Kawi 25hp V-twin running rough

[mjonesnh]

Mr mojo I have a Kubota that backfires and I don’t like it one bit. I read on here to idle down before cutting it off. Didn’t help tha I could tell. So I’ll try the choke. Thank you sir

Will add that I do idle down also and then pull choke on while turning key off

 

[RandyT]

Have a Kohler Command 23 that was losing power when hot. Had 1 coil going in and out. Replaced both coils and issue disappeared. Engine has always backfired also. Found out if I pull choke on when I am turning key to off that it stops the backfire.

Kohler engines afterfire solenoids only shut off the high speed jet when shut off not the idle circuit which is why Kohler engines are recommended to shut them off at full throttle, to stop fuel being pulled in from the idle circuit

 

[Mike1955]

I give that a try. Mine is more than a backfire it will run backwards it sounds like. And sometimes vapor lock and I have to remove the spark plugs next time I crank it. I’m afraid it’s hottie tear something up. I even added oxtail but it didn’t help. And I have a new 600 dollar carb on it I may start killing it with the blade on

 

[Mike1955]

I give that a try. Mine is more than a backfire it will run backwards it sounds like. And sometimes vapor lock and I have to remove the spark plugs next time I crank it. I’m afraid it’s hottie tear something up. I even added oxtail but it didn’t help. And I have a new 600 dollar carb on it I may start killing it with the blade on

Sorry about the spelling in the previous post I meant to say octain. Spell check got me!

 

[Racer4]

Kohler engines afterfire solenoids only shut off the high speed jet when shut off not the idle circuit which is why Kohler engines are recommended to shut them off at full throttle, to stop fuel being pulled in from the idle circuit

I wondered what the reason was for the full throttle shutdown. Makes sense now.

My Timecutter HD says to shut down at FT on the sticker next to the key. So that’s what I do. Toro branded (Loncin) V twin.

 

[WinterDeere]

Well, fuel pump is good, and still waiting on spark gap tester, so I went to measure crankcase vacuum, and found it’s at positive pressure. Thinking back, I remember replacing the breather maybe 10 years ago, so I guess it ate another one.

Trouble is, you have to remove flywheel and front motor casing to get at it.

Sounds like you got your moneys worth from that motor

I don’t prescribe to that mentality. I have plenty of motors older than this, and with way more than these 1200 hours.

Compression was checked cool, because I did t want to run long enough to warm it up fully, but shows 75-80 psi. Spec is 57 psi min.

 

[WinterDeere]

Just thinking, I should probably look up leak-down specs for this motor. The high compression could be due to carbon build-up, and not really a good indicator that there’s no blow-by issue.

 

[Yander]

Have you changed the fuel filter. $4 part.

 

[WinterDeere]

Have you changed the fuel filter. $4 part.

Every 12 months. Last change was beginning of this season, about 60 hours ago.

Maybe you just responded before reading ahead, but issue has already been diagnosed to positive crankcase pressure.

 

[WinterDeere]

so here’s a question: what causes these breathers to fail? Getting to the damn thing is an all-day job, engine removal, always precarious with fragile 20 year old wiring harness connectors, flywjeel removal… damn near half the engine is apart before you can even access the breather. Not something I want to repeat too often.

What causes breather failure? Backfiring on shutdown seems like a potential culprit.