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Kawasaki FD750D-AS04 running poorly

#1

ILENGINE

ILENGINE

I have this engine on a Scag that is runnng poorly. New NGK BPR2ES plugs. Been through the carb. Adjusted valves to factory spec. Compression on both cylnders is around 110. Will not start hot or cold without choke. Popping back through the intake intermittent on both carb barrels. Throttle shaft and linkage holes are worn and the carb and some of the intake gaskets are either hard to find or NLA.

If you apply almost full choke will smooth out and the rpm's increase greatly. But if you spray brake cleaner or dribble gas into the intake immediately goes rich. And engine will not idle and engine doesn't surge. Check spark on both cylinders using 2 different spark checkers, and spark doesn't appear to be dropping out.

And the engine has 1800 hours according to the hour meter on the Scag.


#2

T

txmowman

First of all, it is normal to have to choke an engine, even hot, with a carburetor that has a fuel solenoid. Has this engine ever had any valve maintenance? Meaning, cleaning the valves, reaming the guides, decarboning, etc.


#3

ILENGINE

ILENGINE

txmowman said:
First of all, it is normal to have to choke an engine, even hot, with a carburetor that has a fuel solenoid. Has this engine ever had any valve maintenance? Meaning, cleaning the valves, reaming the guides, decarboning, etc.
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I am going to say NO, but truely unknown. I am thinking in the back of my mind this a valve issue also, but without pulling the exhaust and the intake and draining the cooling system to pull the heads to examine the valves won't be able to prove it.


#4

StarTech

StarTech

Hmmm, No problem getting the gaskets from RBI. The 11060-2468 and 11060-2469 both are in stock as is the carb side gasket.

As the throttle holes if you referring to the carb body, resize and add bushings. Bushings will have to be made custom but they are no problem to make. Now the throttle shaft would have to replaced due to wear. I have done several Nikki twin barrel JD ZTRs and save those $600+ carbs.

As to which linkage holes you didn't say which but those items has to be replaced, or welded up and re-drilled. Usually the linkage rods would be worn too.


#5

T

txmowman

The carburetor shaft being worn would likely cause enough of an air leak for the need to apply full choke to enrichen the air/fuel mixture.


#6

Scrubcadet10

Scrubcadet10

Have you sprayed carb cleaner directly on the throttle shaft to verify it is or isnt pulling air in from there?


#7

A

Auto Doc's

ILENGINE said:
I have this engine on a Scag that is runnng poorly. New NGK BPR2ES plugs. Been through the carb. Adjusted valves to factory spec. Compression on both cylnders is around 110. Will not start hot or cold without choke. Popping back through the intake intermittent on both carb barrels. Throttle shaft and linkage holes are worn and the carb and some of the intake gaskets are either hard to find or NLA.

If you apply almost full choke will smooth out and the rpm's increase greatly. But if you spray brake cleaner or dribble gas into the intake immediately goes rich. And engine will not idle and engine doesn't surge. Check spark on both cylinders using 2 different spark checkers, and spark doesn't appear to be dropping out.

And the engine has 1800 hours according to the hour meter on the Scag.
Click to expand...
Your description favors a very worn cam.

Gummed up main jets are also a real issue if it only runs with choke,

The fuel anti backfire valve will also produce similar results when it is not working. Full choke will pull fuel past the shutoff and allow it to run as a "get it in the shop" measure. Shutoff solenoids do gum up and get sticky or quit working.


#8

ILENGINE

ILENGINE

Scrubcadet10 said:
Have you sprayed carb cleaner directly on the throttle shaft to verify it is or isnt pulling air in from there?
Click to expand...
I have and with no change. So I don't think leaking that much air around the shaft. Leakdown testing shows less than 15% bypass at TDC so at least top of stroke the rings, head gasket and valves are sealed.


#9

ILENGINE

ILENGINE

Auto Doc's said:
Your description favors a very worn cam.
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It is in the back of my mind. I don't remember any of the valves short stroking like the lobe is worn but I need to pull the valve covers back off and make sure they are not short duration. Meaning the lift is normal but the valve open time could be shortened if the lobe has narrowed due to wear.

At full throttle it sounds almost normal. But below 1/2 throttle is gets uneven and almost sounds like one cylinder is dropping out but I don't think it is just one cylinder I think both are dropping out.


#10

A

Auto Doc's

ILENGINE said:
It is in the back of my mind. I don't remember any of the valves short stroking like the lobe is worn but I need to pull the valve covers back off and make sure they are not short duration. Meaning the lift is normal but the valve open time could be shortened if the lobe has narrowed due to wear.

