BETTER at cleaning carbs than a giant pot of boiling lemon juice. The acidity from the lemons eats through everything; gas varnish, oil build up, dirt, grime, etc. Sometimes I won't even bother doing anything but this - I'll just remove the bowls, remove the caps, then drop everything into the pot and let it sit for 20 minutes (rotate them a few times). The one caveat to doing this is that you'll want to wash the lemon juice off the carbs as soon as you pull them out. So have a bucket of water ready, or a can of WD-40 to hose them down. Also note that the acidity has a tendency to put a dull finish on the aluminum bodies of the carbs. This isn't a problem in most cases, but if you must have everything shiny be prepared to do a little scrubbing and polishing afterwards. It may sound weird, but trust me, I just saved you LOTS of time. (Most dollar stores sell 1/2 gallon jugs of lemon juice, so buying a few gallons will only cost you $6. Plus you can put it back into the bottles afterwards and save it for next time.)

Also if you have to line your tank. Use the POR15 liner kit. Not the Kreem product.

 

[HellSpawn]

that was a not-so-pleasant smell unscrewing the lid to that 8hp briggs that blew up 12 years ago.

yuuucckkkk...........

my clone has a screen thing right under the gas cap that catches anything big. that helps to get one.

also helps to get an in-line filter and clean it out regularly.

Just because the gas you're pouring through that filter is getting cleaned, doesn't mean the tank walls are clean

quality inline filter is best.

 

[anderkart]

Thanks for adding your info guys, keep it coming.

 

[r_chez_08]

Here is a carb check sheet for the gx series engines and clones:
http://www.honda-engines-eu.com/sv/images/59138.pdf

 

[ivickers]

I had a idle problem, found a very fine hair line crack in the insulation block between the carb and head.
renew item.
#15 - INSULATOR, CARBURETOR (Honda part# 4743068)

symptoms;

1. would start with choke,
2. would not idle.
3. would rev okay however with a flat spot off idle
4. would stall off throtle when mobile, eg back off for braking.

 

[r_chez_08]

Is it just me or is it hard to find anywhere to squeeze an inline filter on a clone?

 

[Doc Sprocket]

They can be a little tight. A 90* fitting or two can help in some cases.