New X300 puffs black smoke at warm start

[TreasureHunter11]

How about the occasional puffs of blue oil smoke at cold start up? I have read this can be typical for twin cylinder engines. I have a single cylinder Kohler Command on a mower that has not smoked any in the 13 years I've owned it's actually a 1999 model engine that was used when I got it, likely has well over 1000 hours on it, if it smoked it is to be expected but on the new Kawasaki I'm not fond of seeing any smoke especially with the hefty price tag they carry and with so little hours but this is my first twin cylinder mower

 

[Hubsn]

Hi TreasureHunter,
I´m from europe and have bought a X305R this winter. It was from a dealer with 17hrs on it and about two years old. So not really used - just for opening of a new market so kids were able to ride on it. the first times I used it it was fine this year in months march and april. But the last times I use the mower I have always same problems.
When its cold it starts fine - and it works perfect. I use for one or two hours and no problem at all! But when I park then and try to restart again it is really hard to restart. Almost no way to bring up again. Black smoke, need to start and start and start and then very weak and like an 100 years old traktor starts slowly to come up. I runs very weak for about half a minute. Then it gets turning and slowly getting enough turns.... then its fine again and can run another hour.... I really would like to find out whats the problem.
What I can see is that in the gasfilter is usually filled most with gas - and after hot running there is more and more air in it. Is that normal?
I havent changed anything on the mower now. What could be the problem?

Best regards
Hubsn

 

[billymagg]

Our old 172 had sat a month, we started it Wednesday, after a couple of plungers full of fuel on the primer, I'm sure it smoked, and it ran rough for the first 30 seconds??? so whats the problem, every general aviation aircraft I know of requires primer, and no doubt they all tend to start rich and smoke a little??? so what, most recips require a primer shot to start.

If you want a thrill watch a radial engine start, oil pools in the bottom cylinders then burns out rapidly as the engine starts, I would relax and keep tabs on oil consumption. In my honest opinion, you don't have a problem, other that obsessive compulsive disorder???
:confused2::confused2::laughing:

 

[TreasureHunter11]

Hubsn, If yours has the Kawasaki there is a black spring operated choke lever on the left side of the carburetor, insure it is in the down position by gently pushing it down with your finger. It should go up with the use of the dash choke lever and return under its own spring tension. Mine has a issue with sticking closed which the dealer suppose to fix next week which is unrelated to my rich restarts, I have insured the choke is fully open. Not seeing much fuel in the filter is normal

 

[TreasureHunter11]

Well second trip to the dealer fixed the sticking choke which is a issue by itself and not related to the over rich hot restarts without choke. The Dealer could not duplicate it, they did go through the carb and found nothing. They lowered the idle set screw. Today I tried it hoping they fixed it and sure enough after mowing for 30 minutes I lowered the idle & shut it off to take a break, 5 minutes later I restart it and it's puffing black smoke and idle is erratic but clears up once it is throttled up

 

[billymagg]

Well second trip to the dealer fixed the sticking choke which is a issue by itself and not related to the over rich hot restarts without choke. The Dealer could not duplicate it, they did go through the carb and found nothing. They lowered the idle set screw. Today I tried it hoping they fixed it and sure enough after mowing for 30 minutes I lowered the idle & shut it off to take a break, 5 minutes later I restart it and it's puffing black smoke and idle is erratic but clears up once it is throttled up

So the dealer is telling you he cannot replicate the problem, but for you, every hot start result in this over-rich condition, engine loaded up as indicated by the black smoke and erratic idle? so it really sounds like its possible the idle jets are too rich, which is better than too lean. THunter, how many seconds does it take to "throttle up", as I crank a hot engine, I almost always advance the throttle if I don't get an immediate firing condition? If you are attempting to start at idle, its possible that your engine is not making enough vacuum initially to get sufficient airflow to run smoothly.

The reason I mentioned aircraft, is because they are notoriously hard to start when hot, heat builds under the cowling, and if its on the ramp, the black pavement can create intake air of 115 degrees or so. On the old Piper Tomahawk,,, with the T-tail, it took a special knack to start some of them after they became heat soaked, they are low wing so there was an electric fuel pump, I recall a customer who couldn't get his to light, so I had to help him. I don't remember the drill as it was 20 plus years ago.

