Honda 400Ex Carburetor Float Adjustment Full Operating Temp

All made in Taiwan.

Please compare it to what you need to make sure it is the correct kit for you.

Pls provide phone number in the order information, its required for USPS shipping.

Our customer service representative will guide you the returning procedure for replacement.

A brand new replacement unit(s) will be sent to you at our shipping cost.

After we received the returned item, if the item condition is good, we will then make a refund to you.

We reserve the right to refuse refunds or exchanges on items that are returned in unsatisfactory condition.

Please contact us through eBay anytime and we will reply you within 24 hours(weekend excluded).

Please check with customs office of your country to determine what these additional costs will be prior to bidding or buying.

An air screw adjusts how much air is being delivered thru the pilot circuit: in is rich (less air) and out is lean (more air).

This method can also indicate if your pilot jet is too big or too small.

Towards the bottom is an explination about the difference between fuel screws and air screws.

Youll need to be able to access the fuel screw while the engine is running.

FCRs have aftermarket fuel screws that are longer which helps.

On a stock 400EX carb (and many others) I use a 90 degree screwdriver.

If youre lucky, your fuel screw is easily reached with a normal screw driver.

Honda 400Ex Carburetor Float Adjustment Full Operating Temp

On to the procedure 1) Warm up the engine to full operating temp.

Turn up your idle a few hundred RPM using the throttle stop screw (basically you want a fast idle).

Watch for overheating--pointing a big shop fan at your engine will help it from getting too hot during the fast idling.

Each time you change the screw setting 14 or 12 turn or so, wait about 5 seconds to let the idle speed normalize.

Keep going and look for the idle to begin to dropmiss again.

The goal is to find the setting that provides the highest and smoothest idle.

If its unclear exactly were that point is then set to the midpoint between step 3 and step 4.

For example, if the idle starts to drop at 1 turn out and starts to drop at 2 12 turns out then 1 34 of a turn out should be the correct setting.

If the peaksmoothest RPM is reached somewhere between 1-3 turns then your pilot jet is correct (the 1-3 turns applies to most carb types).

If you end up less than 1 turn out then your pilot jet is too big and you need a smaller one.

If you end up more than three turns out or the fuel screw seems to make little difference as you continue turning it out than you need to go up (bigger) on your pilot jet.

If the idle never drops when youre turning the fuel screw out, you need a bigger pilot jet.

Typical fuel screw settings are in the 1 12 to 2 12 range.

Once youve got the fuel screw set, re-adjust your throttle stop screw (idle screw) to an appropriate idle speed.

From here you can experiment with how small adjustments affect low-end (i.e.

The hardest part is usually gaining access to the screw while the engine is running.

Also, you may really have to listen carefully to detect the rpm changes in the idle.

And lastely, a little bit about the difference between fuel screws and air screws: Two stoke carbs normally have air screws and four stroke carbs normally have fuel screws.

You can tell if a carb has an air screw or a fuel screw by its location on the carb.

An air screw will be on the intake side of the carb while a fuel screw will be on the engine side of the carb.