Kohler K321 on a 1450 backfires and stalls.

[mikeangelini]

I bought the Mystery Oil. Just a cap per full tank is enough?

After it backfired hard, it did run fine on the same plug, but I am going to try a new plug tomorrow.

I have the coil, but maybe I will replace the plug, and use Mystery Oil, and see what happens.


How long will it take till the Mystery Oil will help?

The fuel line seems fine. In fact, everything was fine for the first 35 minutes.

I will report back what I did to it, and how it goes after mowing tomorrow.

Thanks a lot.


Mike

[samiam44]

I think it says 1 oz/gallon.

Some add some to the oil too- maybe an ounce or 2.

I'd say mine ran much better after 2 or 3 tanks of fuel- and I wasn't having issues. I think it just helps clean out carbon + mine was way rich due to a plugged airfilter.

I would change oil at a more frequent rate using something that is detergent- I like Chevron Delo (30wt or 15W40).

Michael

[mikeangelini]

Great, thanks. I hope the Mystery Oil is able to help my engine run better.
Looking forward to an 'incident free' day. I think she will be fine after a few more small fixes. Hoping not to have to pull the engine apart this year.

Mike

[CADplans]

My 149 used to do that back in the late 1980's. You can't blame it on ethanol fuel, I do not think it was around then.

Mine was 100% repeatable, pushing snow with a 54" blade coming up my driveway at full throttle and as much hydro as the engine could take, after about 3 to 5 minutes it would backfire and quit.

The tractor would immediately restart, it would be able to run for the same 3-5 minutes before another backfire.

I had not learned about MMO back then, but, I learned to back off the hydro a little each 3 minutes or so, and it would not do the backfire/quit routine.

I still have that tractor, it hasn't ran since the mid 1990's. Maybe some day I will get it out and try the MMO to see if it will fix the tractor.

I did not quit using it because of a problem, I just got a larger tractor and parked the 149.

[dclinansmith]

I had the same problem that you are having with my 149. After almost every stop if you just stood beside the tractor you would hear the exhaust valve snap shut when it cooled down. It would only be a couple minutes after shutdown, then it would start right up again. I removed the air filter cover and the filter. Put some MMO in a squirt oil can, run the engine about half throttle and squirt the MMO into the carb. I fed mine enough to almost choke it down, when it clears up a little do it again. I did that several times then reinstalled air filter and ran it a short time then I repeated the procedure. I run MMO in the gas now and haven't had a repeat of the problem. My 149 has been a great tractor with almost no issues in its entire life. I do have one advantage over a lot of owners, I bought mine new in 73.

[mikeangelini]

I spent a couple hours this weekend working on the tractor, and I was able to cut the lawn at full throttle with no issues.

I did replace the coil. The old one sounded like it had water in it and something was shaking around in it. Not sure if it was shot, but since I have limited time to work on it, I wanted to cover more stuff at once.

The back of the engine had dried grass clogged up in there. I scraped out as much grass and soot as I could with a screwdriver and shop vac'd it out. I would like to completely clean out all around the engine. The fins were clogged up with soot, etc as well.

What is the best way to clean it all up in there? Without taking the entire machine apart?

I changed the spark plug. The old one was really old. Gap at .030".

I put MMO in the gas and oil.

Ran really nice. Thanks for all the suggestions. Not sure which issue was causing the backfire. Maybe a little of all? OR maybe it will do it again. Hoping for the best.

Thanks,
Mike

[Sam Mac]

Originally Posted by mikeangelini

The back of the engine had dried grass clogged up in there. I scraped out as much grass and soot as I could with a screwdriver and shop vac'd it out. I would like to completely clean out all around the engine. The fins were clogged up with soot, etc as well.

What is the best way to clean it all up in there? Without taking the entire machine apart?

It's a PITA to pull the engine to clean it but it's better to do it than having to pull it because you cooked it and have to clean it anyway. Kind of like the old filter add " You can pay me now or pay me later" I like to pull an air cooled engine every couple years and clean it.