When I shut down in the heat, I sometimes allow the engine to idle around 1000 rpm, which is higher than normal idle, and perform the "mixture idle cut-off", our aircraft has a very effective mixture control, and the little higher rpm when the fuel is shut off allows the engine to turn through a few more blades, purging the cylinders of excess fuel.

In contrast the Ercoupe I fly, the CFI/Mechanic asks that I not use "mixture idle cut-off" but simply turn the switch to off? strange to me, but it works.... I have flown aircraft and maybe the Ercoupe is one of those, where the mixture is pulled full lean and they never completely seem to shut the fuel off, and the aircraft has a "run-on" condition, chuffing and huffing and generally sounding like something is about to blow??

So, my suggestion for you, is to try a little higher throttle setting for starting/and or shut down, not full throttle, but a couple of hundred RPM above the idle speed and get back to us on whether that might help, be sure to shut down the PTO, Hydraulics, etc before shut-down, if you have the lift lever somewhere that it is trying to spin a little hydraulic pressure, you could be loading the engine inadvertently??

 

[TreasureHunter11]

Correct the dealer couldn't replicate the issue, the temps were in the 80s that day not ideal conditions for it to happen which I explained to them, it has to get hot/mowing and temps 90+ . I've owned many mowers in the past and this is a first for me and worked on small engines for many years. All winter it is trouble free, no matter how much it's run and shut off and restarted. I've went by the manual half throttle shut downs as well as lowest idle & makes no difference. The muffler is about 3 inches under the carb bowl separated by a metal plate and that plate gets sizzling spit on Hot! I feel like the fuel is boiling in the bowl but just my opinion. If they had some grass to mow on a 90+ day I could replicate it for them but they don't. Funny thing the choke lever operated fine cold, I could walk in my shop at night or any cool day and the lever would work perfect, get the mower hot, shut it off for say refueling and it would stick in the closed position. I never use the choke to start it other than if I run out of fuel, which is how it was discovered as a issue. 2 weeks ago prior to running the engine I opened the hood and operated the choke many times and it worked perfect, it has it's own spring on the choke shaft so it closes without cables, basically a lever pushes up on the plastic arm mounted on the choke shaft and when the dash control is released the choke lever opens under it's own spring tension... I run the engine about twenty minutes and shut it off, opened the hood and operated the choke and it worked perfect, waited a few minutes for the temp to peak and tried the choke again and it would stick in the closed position every time until the engine cooled. The guy at John Deere pretty much sanded the plastic choke shaft. When I took it off the trailer it operated fine & the mechanic said I see nothing wrong so I started the mower and drove it around the parking lot, idled it down & shut it off, tried the choke and it worked perfect, I told the guy to wait and sure enough after 3-4 minutes it stuck in the closed position and took effort to push it back open.

 

[TreasureHunter11]

Pretty much to sum it up it runs perfect in the winter including the choke "zero issues". Summer 90+ temps it starts fine without a choke, runs great mowing. Shut it off 5-10 minutes for a break, restart it without choke at half throttle and it fires up and puffs black smoke "over rich condition" but slowly levels out as throttle is increased, instant restarts hot it does not occur meaning if I reduce throttle shut it off and restart, if it sets say 30 minutes after mowing it starts fine without and issues. Was the same with the choke, only sticks when hot and has set a few minutes. I've even run it without the hood and it still occurs. The dealer checked the lowest RPM and it was at 2400 which he said was incorrectly set by Kawasaki so he set it to factory spec of 1800 RPM & felt like that contributed to excess fuel being drawn into the intake seeing I was shutting it down at the lowest RPM the dash lever would allow so instead of 2400 it was now 1800 & I thought that was the fix but it still occurs after using it yesterday. I'm puzzled as is the dealer as to what is causing it. I think sanding the plastic shaft "dressing it" as they call it was a bandaid to the actual issue. How can this choke shaft operate perfect cold but not hot??? I works fine now that they have sanded it...