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Carburetor troubleshooting How do I set the correct level of petrol in the chamber without any instruments (needle and seat level)

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The manual will tell you float height in mm so just use a Steel rule.

Posted on Apr 25, 2013


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Posted on Jan 02, 2017

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SOURCE: Problematic carburetor on 400cc Kawasaki

I'll need some more information. Does the bike start at all? Does it idle fine, but then dies if you give it gas? Try to explain in detail what is going on so I can help you with this. There are a few things to check for, start by making sure your gas is good DON'T USE ANY GAS WITH ETHANOL (corn stuff) and that it is new. Another thing is to make sure you are getting spark. A simple way is to take the spark plug out while keeping it in the wire and touching it to the outside of the engine (grounding it), turn the motor over and you should see spark. If not, thats something you will need to correct. You don't have a year or what type of motorcycle so I'm assuming its a late 70's, early 80's KZ400 you are talking about. If so, the points could be the culprit as well (if the spark isn't going). But for the most part, the "needle" settings will only help with it's ability to rev high (main jet) and if it dies at idle, your idle jet is plugged up. Get back to us on the specifics and I can help more.


Here is a great site if it IS a KZ400

Posted on Nov 08, 2010

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1996 750 katana suzuki how to set floats?

- Now days some carburetors are produced which are fixed and no adjustment is provided.The float is made up of whole plastic like material.
Some floats have the copper/metal notch for the adjustment of fuel level.
- Take the carburetor assembly out.
- Remove the fuel bowls.
- Place the carburetor assembly with the floats upward towards yourself.
- Float level gauge and active data list (taken from the workshop manual) is required to carry out the adjustment. But you can simply adjust the float level correctly without any gauge.
- Hold the carburetor assembly at your eye level in such a way that the carburetor No. 1 is in front of you. Behind is No. 2 carburetor, then behind is No. 3 and then the No. 4. Or we can say that the carburetor No. 1 hides the carburetors 2, 3, and 4.
- Examine carefully the floats of all the individual carburetors be parallel to the surface of the carburetor where the float bowl face is seated and tightened.
- Adjust the float level by bending the float notch towards the needle valve (to decrease the float level and to raise the float) or away from the needle valve to increase the float level (to lower the float).

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What the cause of the carborador is always over flow of gas??

The float height in the bowl is set to high or the needle and seat is not closing correctly.

Feb 01, 2015 | Cars & Trucks

1 Answer

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Okay,as far as I can remember this model is simple valve petrol as all dirt bikes without additional vacuum hose, right.
If it is on the left-hand tank I is the tap tap fuel.
From there to the carburetor is one hose for fuel supply and the nozzle is the height of the carburetor to the gate chamber.
All other outlets are the carburetor.

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1 Answer

S&S motor with CV carburetor; Start and run idle great but have problem with aceleration . Carburetor cleaning, aceleration pumps is good, gas is ok.

Hi Dennis, if you have a carburator the usual suspects are:
1. Damaged or restricted fuel tank venting system (gas cap).
2. Inlet system air leak.
3. Vacuum piston malfunction.
4. Accelerator pump leaking or no output.
5. Plugged bowl vent.
6. Fuel level (float chamber) too low.
7. Restriccted fuel supply passages.
8. Plugged jets or passages.
9. Worn or damaged needle or needle jet.
10. Enrichner valve not seated or leaking.
Good luck

Btw, I’m available to help over the phone in case u need at

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1 Answer

Havingproblemwithassembly of carburetorrebuiltkit

Hi Pathernis, You have forgotten to mention which vehicle you're working on and consequently I'm giving you broad instructions for working on carbs. Please note that if distortion has occurred between the throttle body, (the part with the butterfly's and throttle linkages) and the float chamber, a flat spot will occur during acceleration. The most usual cause of this damage is the removal of a carburetor from an engine that has not cooled sufficiently. If you are asking about the needle and seat assembly (and I'm not sure you are) the seat fits into the top housing of the carburetor assembly. It is fitted with a gasket washer (usually copper or aluminium) between it and the housing. It should be screwed in firmly with a large screw driver or by using a socket (tube) spanner if manufactured with the required faces. The needle will then be fitted into the seat and followed by the float. One of the most important settings on the carburetor is the float level adjustment, so make sure you get it correct. If it is too tight, either there will be no fuel or too little going into the float chamber, if it is too loose, flooding will result. The other needles are for mixture control which basically control the idle. For carburetors with single choke there will be one for double or multiple chokes, the primary chokes (the smaller) will have one each. Fit the springs onto the screws so that they are between the body of the carb and rest on the shoulder of the screw. Screw the mixture control screws in lightly until contact is made, but do not force further. When fitted and tightened, unscrew three and a half turns. Before fitting fitting the top housing (usually referred to as the trumpet), fit the replacement gasket and pour into the float chamber enough fuel to fill one third, which will obviously raise as the float attached to the trumpet is lowered into the chamber. (Some carbs have the float fitted into the chamber and not to the trumpet) Fit all hold down screws before tightening any, making sure the lengths are correct before fitting. Once all screws are fitted, tighten from the centre where the carburetor is narrowest, working outwards in a spiral pattern. When fully assembled re-fit to the intake manifold using new gasket. Final tuning of mixture idle control is carried out after confirming ignition timing is correct. Hope this is of some help.Regards John

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1 Answer

Carby is flooding

If the carburetor is flooding it is the needle and seat under the float in the float chamber that is either stuck, leaking (a bit of dirt caught in the seat) or the float level has changed or the float is leaking. Any one of these faults is cause for removing the top cover of the float chamber to investigate and repair the problem. (A crack in the housing cannot be ruled out although unlikely).

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1 Answer

Its running to rich ?

I believe those adjustments are air jets, so closing them off run too rich. Also open the slotted plugs on the float bowl to check the fuel level, adjust by running the needle and seat assembly out or into the float chamber to achieve the correct level- it quits ******* fuel when it's right. Next -(if that hasn/t helped) Look up the jets and adjustments for that engine application.

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What is the float setting for a 1990 tw200 Yamaha. How do you know when to replace needle and seat

Hi, the fuel level should be 0-2mm below the float chamber mating surface.

Replacement of needle set is needed, when the needle is visibly worn/damaged, or you have problem with its functions ( for example, having fuel in air filter-when needle not close correctly).

Btw, when replacing the set, it is useful to slightly chamfer the innet perimeter of the seat- it can scratch the needle.

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Poulin p3314 gas runs out carb

Set the H and L jet screws CW to stops (lightly), then CCW 1-3/4 turns each. This is a basic setting and both need to be turned CW somewhat when the engine runs. Recheck the lower chamber in the carburetor for correct installation of the needle, seat, spring, fulcrum, and diaphragm. Go to: for a detailed look at Walbro brand carburetors. Even if you do not have a Walbro carburetor, the principles are much the same. Make sure the fuel tank vent is open.

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What is the float height setting for a 1984 harley davidson ironhead sportster with stock carburetor

With the float bowl off and the float assembled in the carb, hold the carb on it's side with the needle and seat hinge upwards.

Set the float height to 0.630" to 0.670" (16-17mm) from the "bottom" of the float to the gasket surface where the float bowl gasket seal is.

These carbs are notorious for leaking past the needle and seat even when the float level is set correctly. They make a tool for refurbishing the seat in the carb as it is not replacable but the tool is very expensive for what it is and the amount of use will get out of it ($100). Sometimes I've set the float level an additional 1mm low (18mm) to put more pressure on the needle if it does leak. Good Luck!

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