Late Fathers PT-422: What should I do with it?

[3rd Coast]

New machines have Kohler engines. Power trac sells the parts to swap a 25 hp Robin to a 25 hp Kohler, so they probably have kits for the 22 hp machines too. They are pretty easy to swap out. It is a night and day difference between the Robin and the Kohler. The 25 hp Robin is no longer made. Don't know about the 22 hp.

Here are the Kohler engine spec numbers I have used as a direct bolt on replacement for the 25 hp Robin: CH 730-3208 CH730-3207 and CH740-3363

Some other spec numbers that may work (call Kohler to confirm 866-465-6453) are CH730-3004 CH730-3331(key start on engine) AND CH750-3006

You will have to check with Power Trac and or Kohler to see if any of these are options for your PT 422

That is super helpful, thank you!

 

[3rd Coast]

Spoke with Terry and he confirmed the CH7303004. Looks like its another carb'ed engine? Is there a cross to a FI motor? I will ask him when I call back, he'd like a 5 digit serial off the tractor to confirm parts needed for the swap.

Jacks Small Engine looks like a decent price, any other recommendations?

 

[airbiscuit]

Do you want to re-power it because it isn't running well?

 

[3rd Coast]

Do you want to re-power it because it isn't running well?

If it comes to that, yes. Right now it's running pretty good so I'm not so concerned but want to be prepared in the future when I am ready to repower.

 

[airbiscuit]

Keep using ethanol free gas and 1oz Seafoam per gallon, and things will be good.

 

[3rd Coast]

Keep using ethanol free gas and 1oz Seafoam per gallon, and things will be good.

I ran the tank empty, filled with rec gas and 10oz seafoam. Ran great for over an hour yesterday. Today it started fine, ran great for 2 minutes. Then the back firing started again. Eventually it stopped backfiring but the motor sounded like it was running really rich and down on power. I turned the rpms all the way up and you could almost hear the motor start to lean out and eventually sounded right and ran great again. I'd really like to nip this backfiring in the bud. Can you still get carbs for these?

 

[airbiscuit]

I don't know much about Power Tracs, but here are the options I would consider

• Call Terry at Power Trac, and get his advice
• Find the engine model number and look up Robin Carburetors on Amazon, Ebay, Google (lots listed)
• Take it to a reputable small engine mechanic and have then diagnose/fix it - it is just a small engine after all.

 

[3rd Coast]

Well I think i found the cause, I believe the coil on the right cylinder is shorting.

Any advice on removing the engine front cover to access? How deep is a coil replacement repair? Gas tank out? Front hydraulic pump removed?

 

[airbiscuit]

Wow. You are making progress.

 

[3rd Coast]

Wow. You are making progress.

I've been running ragged trying to diagnose this thing. I've tried 3 different plugs. Cleaned carb countless times. Best I can figure is all the messing around finally caused it to fail permanently. It now will only idle. Any throttle and it will backfire.

I put an inline tester on the left plug and pulled the boot off the right plug. Fired up and ran great(for one cylinder) through all Rev ranges. Strong ignition through the tester.

Then I did the reverse and put the tester on the right plug and pulled the boot off the left. Idled fine but as soon as I turned up the throttle it started backfiring and there were gaps in ignition cycle through the tester.

Happy to be moving in the right direction but this looks like a daunting task to swap out the coil.