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Low power after tune-up

#1

M

mjw357

I have an Exmark zero-turn with Kawasaki FX801V engine. Brought it in the garage last fall, all was running perfectly. This winter I changed the oil and filter, fuel filter and the rocker cover gaskets because they were leaking a bit. While I had those off I figured I would check/set the valve clearance.


Went to mow this afternoon, started right up and let warm for a couple minutes before I started.


Wheeled over to the yard, half throttle, turned on PTO to start blades, full throttle. Seemed OK for a few seconds then lost power when I started moving. It just is not making full power/RPM’s with mower engaged.


What’s everyones first thought?


#2

B

bertsmobile1

Double check those valve clearances.
good chance one has opened up & pushrod fallen off .


#3

Scrubcadet10

Scrubcadet10

Start it up and pull a spark plug wire off of a cylinder, one at a time. If it dies completely with one plug wire off, the other cylinder is dead,probably due to what bert said above.


#4

T

txmowman

mjw357 said:
I have an Exmark zero-turn with Kawasaki FX801V engine. Brought it in the garage last fall, all was running perfectly. This winter I changed the oil and filter, fuel filter and the rocker cover gaskets because they were leaking a bit. While I had those off I figured I would check/set the valve clearance.


Went to mow this afternoon, started right up and let warm for a couple minutes before I started.


Wheeled over to the yard, half throttle, turned on PTO to start blades, full throttle. Seemed OK for a few seconds then lost power when I started moving. It just is not making full power/RPM’s with mower engaged.


What’s everyones first thought?
Click to expand...
What did you set the valve lash to? Did you perform the adjustment properly?


#5

7394

7394

I'm leaning to valve lash set too tight.


#6

B

bertsmobile1

Scrubcadet10 said:
Start it up and pull a spark plug wire off of a cylinder, one at a time. If it dies completely with one plug wire off, the other cylinder is dead,probably due to what bert said above.
Click to expand...
I would be inclined to check the pushrods first as that is easy & cheap, if you used a gasket .
However those thin steel pushrods tend to vanish into the engine at the drop of a hat and then it becomes a big expensive job


#7

M

mjw357

Each cylinder brought to TDC,
txmowman said:
What did you set the valve lash to? Did you perform the adjustment properly?
Click to expand...
Each cylinder brought to TDC, valve clearance set to 0.002" per manual found online. That sounded a bit tight to me, I thought it would be more like 0.004"-0.006".


#8

Tiger Small Engine

Tiger Small Engine

mjw357 said:
Each cylinder brought to TDC,

Each cylinder brought to TDC, valve clearance set to 0.002" per manual found online. That sounded a bit tight to me, I thought it would be more like 0.004"-0.006".
Click to expand...
Start mower and let warm up briefly. Spray water on each exhaust pipe and watch how it vaporizes. Pull the valve cover(s) accordingly and inspect. Something going on with the valves most likely.


#9

T

txmowman

The service spec is .004” - .006”


#10

M

MParr

Valve lash is too tight.


#11

7394

7394

mjw357 said:
Each cylinder brought to TDC,

Each cylinder brought to TDC, valve clearance set to 0.002" per manual found online. That sounded a bit tight to me, I thought it would be more like 0.004"-0.006".
Click to expand...
That is definitely TOO tight. That online spec is NOT correct. I spoke to a Kawasaki Tech on my previous Kaw engine about this specifically ...
True spec is .004 - .006. Re-adjust to intakes @ .004 or .005 & Exhausts @ .005 or .006


#12

M

mjw357

UPDATE: opened up the rocker covers and found this.
All parts there, I must have nut tightened everything down. Set intake to 0.004 exhaust to 0.005 an closed it back up. See how it runs tomorrow.
Thanks everyone for the replies and info.

Attachments







#13

M

MParr

Did you inspect the pushrod?


#14

S

SeniorCitizen

A Infrared temperature gun will check exhaust pipe temperature if you have one .


#15

M

mjw357

MParr said:
Did you inspect the pushrod?
Click to expand...
Yes it is straight, no marks.


#16

M

mjw357

Got it out, started right up, ran great for couple minutes mowing then suddenly died. Restarted with choke, same thing mowed for a minute and died. Repeated that a couple time, then ran it aound the yard full throttle and then noticed it was surging. So thinking under the load of mowing it’s dying. Dirty carb?


#17

7394

7394

How long did you run it with valve lash TOO tight ? Hope it's not a burnt valve.


#18

M

MParr

mjw357 said:
Got it out, started right up, ran great for couple minutes mowing then suddenly died. Restarted with choke, same thing mowed for a minute and died. Repeated that a couple time, then ran it aound the yard full throttle and then noticed it was surging. So thinking under the load of mowing it’s dying. Dirty carb?
Click to expand...
You may have some internal damage. You will probably have to remove the head and have a look.


#19

M

mjw357

Update 3: the solution to the surging/dying was in the carburetor. This is the passage opposite the needle valve. That little square piece of debris must have been the culprit. Sprayed it out and re-assembled all is good. Wife is out mowing right now. She loves to mow!

Attachments





#20

woodstover

woodstover

www.engine-specs.net

Kawasaki FX801V (852 cc, 26.6/25.5 HP) vertical V-Twin engine: review and specs

Kawasaki FX801V (852 cc, 26.6/25.5 HP) V-Twin vertical engine specifications: horsepower and torque, cylinder compression, valve clearance, oil type and capacity
www.engine-specs.net www.engine-specs.net
1710709729650.png


#21

woodstover

woodstover

7394 said:
That is definitely TOO tight. That online spec is NOT correct. I spoke to a Kawasaki Tech on my previous Kaw engine about this specifically ...
True spec is .004 - .006. Re-adjust to intakes @ .004 or .005 & Exhausts @ .005 or .006
Click to expand...
Make sure engine is cold when adjusting valves


#22

7394

7394

mjw357 said:
Update 3: the solution to the surging/dying was in the carburetor. This is the passage opposite the needle valve. That little square piece of debris must have been the culprit. Sprayed it out and re-assembled all is good. Wife is out mowing right now. She loves to mow!
Click to expand...
Happy days are here again.. (y)


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