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Matt, Engineer
Category: Small Engine
Satisfied Customers: 21607
Experience:  Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
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2006 Deere 757 25HP Kawasaki 650 hrs. I'm stumped. Has been

Customer Question

2006 John Deere 757 25HP Kawasaki 650 hrs. I'm stumped. Has been sitting for years due to loss of compression. last week I re-seated valve seals and installed new head gaskets. Ran great for 1 day of commercial mowing. Power-washed and lost spark. New Coils and plugs started right up and ran for an hour until parked. Right now I have to hand choke the motor to start. Runs flawlessly but cannot start on its own. I have cleaned the carb, replaced batt., tested fuel shut-off valve, inspected air cleaner. Cylinder compression looks good, Cleaned and dried all connections, bright blue spark, gap between coil and mag set. Any Ideas?
Submitted: 11 months ago.
Category: Small Engine
Expert:  Matt replied 11 months ago.


have you tried removing the air cleaner and seeing if it'll start up without it?

as its possible that water has gotten into the air cleaner and swollen the filter?

If this is OK then I'd check that auto choke mechanism on the carb is functioning correctly

Customer: replied 11 months ago.
I am hand choking without the filter installed. then re-assembling the filter while running, which is dry and perfectly clean. There is no auto choke feature. The manual choke is functioning correctly.
Expert:  Matt replied 11 months ago.


OK this sounds like the fuel passage / jetting isn't getting enough air

there's a air mixture jet and gallery that sounds like it may be blocked up so preventing air being drawn over hte main jet

so when you hand choke it you throttle the air flow enough to generate a larger vacuum than normal and start pulling enough air over the main jet and so drawing fuel

so I'd check the main venturi in the carb and its air passages are clear which are usually fed with a jet that needs clearing out