Honda: (My direct experience comes from working on a customer's who had a system with a Honda 24. I learned all about the valve adjustment "stuff" where Honda is concerned, because Honda wouldn't honor the warranty, because he didn't get his valves adjusted. So I learned how and did it for him) They're good motors, but... The valves have to be manually adjusted periodically (one dealer recently told me that it's every 300 hours) hours (by an authorized repair center), or the warranty is null and void. (Briggs and Kohler use hydraulic lifters, which are self- adjusting, so this isn't necessary with their design.). In my experience, someone who works full- time as a cleaner puts about 25 machine- hours a week on their system. That's just over 100 hours a month. So, at 300 hours, in order to keep up the condition (and warranty), it would have to be taken in every 3 months. And, at least over here in the U.S., if there's a problem with one, they take the position that it must be operator error, because they build "such good motors", that it's very, very likely not a problem that can be traced back to Honda. If you have one, keep meticulous maintenance records and get the valves adjusted as required. You'll need to prove it all if there's a warranty problem. Briggs (My experience is from building systems with them for 5 years, and was with the 16, 18, 20, 21 and 23's.) Briggs (and Kohler) is much better in the area of warranty. But one of the things in my experience (I quit using Vanguards and went to Kohler in 2001) about Briggs is constant oil leaks. They leak early on... like as early as 3 weeks out. But as long as you keep oil in them, they run. For some reason Vanguard 16's are an exception. I don't know if they're made in a different factory or what. But they last longer and have fewer oil leaks, than the other ones I've had experience with. They also have weak starter solenoids. They were in denial of it in the late 1990's, then said that "some" near the ocean were giving problems and started to look at the problem. From what I hear, it's still a problem. If the solenoid goes out, it's inexpensive ($15.00 or so) to replace and easy to jump across with a screwdriver. Kohler (My experience comes from building systems with them (18, 20, 22, 25 and 27 HP models) from 2001 until now...) Very few oil leaks. (I've seen 2 on new motors. One was a loose clamp on an oil cooler (10 seconds to fix). The other was a rear main seal that apparently got damaged on installation at their factory.) On older motors, leaks are still rare. Their starter and starter solenoid rarely, RARELY have any problems. And Kohler, for heat exchange systems, delivers more heat than Briggs or Honda. Kohler runs at higher compression, has a longer stroke and has more cast iron in the motor than the others. Higher compression causes it to run hotter. Longer stroke gives it more CFM (more BTU's). And more cast iron means that it retains more heat, vs. losing it to the air more quickly. Kawasaki: (My experience comes from experience with a PowerClean Victory that used to use them. And, from a good friend of mine who is a certified mechanic for Briggs, Kohler, Robbins, Kawasaki and Honda.) For some reason, they simply haven't held up well in this industry. I think it has to do with their back pressure tolerance. They don't seem to do well working against back pressure typically found in heat exchange systems. As a result, they suffer blown head gaskets, burned valves, bent push rods and a myriad of other things. My friend Rob says they they're very good motors in the lawn care industry. And he doesn't know why they wouldn't do well in ours. Nevertheless, to my knowledge, no manufacturer of truck mounts uses them at this time and some have in the past. Water cooled... I was speaking with my Kohler rep about water vs. air- cooled. And I asked him about the two things that people say about them. 1.) They're quieter 2.) They last longer. He chuckled and said, "Not in my experience.". The piston goes up and down in the cylinder only a certain number of times. If you want to lengthen the lifespan. Reduce the RPM, so that it goes up and down less in a given period of time. But you can't do this if the motor is "matched" to the torque requirements of the system. It has to have more than necessary, so that running it slower will not drop the available power below what is required. In my opinion, the reason water- cooled motors are common in our industry is because they have heated coolant which can be used in a liquid- to- liquid heat exchanger setting, providing more available heat and one that is more or less, "automatic", since the temperature of coolant is typically lower than (190 to 210) the desired temperature of cleaning solution. Also, larger motors tend to be water- cooled. And with the big push for more heat in systems, engineers often look to larger components (blowers, which require larger motors) for more available heat. But for single wand systems... ? I don't see the merit of running a 30 HP / #5 blower system for one wand. More study should be spent on how to scavenge heat more efficiently, instead of simply rough- trailing it with bigger components for a single- wand system.