20 Most Recent kawasaki Fh641v 21hp 21 Hp Riding Lawn Mower Engine () - Page 3 Questions & Answers

might be time for a good carb cleaning

take it apart and clean the jets

do you have dirt floating around in the carb?

When it begins to stall, loosen the gas cap. If performance improves, clear the gas cap vent holes.

Gary

You have a problem with your carburator.The problem is most likely the float, the needle valve ,or the needle valve seat. This isn't a difficult fix, you need to remove the fuel bowl under the carburator which is held in place buy a 1/2 inch bolt. There you will see your float, gently push up the float, it should be parallel with the upper section of the carburator. If not adjust float to make this happen. If float is off this is your problem, also float should not be full of gas, if so replace. If not we move on to the needle valve, remove pin that holds up your float and inspect your needle valve tip , if damaged replace. This could be your second problem,if not we move on to the third problem.The needle valve sits in a seat, it is about 1/4 inch round with a 1/32 inch hole in the center, top is flat, bottom is grooved. This seat can be removed with a pick tool. This problem can be fixed with carburator on the engine, but most of the time carburators are removed. You can do what ever you wish.
I believe the problem is with your float adjustment , you can fix this quick and get mowing again.
I am interested in how you make out. GOOD LUCK.

hi there garn8

you will want to use a 10w/30 synthetic blend oil 4 cycle engine oil api service CJ-4

this synthetic blend gives good protection as recommended by kawasaki

use will most likly need about 2 litres + a oil filter

you will need your model and type codes from engine sticker ie fh641v-as04

here is web site

http://kmcb2c.econnect.partsandwarranty.com/kmcb2c/Menu?action=CATALOGB2B&chID=319529&elementType=1&historyDepth=1&CHANGENUMBEROFITEMS=63

then you need to select eg as04 or ????? from the list

cheers pauly46

A quick explination of how to tell how big a Kawi is the model number. Those ending in 0 are the rough displacement (cc's) of the engine, those ending in 1 are a up or down hp version of the 0's in the same family. A quick explination of how to tell how big a Kawi is the model number. Those ending in 0 are the rough displacement (cc's) of the engine, those ending in 1 are a up or down hp version of the 0's in the same family. A quick explination of how to tell how big a Kawi is the model number. Those ending in 0 are the rough displacement (cc's) of the engine, those ending in 1 are a up or down hp version of the 0's in the same family. all aa





check your engine model #
all fh641v series 675 cc 21 hp

Specs: HP cc Bore x Stroke

FH480V 16HP 472cc 68mm x 65mm
FH541V 17HP 585cc 74mm x 68mm
FH580V 19HP 585cc 74mm x 68mm
FH641V 21HP 675cc 75.2mm x 76mm
FH680V 23HP 675cc 75.2mm x 76mm
FH721V 25HP 675cc 75.2mm x 76mm

FH641V 21HP 675cc 75.2mm x 76mm 41.19 cubic inch

there must be differences in the valves and carb sizing / jetting to make engines put out more hp similar to briggs with their engines

When asked for serial, I.E. AS01, BS01, etc., the lower the letter, the newer the engine. It doesn't really matter, except for maybe spark plug reach or other subtle changes

A quick explination of how to tell how big a Kawi is the model number. Those ending in 0 are the rough displacement (cc's) of the engine, those ending in 1 are a up or down hp version of the 0's in the same family.

here is good website for any parts -:
http://www.ereplacementparts.com/kawasaki-fh641vas04-stroke-engine-parts-c-30157_30211_32002.html

cheers pauly46

Symptoms are caused by the engine running lean. Clean the fuel system including blowing out all jets in the carby. Regards Phil

hi david

need more info , your description says that engine will run without ht leads being connected to plugs ?

most times if plugs are connected and key turned off , engine will run on then eventually stop and can sometimes even reverse its rotation when it does so which is known dieseling or run on

if the plug leads are off and the engine continues to run the only way it may run is if it has carbon glowing on the piston top or cylinder combustion chamber

Ignition Theory of Operation

Mounted to the periphery of a flywheel are a pair of magnetic poles (south leading in clockwise rotation), generated by

a permanent magnet. By rotating the flywheel (magnetic poles) clockwise past the ignition module on a laminated core group, a voltage is generated in the primary winding (L1).

