Small Engines (Lawn Mowers, etc.)/JD rx-75 Riding mower


QUESTION: Good day sir,
  I have a John Deere RX-75 riding mower with 9hp Kawasaki motor. Ran fine until last week.
Starts up fine but now after a couple minutes starts to run slowly, almost stalling, and creates thick giant clouds of white smoke!!
The motor will slow down, lots of white  smoke comes out the exhaust.  It will speed up and the smoke clears. It will then repeat this cycle over and over every 10 seconds or so. It stalls at lower speeds but will run at half to full throttle, but always with the white smoke continuously cycling.
  Could you please offer some troubleshooting tips? Thank you.

ANSWER: Is the oil level too full?

Is the oil runny and smell like gasoline?

When was the last time the oil was changed?

What weight oil was used to re-fill the engine after the oil change?

Let me know.


---------- FOLLOW-UP ----------

QUESTION: oil level is normal.
oil does not smell of gasoline
oil was changed last year
30w oil was installed
Thank you

ANSWER: Go the the website below and download the service manual for your engine model.

Take a look at the trouble shooting section along with the engine compression spec.  Check the engine compression and see if it is within compression spec listed in the engine service manual.

Let me know the compression.


---------- FOLLOW-UP ----------

QUESTION: compression checked within spec., engine ran fine last week. problem started this week. revs up and down, on down rev, almost stalling, smoke starts pouring out of the exhaust, it recovers, runs a few seconds, and does the white smoke cycle again. it will do this all day if I let it run.
Thank you

The up and down revving is most likely caused by a dirty carburetor.

Have you removed, dis-assembled and cleaned the carburetor with compressed air from an air compressor and spray can carburetor cleaner?

Make sure to check any insulators and gaskets that may be between the carburetor and engine block.  These will sometime warp causing a very small air leak but even a small air leak will cause the engine to rev up and down.


Small Engines (Lawn Mowers, etc.)

All Answers

Answers by Expert:

Ask Experts


Eric A. Jones


Lawnmower Repair . Certified Master Service Technician from B&S. Have 23 years experience on B&S, Lawn Chief, Weed Eater, Echo, Peerless, Wheel Horse, Snapper, Atlas, MTD, McCulloch, Homelite and many other numerous brands. Specialize in electrical repair.


Born and raised in the midwest. Started tinkering with engines when I was about 14 on my Suzuki RM-80. I began lawn mower repair at a small hardware store. I knew absolutely nothing. I read lots of repair manuals and met an older fellow who taught me many lessons. I continued working on small engines through high school and paid my way through college working on mowers at the same hardware store. Decided to get away from the midwest and mower repair so I joined the Air Force. I repaired air traffic control electronic equipment and ended up in Hawaii where I got a part time job at Small Engine Clinic. I gained a lot of experience from the Small Engine Clinic and had a blast repairing small engines. I then took the Briggs and Stratton Master Service Technician test and earned my MST. I then traveled to Wisconsin where I attended the factory update training seminar and received formal training. Continued working on mowers part time as I completed 20 years of military. Retired from the military on a Friday and continued in the lawn and garden industry the next Monday.

MAS Aerospace Operations BA Mathematics AAS Electronic Communications AAS Electronic Technology

©2016 All rights reserved.