Monday, August 22, 2016

happiness is another small engine - part 2

It has been nearly a year since I decided to buy a 4-stroke leave blower against the common wisdom. Upon first receiving it I was very pleased with its performance, and especially how quiet it is. Even at full throttle I find it no need to wear any hearing protection. The other benefits are the cleaner exhaust and without having to deal with gasoline and oil mixture. I was also very impressed on how little fuel it consumes - until a few months into the ownership.

After a few month of use, I begun to notice the gasoline in the small plastic tank consumption had jumped. I vaguely remember it was just a half tank when I put the blower away. When I went and use it the next time, the tank was completely empty. I also notice a wet spot on the concrete where the blower sat. Feeling around the bottom of the blower with my hand I found wetness. The liquid felt almost like a gasoline and oil mixture. Not good, I thought, but not knowing what might be the problem. May be a design deficiency? I was too overwhelmed with other things to get to the bottom of it.

i placed a paper shopping bag under the blow to detect fuel/oil leak after use

In the early summer I grudgingly pull out the blower as I really need to use it. The fuel tank by now was completely empty. Knowing the 1-year warranty is rapidly running out, I really wanted to get to the bottom of the problem. I turned the blower upside down for a good visual inspection of the plastic fuel tank, as well as to see if there is any trace of the source of the leak. To my surprise the bottom is bone dry. I then checked the oil in the crankcase. I was expecting it must be quite depleted. No. The oil had hardly been consumed. The plastic fuel tank also has no crack or delamination at the seam. I even applied suction with my mouth to check for leakage just to be sure. With no obvious sign of defect, I fill the tank up with gasoline and just a few pulls the blower was up and running.

As I want my equipment to last, I always take very good care of them. This blower is not an exception. I always use it for a minute or so leaving it at idle before opening up the throttle. I thought may be my low RPM use of the blower is the cause of the seemingly leak problem. Rich idling and the engine may not get to proper operating temperature. It would turn out this is not the cause...

The blower worked flawlessly this early summer, and up to now. There is no more mysterious disappearance of gasoline nor lubrication oil. To me the cause cannot be more obvious. The disappearance of the gasoline was due to a stuck carburetor float or stop needle. This prevented the carburetor from functioning normally. The stuck carburetor float or stop needle allow the gasoline to be siphoned from the fuel tank. When I turned the blower over to check for leak I un-stuck the float.

It has been a few months now and the blower works flawlessly. I am extremely pleased with my decision for a 4-stroke over the 2-stroke variety. I came very close to opt for the 2-stroke Stihl BG55. Typically the rule of thumb is of same displacement 2 stroke engine can generate nearly twice the horsepower of the 4-stroke, if both are tuned to the max. The quality of this blower is professional grade, despite the consumer price point. It is also extremely easy to start, even after a long storage period unlike a lot of 2-stroke engines which the carburetor metering jet has a tendency to be clogged by the oil as the volatile component of the fuel mixture evaporated.

You can find only a few video of this blower on Youtube. None does justice on its performance. A problem with these video is because of the quietness the videos give the impression that it is extremely underpowered. When I compared it to my neighbor's Stihl BG55 that costs within $10 of the Makita the Stihl is slightly more powerful but much louder. The Stihl is a 2-stroke which is a lot cheaper to manufacturer. Oh, if you are one that comparison shop by the "spec" do not bother with this Makita as it is lackluster in the MPH or CFM claims. Moreover it is $50 too expensive if advertised spec is how you assess a purchase. My hint is look at the two blowers side by side, assuming you have the eyes for quality. To me the comparable 4-stroke blower is the one made by Honda, which is not sold in this country because the consumers here want it all, and want it at rock bottom prices.

Here is the advertised specs of the Makita and the Stihl. The Makita is 0.9 lb heaver. It has a bigger fuel tank, and slightly smaller engine displacement. Needless to say, I was shocked to experience its performance against the Stihl BG55 which I regard as the benchmark. When comes to comparing performance specifications such as air speed, CFM, sound level, and output horsepower I am generally very skeptical as most often, the test conditions and methodologies are like comparing apples and oranges between different brands. For leaf blowers the most abused parameters are maximum CFM, maximum air speed, and noise level. The least appreciate attributes are the build quality, ergonomics, reliability, and long term cost of ownership.

Makita BHX2500 specs

Stihl BG55 specs

Honda 4-stroke blower that is very comparable to the Makita but costs more than twice

And for entertainment, here is one "technical" article on 2-stroke vs 4-stroke blower. The author obvious has no business in writing about this subject. I am however would be very impressed if it is written by a bot.

I would really like to compare this Makita side by side with the Honda. For what's worth, here are videos of the two on Youtube:



Based upon the video and the product photos of the Honda, I infer the Makita is a better product overall. This blow has the MM4 engine that Makita is very proud of. Here are the videos of the engines for what they are worth. One reason gasoline powered gardening tools are predominantly 2-stroke or hybrid 2/4-stroke design is weight and cost, and the challenge of lubrication as the engine is not always upright.

makita - it is a rather poor marketing video; to me the diagram at 0:22 is most significant depicting the lubrication design


Reading between the lines, I infer that the Honda engine is designed for sustained operation in 360-degree orientations. The Makita MM4 may not be. Makita does not make tools based on this engine that requires to operate in inverted orientations but Honda does.

Interestingly the Makita 4-stroke blower line of product manufacturer was formerly known as Dormar in Hamburg, Germany. It is one of the oldest companies that manufacturer gasoline powered chainsaws. It was acquired by Makita in 1991. Up to recently this identical blower also was sold under the Dormar brand at about the same price. The color of the engine cover is orange instead of blue.

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