captinjohn

It has been said that a lot of the new RC engines have problems of all types. Some do not last only a very few flights & they develop loss of power, loss of compression or general crappy running & even die. On the other hand most yard equipment takes a licking & keeps on ticking. See it a lot. I bought 2 MB 290 leaf blowers($49 each) and run them wide open most the time. Five years later they still run great with good compression. I use Pennzoil 2 cycle for air cooled engines. Also tried other good oil brands in them....no problems. Why do many RC Hobby engines end up crap or need a lot of re-doing????? Big money for them & I feel RC people are getting shafted.

Capt,n

Truckracer

My Feedback: (19)

Capt'n, it really isn't all doom and gloom in the RC engine world. Certainly, as the Chinese engines came on the scene some years ago, they started out being of questionable quality but most of the surviving companies are today producing quite good engines. Certainly there are still some crappy engines out there but the brands that have been around awhile and even some of the newer ones are actually very good engines these days.

So why does there seem to be more problems with these engines than similar yard equipment engines? I'd suggest that much of the time the problems are caused by the users and the environment our engines are used in. Every piece of yard equipment comes equipped with a cooling fan and a nice, tight fitting shroud so these engines always receive good cooling. By contrast, our airplane engines many times just get stuck on the front of an airplane with little thought to how they will be cooled .... with little or no baffling, etc. Add to this weak firewalls and user inexperience and parts (mufflers) may fall off from time to time and needles are often poorly adjusted. We have users that still insist on using 100:1 oil mixes when 32:1 or 40:1 is better and more forgiving for most users. Then of course some of our engines crash which further complicates their existence.

Yes I suggest that experienced users have few problems with their engines because they know how to create an environment their engines will be happy in. Give an inexperienced user a high quality DA, 3W, MVVS, etc. engine and the lifespan of that engine will be greatly reduced.

Even here on the forums, people ask questions then many times choose to ignore the advice given by those who have much more experience. Many experienced people have gone away simply because they are tired of wasting their time answering questions for those who don't care to hear the answers.

So yes, I firmly believe in the case of your question and statement, it is more of a user problem than a hardware problem.

geeter

My Feedback: (110)

Your right capt'n. A 99.00 weedeater can run three, four seasons without problem. Yet a small 20 cc gas airplane engine can't even make it off the test stand like my 20 cc....vvrc engine I have been waiting three weeks to get back. I thought Chinese junk was a small boat........

captinjohn

[QUOTE=geeter;12122738]Your right capt'n. A 99.00 weedeater can run three, four seasons without problem. Yet a small 20 cc gas airplane engine can't even make it off the test stand like my 20 cc....vvrc engine I have been waiting three weeks to get back. I thought Chinese junk was a small boat........[/QUOTE
Truckracer...I know I am right....been working on many engines. getter knows what I am talking about. For a test I removed the tight air ducting on my MB 290 leaf blower engine long ago. It still has high compression & power....I can post a photo of it so you will not doubt it.....

ahicks

My Feedback: (2)

I'm not sure what the issue is? Not on board with the doom and gloom either. AND, I refuse to compare a fully ducted piece of lawn equipment (modified or standard), with a carb that's not adjustable, to a modern engine intended for RC aircraft?

No clue why geeter's engine was sent back to VV. Even if it does turn out to be defective hardware (rare in my experience), so we don't live in a perfect world! Ever seen the stack of returned lawn equipment at a big box store selling it?

I'm with TR. Take away the people that refuse to RTFM, or be in possession of an open mind regarding proper installation and tuning, and I think what we have available to us not all that bad. -Al

Truckracer

My Feedback: (19)

[QUOTE=captinjohn;12122754]I'm speechless!

Truckracer

My Feedback: (19)

I would say that buying an RC engine is similar to buying any other product. Is it recommended to go out and buy the first "no name" product you can find? Do you research the marketplace before buying a new TV, washer, car, etc. Sure, most people do. Some people are willing to take a change on an unknown brand where some people prefer to buy what they are familiar with. We make our choices and take our chances. Some work out well and the product is a good one, some not so good and the product goes away and yes, those early buyers may have felt stung in the process. That is just the marketplace in a free society. Some little known RC engine companies have produced good products and have gone on to be mainstream brands today. Others not so much and they either go away or resurface under a different name to try again.

So Capt'n, how are RC engines so different than other products we buy? Also, how is today's RC engine market so different than it ever was? I can pull out a drawer of some pretty crummy engines purchased over the decades ....... and some darn nice ones also. Pull out a few copies of model magazines from the various decades and you won't have to look very far to see many engines advertised that never made the cut in the marketplace. Some were good and some were ..... very bad!

So, I really don't see the point of your original post and this thread as a whole. Pretty much a waste of time and time I could have spent better than writing this response. But being retired, I guess I have the time to waste.

irocbsa

My Feedback: (12)

I thought about replying with the exact same thing as I had to raise my jaw up off the floor with a ten ton jack after reading all this nonsense. I then realized that this thread was started by a guy who has 12,000+ posts and still has trouble logging in with the proper user name or recognizing that the threads he posts irrelevant information in are 15 years old. Let's all just move on. Argueing in this thread is clearly a wasted effort.