At full throttle it sounds almost normal. But below 1/2 throttle is gets uneven and almost sounds like one cylinder is dropping out but I don't think it is just one cylinder I think both are dropping out.
Click to expand...
read my upadate


#11

ILENGINE

ILENGINE

Auto Doc's said:
Your description favors a very worn cam.

Gummed up main jets are also a real issue if it only runs with choke,

The fuel anti backfire valve will also produce similar results when it is not working. Full choke will pull fuel past the shutoff and allow it to run as a "get it in the shop" measure. Shutoff solenoids do gum up and get sticky or quit working.
Click to expand...
I have removed the main jets and have both sprayed them out and also cleaned any old residue out with a wooden toothpick. And the fuel solenoid has been both operated by hand to make sure it wasn't sticking and also bench tested to make sure it is retracting. It seems to run relatively good at fuel throttle without choke. The choke in only needed when starting and also trying to get it to idle.


#12

StarTech

StarTech

ILENGINE said:
I have and with no change. So I don't think leaking that much air around the shaft. Leakdown testing shows less than 15% bypass at TDC so at least top of stroke the rings, head gasket and valves are sealed.
Click to expand...
This why you to the modified leak down test on OHV engines so you can all of the stroke. Can't be done on L-heads but quite easily done on OHV engine. Taper and oval is more pronounce at the middle and bottom of the stroke.

I had several years ago a Tecumseh horizontal that was giving running problems when I cam with the modified test and found the lower part of the stroke badly worn out.


#13

A

Auto Doc's

ILENGINE said:
I have removed the main jets and have both sprayed them out and also cleaned any old residue out with a wooden toothpick. And the fuel solenoid has been both operated by hand to make sure it wasn't sticking and also bench tested to make sure it is retracting. It seems to run relatively good at fuel throttle without choke. The choke in only needed when starting and also trying to get it to idle.
Click to expand...
Hello ILENGINE,

Does this carburetor have the top plate on it with 3 screws? If so....

The carburetor can usually stay mounted, perform the following:

Remove the top plate and gasket carefully. You will see the right and left channels and some very tiny holes. Use a very fine strand of wire such as an instrument tenor string or a single wire pulled from a wire hand brush to clean the small holes out. Do not try to jamb anything soft into the holes. Clean out with carb spray lightly.

Then put the gasket and plate back in place and snug the screws down. Don't overtighten the screws.

Those very tiny holes are the idle bleed air passages.

Hope this helps you.


#14

ILENGINE

ILENGINE

Auto Doc's said:
Hello ILENGINE,

Does this carburetor have the top plate on it with 3 screws? If so....

The carburetor can usually stay mounted, perform the following:

Remove the top plate and gasket carefully. You will see the right and left channels and some very tiny holes. Use a very fine strand of wire such as an instrument tenor string or a single wire pulled from a wire hand brush to clean the small holes out. Do not try to jamb anything soft into the holes. Clean out with carb spray lightly.but may

Then put the gasket and plate back in place and snug the screws down. Don't overtighten the screws.

Those very tiny holes are the idle bleed air passages.

Hope this helps you.
Click to expand...
This carb has a 2 screw cover that covers a cavity that basically acts like the fuel bowl vent. It has separate air bleed screws that can be accessed from outside the carb. I have blown carb cleaner through the air bleed but may go back and recheck with running wire through the air bleed holes.

Also when I get a chance may pull the rockers to do another leakdown test.


#15

ILENGINE

ILENGINE

Update. It appears that there are sources that have the compression for this engine incorrect. The source I came across say compression was supposed to be 107. But that is a misprint and is actually supposed to be 170. Gentleman we have a compression problem.


#16

S

slomo

ILENGINE said:
New NGK BPR2ES plugs.
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Hope that is the OEM plug number. That number 2 in the part number is a rather hot plug.


#17

ILENGINE

ILENGINE

slomo said:
Hope that is the OEM plug number. That number 2 in the part number is a rather hot plug.
Click to expand...
It is.


#18

A

Auto Doc's

ILENGINE said:
It is.
Click to expand...
lawnmowerpartstore.com

Spark Plug for Kawasaki FD501V FD671D FD711D FD750D 920702110 BPR2ES 92070-2110

Spark Plug for Kawasaki FD501V FD671D FD711D FD750D 920702110 BPR2ES 92070-2110
lawnmowerpartstore.com lawnmowerpartstore.com


#19

A

Auto Doc's

ILENGINE said:
Update. It appears that there are sources that have the compression for this engine incorrect. The source I came across say compression was supposed to be 107. But that is a misprint and is actually supposed to be 170. Gentleman we have a compression problem.
Click to expand...
Hello ILENGINE,

I looked on Parts tree and it shows the cam along with a small return spring, so my assessment is that this cam has a compression release. 107 PSI cranking compression is actually decent compared to others I have seen.

