New X300 puffs black smoke at warm start

Would be nice to know what engine your machine has on it. Definitely let a dealer deal with it as it is still on warranty. My spin on it is a carb problem possibly the float set a little too high. Is the muffler tail pipe sooty with dry or damp soot?
 
It has the Kawasaki FS600V,the exhaust has some black soot indicating a rich condition.Called my dealer a month ago and he said it may be my fuel and to run this tank out,refill and see how it does.I have a bit over a gallon to go,thought about adding some fresh 93 but at 2.7 hours it was doing this and the fuel was fresh.Was hoping I could solve it instead of taking it to the dealer,I've had bad experiences with dealerships and service depts "LOL"
 
Your problem needs to be addressed soon as a rich fuel mixture washes the cylinder walls and the engine will never break in. It could a simple thing like the choke plate not fully opening or could be a major problem with the carb. This excess unburned fuel slowly dilutes the engine oil the result of which is early or premature engine failure.
I understand your apprehension about service departments, I was an outboard/power equipment mech in the 70s. With the exception of 24 years in the military, I have been a service dept mech in several local small businesses including aircraft until I retired.
Diagnosing problems has turned into just parts changing until the problem appears to go away. This is the primary reason that companies are increasingly critical of warranty requests from dealers and are rejecting an increasing percentage of them.
Mad Mackie in CT:laughing::biggrin::smile:
 
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Ok I purchased my mower the first of May of this year,it had about 1 gallon of fuel from the dealer but did not use the mower until the the middle of May waiting on replacement tires "new tires had cracks" after getting the new tires I added a gallon of 93 gasoline,I used the mower for about 1.5 hours and at the end of June filled it up with 93,used about a half tank and filled it up again the end of July,now with 6.5 hours on the mower I had about a gallon of fuel left from the last fill up so today I purchased 2 gallons and added to the tank.Is it possible my fuel is bad even though I have been topping it off? We have had a lot of rain and a large portion of my yard is wet so I only cut the front with the Deere and use my old mower for the wet mess that's why my hours are low.Every week since I purchased the mower I would start it up and drive it just to keep fuel from setting in the carb bowl and to keep the battery charged.My dealer is clueless after speaking with him,he tends to lean toward trash in the bowl seeing my issue is intermittent,he is a week behind in work and said it would be next week before he could look at it.
 
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TreasureHunter11 said:
Ok I purchased my mower the first of May of this year,it had about 1 gallon of fuel from the dealer but did not use the mower until the the middle of May waiting on replacement tires "new tires had cracks" after getting the new tires I added a gallon of 93 gasoline,I used the mower for about 1.5 hours and at the end of June filled it up with 93,used about a half tank and filled it up again the end of July,now with 6.5 hours on the mower I had about a gallon of fuel left from the last fill up so today I purchased 2 gallons and added to the tank.Is it possible my fuel is bad even though I have been topping it off? We have had a lot of rain and a large portion of my yard is wet so I only cut the front with the Deere and use my old mower for the wet mess that's why my hours are low.Every week since I purchased the mower I would start it up and drive it just to keep fuel from setting in the carb bowl and to keep the battery charged.My dealer is clueless after speaking with him,he tends to lean toward trash in the bowl seeing my issue is intermittent,he is a week behind in work and said it would be next week before he could look at it.
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Let the JD dealer fix the whole thing. Cut with your old machine while it is in his shop.
 
Well after two visits to the dealer my issue still exist. They could not duplicate the issue, they checked everything and found no problems after keeping it for almost 3 weeks, he even checked in his system for other mowers sharing this issue and found none. The shop mgr said they put enough time into it... I may be wrong but after some thought I think it's the design of the exhaust heat shield below the carburetor bowl combined with the lower boiling point of ethanol blended fuels, when the engine shuts off it generates more heat causing the fuel in the bowl to boil creating fuel vapor. The muffler and heat shield is very close under the bowl. At 30 hours on the clock it still continues. It starts fine cold, it runs great mowing and instant hot restarts are perfect, say a minute or so to grab a soda but if it sets for 5 minutes it will puff black smoke for a split second, run a bit rough and clear up. If it sets 30 minutes no black smoke so it's gotta be heat related, the boiled over fuel vapors evaporates but that's my take on what's happening. This winter I used the mower and it was flawless on hot restarts but now that temps are in the 80s it's starting again, the hotter it is the more prone it is to occur. I may try non-ethanol fuel and see if this resolves this ongoing issue just to see if it helps. My mower has the newly designed hood, I recall the dealer mentioning it was the first he had seen when they uncrated it, perhaps the old design allowed more airflow, suppose I could try running it with the hood off and see if it makes a difference. Is it normal for these Kawasaki engines to "occasionally" puff blue oil smoke at cold start, I've had it happen 3 times? I've changed the oil twice by the book at 8 hours & 1 year interval and the oil level is dead on & not overfull. I read somewhere the way the cylinders lay this can happen depending on where the piston stops? I asked the dealer about this as well and he said it is still in the break in period and can happen. I agree with Mad Mackie, eventually this extra fuel/vapor will eventually cause wear on the cylinders but not much I can do when the dealer cannot find anything wrong which is my issue.
 
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Just throwing this in. Just because its higher octane does not mean it ethanol free. See if you can find ethanol free gas and remove all the old gas and replace it. Including in the carb bowl. If ethanol free is not available then just run 87 octane. Higher octane fuels can be "old" when purchased because of low need for them. They can sit in big underground tank for over 90 days before someone buys it.
 
BlazNT said:
Just throwing this in. Just because its higher octane does not mean it ethanol free. See if you can find ethanol free gas and remove all the old gas and replace it. Including in the carb bowl. If ethanol free is not available then just run 87 octane. Higher octane fuels can be "old" when purchased because of low need for them. They can sit in big underground tank for over 90 days before someone buys it.
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Correct, I was planning on going from my current fuel which contains ethanol to 91 non-ethanol, now that you mention it with high fuel prices I imagine it does set there longer, good tip. Thanks
 
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