This generates a small bias current to flow through the control resistor (R1) to the base of (Q1). This base drive causes

the transistor to conduct (turns on) completing the primary circuit. Current flows from the high side of the primary winding

through the transistor (collector to emitter) to ground.

The trigger sensor (TS1) senses the optimum time (peak current) to remove the base drive from the transistor (Q1).

This abrupt "turning off" of the transistor causes an interruption in current flow which allows its associated flux collapse,

and several hundred volts is induced through the primary winding (L1) inducing a very large voltage in the secondary

winding (L2).

When the secondary voltage reaches several thousand volts the spark plug (SP) gap is ionized and ignition

occurs. The placement of the trigger sensor internal to the ignition insures constant timing over speed and temperature

and prevents counterclockwise operation.

The diode (D1) in the ignition shut off circuit blocks inadvertent application of battery voltage, protecting the internal

components of the ignition. With the stop switch (SW) in the closed position primary voltage is routed to ground, preventing ignition operation.

has anyone had the wiring connectors apart in / and around ignition and charging systems?

this problems is very strange

please get back to me

cheers pauly46

Seems odd that after changing carbs you have this symptom but a dirty air cleaner or restiction in the air intake ducting can cause this. I note you said you changed the air filter(s). I am assuming you changed both the paper and foam filters. My thoughts are maybe there is some gasket material partially blocking the intake under the carb so when under load it is acting like the Choke is on. ( Before you go lifting off the carb.. a partially engaged choke valve will do the same thing. It will run just fine at low speeds or little load but when you put a heavy load it will choke out / get too much fuel.

Last thing that can cause the engine to act really weird is that the gas cap is vented and if the vent is clogged in the gas cap it will cause very unstable operation of the engine at higher rpms.

Your engine service manual is here:
http://www.smallenginewarehouse.com/images/manuals/FH641-Service.pdf
Carb informationis in section 2 - 8

I reommend you inspect
- the tank cap (no plastic bag in place of the rubber under the gas cap to prevent the tank from leaking)
- the choke linkage and position of choke valve (Off or partially on?)
- screen if any under the air filter (Thinking out of the box... what if the air filter is being drawn against the air cleaner / filter housing causing a choke situation under load)

Don't do this for very long but try a high load test with the air filters removed.

One last dumb thought is... the fuel pump is ported to the engine crank case breather. If the diaphragm fails it can put fuel in the oil which will cause the oil level to rise due to the added gas and then end up over pressurizing the crank case. (You said you changed the oil.. and I would think the oil level is still the same as it was post oil change.)

Those are my thoughts and recommendations for the moment. If anything else come to mind I will send you another post.

If you have questions feel free to ask. I wll tell you that I am using the service manual and my 40 + years of experience to help you.

Thanks for choosing FixYa,
Kelly

they need to be set a aproximately .008 thous from magnet on flywheel...use plastic feeler gauge or I have used old business card if none available

This sounds like you have a partially clogged idle jet in the carburetor. You can get a rebuild kit from a shop like www.arcolaw for a fair price and install it yourself.
You could also try a product ln.comike seafoam in the fuel to see if it will eat out the gum or debris deposits.
good luck

What is this engine mounted on? If it's on a riding mower, you could have a problem in the interlock wiring that is "killing" the ignition. You can narrow down your search by disconnecting the ground wire that hooks to the ignition coil(s) and see if you have spark after that. If you have spark, then plug the wire back up and see if you lose it again. If you do lose it then you need to start troubleshooting the interlock circuit on the equipment. If you do not have fire with the ignition ground wire disconnected you then need to start looking at the engine ignition system. Hope this gets you in the right direction.

NGK: BPR4ES
CHAMPION: RN14YC

Yes i think you have a weak coil.they cost about 50.00 apiece.