Not sure how or if 170 PSI can be achieved with a compression relief camshaft design.


#20

ILENGINE

ILENGINE

Auto Doc's said:
Hello ILENGINE,

I looked on Parts tree and it shows the cam along with a small return spring, so my assessment is that this cam has a compression release. 107 PSI cranking compression is actually decent compared to others I have seen.

Not sure how or if 170 PSI can be achieved with a compression relief camshaft design.
Click to expand...
Straight from the FD750D service manual

Compression Measurement
• Before measuring compression, do the following.
􀀀 Be sure the battery is fully charged.
􀀀 Thoroughly warm up the engine so that engine oil between the piston
and cylinder wall will help seal compression as it does during normal
running.
􀀀 Stop the engine.
• Disconnect the spark plug caps of each cylinder and remove the spark
plugs.
• Attach the compression gauge assembly firmly into one plug hole.
Special Tool - Compression Gauge: 57001–221 [A]
Compression Gauge Adapter: 57001–1159
• Ground the spark plugs to the engine.
To avoid fire, do not ground the spark plugs in closed positions
to the plug holes. Keep the plugs as far away as possible from
the plug holes.
• Using the starter motor, turn the engine over with the throttle fully open
until the compression gauge stops rising; the compression reading
obtainable.
• Repeat the measurement to the other cylinder.
Cylinder Compression (MIN): 1171 kPa (170 psi)


#21

A

Auto Doc's

Maybe they did not have the throttle wide open (high) and choke fully open? Need to retest to verify. For both cylinders to be low would be unusual.


#22

ILENGINE

ILENGINE

Auto Doc there is no way of knowing how long this engine has been acting up. Maybe it hasn't been running correctly for several years. And what I have been reading makes it sound like sudden low compression and loss of power and shutting down is more common that you would think. Several people that tore down the engine reported stuck rings. And this engine has symptoms of being an oil burner. #1 cylinder shows signs of oil burning on the plug I took out with oily residue on top of both pistons when examined with a borescope.

I also have a Kawasaki Mule 3010 with the FD620D that is showing similar issues at the shop. If I get a chance tomorrow will rerun compression on the 750 and check compression on the 620


#23

A

Auto Doc's

ILENGINE said:
Auto Doc there is no way of knowing how long this engine has been acting up. Maybe it hasn't been running correctly for several years. And what I have been reading makes it sound like sudden low compression and loss of power and shutting down is more common that you would think. Several people that tore down the engine reported stuck rings. And this engine has symptoms of being an oil burner. #1 cylinder shows signs of oil burning on the plug I took out with oily residue on top of both pistons when examined with a borescope.

I also have a Kawasaki Mule 3010 with the FD620D that is showing similar issues at the shop. If I get a chance tomorrow will rerun compression on the 750 and check compression on the 620
Click to expand...

ILENGINE said:
Hello ILENGINE: For Horizontal shaft engines, I use a 50/50 mix of ATF and Acetone, put the pistons at about the halfway point, pour in the mixture and reinstall the plugs finger tight. Let the mixture creep in for about a day, then remove the plugs a purge the cylinder by cranking the engine. From there check the oil level, because it will likely be high. Change the oil and filter then install the plugs and fire it up. I have freed up a lot of carbon stuck rings in horizontal shaft engines using this method. Vertical shaft engines are a little more difficult and it takes a couple of times with the mixture while jacking the mower up high on the engine end to get as much saturation in the cylinder(s) as possible.
Click to expand...




#24

ILENGINE

ILENGINE

ILENGINE said:
I also have a Kawasaki Mule 3010 with the FD620D that is showing similar issues at the shop. If I get a chance tomorrow will rerun compression on the 750 and check compression on the 620
Click to expand...
Checked compression on both the 750 and the 620 The 750 is reading 125-130 on both cylinders hot. For comparison the 620 is reading 170 on #1 and 220 on #2. The Mule is having intermittent issues with the valve in the electric fuel pump which didn't act up the day I was doing the initial testing on the no start issue.


#25

A

Auto Doc's

Hello ILENGINE,

I know you are trying to cover two machines with similar engines, but let's take one at a time to keep things direct and simple. Adding in variables from other machines just creates confusion.

What seems similar is not when it comes to this stuff.


#26

Its Me

Its Me

remove the valve covers check to see if the push roads are seated in the cam area in the block.


