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Discussion Starter · #1 ·
I bought my 2019 X730 last Aug with 70 hours on it. I did the complete 90 hour maintenance as prescribed on time. A few weeks later, I felt the engine had a slight miss so I pulled the plugs ( had not changed them @ 90 hours) and found them to be very black and "sooty". I changed the plugs and the engine runs like a top. I did notice that the exhaust is spitting black soot out onto the back side of the plow for a few minute after initial starting. I should mention that I added a quarter of a bottle of TECHRON to the 91octaine (top tier) gas that I use after I changed the plugs. So I've added about 5 hours to the clock since I changed plugs and added the Techron to the gas. I haven't pulled the new plugs out yet to see how they are doing yet but will soon.
Just wondering if the black soot is simply a result of the Techron cleaning out my injectors, valves etc, or is the fuel injection system not providing the proper mixture of gas/air and causing this situation? Any other issues you can think of? Thank in advance, Ron
 

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There is lots of talk about where the throttle should be while starting the machine. General consensus seems to be at least half throttle. I know when I start my X738 at half throttle is starts much cleaner with less soot than if I start it with the throttle in the idle position. I'd give that a go if you aren't already.
 

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Owners manual says to start at half throttle. The engine will start at idle but that leads to smoking and carbon build up.
Engine starts much cleaner at half throttle.
 

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Discussion Starter · #4 ·
You are both very helpful. My 65 years experience with gas engines drives me to start all my equipment at 1/4 throttle even though I knew that JD recommends 1/2 to 3/4. I WILL change my starting procedure to the manual, as well as your recommendations, and hopefully see a big improvement in the amount of soot being emitted and on the plugs.
Thank you both for the quick replies, I really appreciate it!
 

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.... I did notice that the exhaust is spitting black soot out onto the back side of the plow for a few minute after initial starting....
I know what you mean. First few times I started my x738 (throttle set at idle, exhaust pointing towards a finished drywall) I didn't realize what it was doing to the wall - only realized later when I saw a nice black splotch of carbon specks peppered on there. I now start it at probably 70% throttle and have a piece of cardboard taking the brunt of it and guess what..it still coughs out carbon on startup. IMO these aren't very clean running machines - they may be fuel injected but they run in open loop meaning it doesn't adjust to maintain a specific air/fuel ratio like a car or truck would. It might be self-induced though because I leave it idle for 5 minutes or so after I'm done using it while I clean off the snowblower/plow, etc. and then idle it back to the shed - maybe that's enough to cause the buildup I see next time I start it. I think these things are expected to run at or near WOT not putting along at idle.
 

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You might want to run some SeaFoam through the fuel system every 10 hours or so. It does a very good job cleaning the injectors and other components. For those who end up with smoke stains on implements, etc, you can remove much if not all of the exhaust stains with Dawn dish soap with very little effort.
 

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Discussion Starter · #8 · (Edited)
Thanks Sulley. I normally use Techron in my engines. I actually put a quarter of a bottle in the tractor a few hours ago and I'm wondering if that's why I getting such a sooty exhaust. I am familiar with SeaFoam, however, have never tried it. The exhaust stains seem to wash right off with a rag and clear water. I appreciate your suggestion and if it continues to carbon up the plugs I'll try some SeaFoam
 

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I'm just guessing but I think condensation collects in the muffler as it cools down and then on next startup it sprays the sooty water out. My X739 has done it since day one with 1 hour on the clock so I don't think its because the fuel system needed cleaning, at least on mine.
 

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Discussion Starter · #10 ·
Eric, I tend to agree with you as I went out and started the tractor this afternoon and it only sprayed sooty water for 15-20 sec's and ran clean after that period.
 

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On little thought I'd like to share. When planning to remove the plugs for a read, run the engine at WOT, after a sufficient warm up, and turn off the engine without throttling down, for the most accurate read.
 

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Discussion Starter · #12 · (Edited)
mrmagloo- thank you, the is new information to me. I though perhaps removing a plug from a hot head/block might not be the best thing for stripping out the threads in the aluminum head/block. That assumes, of course that the KAW engine is aluminum!
 

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To be clear, you do not need to immediately remove the plug. Let it cool off a bit. That will not change the coloration that is only effected while the engine is running.
 
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