#27

O

outdoorpowermike

Ok, from what you say the carb needs to removed and cleaned the correct way, with a ultrasonic cleaner, I use it every time with lean running carbs. Fixes 95% of the time with new intake gaskets. Or just replace carb with new carb. Some times cleaner can't fix it. Really never had any problems with amazon carbs. After market stuff works 99% of the time and not a lot of cash, like under $50.00 maybe. I guess it is a 2 bbr carb? One side of carb is clogged. But spray around intake manifold by cyl heads and see if rpm changes.


#28

ILENGINE

ILENGINE

outdoorpowermike said:
I guess it is a 2 bbr carb? One side of carb is clogged. But spray around intake manifold by cyl heads and see if rpm changes.
Click to expand...
Spraying around intake manifold gaskets does nothing. Spraying into the carb causing a rich run. I have since discovered posting this that the fuel pump is bleeding off, so I am questioning fuel flow. Have a new pump ordered and will see what happens.


#29

ILENGINE

ILENGINE

outdoorpowermike said:
Ok, from what you say the carb needs to removed and cleaned the correct way, with a ultrasonic cleaner, I use it every time with lean running carbs. Fixes 95% of the time with new intake gaskets. Or just replace carb with new carb. Some times cleaner can't fix it.
Click to expand...
This thing has already been through the 2.3 gallon 6 transducer ultrasonic cleaner for 2 30 minute cycles, plus had all the passages ran with a thin wire and blown out with both carb cleaner and compressed air. And my experience with Amazon carbs has been not great. All have tended to fail within 30 minutes for various reasons. I order Amazon carbs just to steal the parts off of. Like the accelerator pump for a Kohler Command engine. Or the fuel bowl and throttle slide for ATV carbs.


#30

O

outdoorpowermike

Did the fuel pump help?


#31

ILENGINE

ILENGINE

outdoorpowermike said:
Did the fuel pump help?
Click to expand...
Shipping delayed. Suppose to be here tomorrow. OEM pump.


#32

S

SeniorCitizen

JD X350 with 180 hrs. running so bad while mowing i didn't think it would make it back to the shop . Pulled original plugs and replaced with what the Auto supplier referenced the NGK to Champion that I ask for . I;ve never had a engine start so fast when the 1st piston went to compression .


#33

ILENGINE

ILENGINE

SeniorCitizen said:
JD X350 with 180 hrs. running so bad while mowing i didn't think it would make it back to the shop . Pulled original plugs and replaced with what the Auto supplier referenced the NGK to Champion that I ask for . I;ve never had a engine start so fast when the 1st piston went to compression .
Click to expand...
The last 3 Kawasaki engines that I tried Champion plugs in wouldn't start hot. I won't touch another Champion if I can avoid them.


#34

A

Auto Doc's

For most V-twin applications I use Champion RN12YC or RN14YC and have not had issues with them in years.

The ones I do not like just have the word "Torch" printed on them. They have ruined a few coils especially on push mowers.

With Stihl 2-stroke engines I get the best performance out of NGK plugs.


#35

O

outdoorpowermike

Did you replace fuel pump yet? If so what was the outcome?


#36

ILENGINE

ILENGINE

outdoorpowermike said:
Did you replace fuel pump yet? If so what was the outcome?
Click to expand...
Fuel pump replaced but no change in running. I am going to try to swap the carb when it gets here Monday and see what happens. I did test the pump I took off and it wouldn't hold pressure


#37

ILENGINE

ILENGINE

ILENGINE said:
Fuel pump replaced but no change in running. I am going to try to swap the carb when it gets here Monday and see what happens. I did test the pump I took off and it wouldn't hold pressure
Click to expand...
Got the Amazon carb installed, which is not my desired choice, due to quality control in most cases, but anyway the new carb allowed the engine to fire up and run smooth from full throttle down to an idle, which would never idle before, and will even fire back up without the choke applied. So there is definitely something goofy about the carb.


#38

A

Auto Doc's

Hello ILENGINE,

I've had pretty good luck with aftermarket clone carburetors in recent years. A lot of original ones are no longer available. I have had better results with Ebay then I have Amazon though.

Some OE carburetors get blocked air bleed passages over time that no amount of cleaning will correct. Along with that, the throttle shafts wear out the housings, especially in sandy/dusty conditions. Any stray air beyond the choke plate or before the venturi and a carburetor will not meter the fuel correctly for the engine to run properly.

Glad to hear you got it running well.


#39

S

slomo

ILENGINE said:
Got the Amazon carb installed, which is not my desired choice,
Click to expand...
Yup yup.

I found not to buy the cheapest knock off carb listed on fleabay for example. Say the cheapest listing is 25 bucks. I get the 35 dollar one. Had good luck doing this.

Used to get the cheapest listing. Had several problems that I corrected myself.


#40

O

outdoorpowermike

Nice to read that your running again.


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