OP, some unsolicited advice:

1. Take an "Internet 101" class at a local community college and then get back to us.

2. Learn proper grammar and punctuation. After that, get back to us.

3. Learn about simple physics and why a weedwacker Homelite is funadmentally different in construction, metallurgy, operational characteristics, and intended use from a model aircraft engine. Discovering fundamental principles such as these might give you a hint as to why RC engines behave differently than lawn equipment. After that, get back to us.

captinjohn

Listen iro from Ann Arbor, I have Carpal Tunnel in both hands. Just beginning to get the use in very numb fingers. So back off. Very few people on here have perfect grammar. Also did you stop to think all computers work perfect. This Windows 8.1 will jump back when I are typing.

Lets talk engines, not how or what you think of other folks when they post...get real........

irocbsa

My Feedback: (12)

What? My head hurts after trying to read that. Perfect grammar isn't required, but legibility is. Seven periods are not necessary after every sentence. I'll start "getting real" when you start making relevant, legible, and helpful posts.

geeter

My Feedback: (110)

sounds like a GAS....................

dirtybird

My Feedback: (5)

The answer to this question is obvious.
A yard work engine is purposely made oversize and overweight for the purpose to begin with. Then the carb has fixed jets and the ignition is set to produce maximum torque ,not max RPM. the throttle is limited to safe RPM
It also has a cooling jacket and a filter on the air intake.
A hobby engine has none of these and maniac on the throttle..

crashmaster5000

My Feedback: (1)

I am absolutely taken aback with the derogatory comments on this thread. Have we sunk so far into the abyss of grammar Nazism that we feel the need to critique each other's typing and communication skills? It doesn't matter how Captinjohn expresses his ideas, he has a valid question and deserves input RESPECTFULLY.
I happen to agree with Captinjohn, I fly the same MB290 engines with a 18-6 prop at 9200rpm with a FULLY adjustable carburetor, velocity stack and electronic ignition. I have never had a problem other than running out of fuel from flying for 32 minutes. There is no cooling fan or even a fly wheel, no air ducting or anything more than a Zenoah or DA. We do not fly "lawn equipment", these engines may start out as leaf blowers but several engine builders will atest that they share more with the high dollar purpose built counterparts than with unmodified "lawn equipment". Two years ago I even mounted one in a RCPRO Warbird racer and it performed amazingly. The point John is making is that, why do we have multiple care free flight hours while we watch our fellow modelers struggle with durability and performance issues with a much "better quality engine". Evolution engines tend to be a hit and miss for performance and DLEs struggle with durability. All of these engines (with exception of DA and a few others) are made in China. Jheng Feng produces the MB for Macchulloch and Troy-built. and I have seen them survive multiple planes.

geeter

My Feedback: (110)

Motor had a bad ign switch in the plane. Was not the motors fault.

ahicks

My Feedback: (2)

Glad you figured it out geeter. Nice job.

Truckracer

My Feedback: (19)

I have nothing against capt'n and in fact I have read quite a few of his posts over the years that were both informative and interesting. If he were a local flyer, I'm sure I would like him and enjoy his company. So the point here is that I have nothing against the man and in fact, quite the contrary. I don't participate in personal attacks.

But when this thread was started, the first post was more of an editorial than a question and in fact, no specific questions were asked. It could have been considered a troll post in many forums. It was just a statement about how bad some engines are with zero specifics. I responded with quite a few counterpoints and received a response that only stated that he disagreed with me but nothing was introduced that could stimulate a conversation about the subject.

Capt'n, what was your purpose with the original post and where are you when people bring up points of interest? Where is the conversation about the subject? You make inflammatory statements and then just disappear for the most part. Give us some specifics that we can agree with or counter then we can have a conversation about them.

kmeyers

This question was in the first post.

Wow, you guys can sure make simple things tough. I looked up this leaf blower to find some answers we can all use.

25.4 cc block
crank supported on both sides by large bearings. For comparison use the specs of the Zenoah 25.4 cc very similar design and specs.




[TABLE="class: specs, width: 67%"]
[TR]
[TD="class: spec_name"]Recommended Fuel:[/TD]
[TD="class: spec_value"]32:1 Gasoline/Oil Mix[/TD]
[/TR]
[TR]
[TD="class: spec_name"]Benchmark Prop:[/TD]
[TD="class: spec_value"]APC 16 x 8 @ 8,700–8.900 rpm, APC 16 x 8 @ 8,700–8.900 rpm[/TD]
[/TR]
[TR]
[TD="class: spec_name"]Bore:[/TD]
[TD="class: spec_value"]1.34 in (34mm), 1.34 in (34mm)[/TD]
[/TR]
[TR]
[TD="class: spec_name"]Carb Type:[/TD]
[TD="class: spec_value"]Walbro[/TD]
[/TR]
[TR]
[TD="class: spec_name"]Crankshaft Threads:[/TD]
[TD="class: spec_value"]M8 x 1.25[/TD]
[/TR]
[TR]
[TD="class: spec_name"]Cylinder Type:[/TD]
[TD="class: spec_value"]Ringed, Nikasil-plated[/TD]
[/TR]
[TR]
[TD="class: spec_name"]Cylinders:[/TD]
[TD="class: spec_value"]Single[/TD]
[/TR]
[TR]
[TD="class: spec_name"]Displacement:[/TD]
[TD="class: spec_value"]1.55 cu. in. (25.40 cc), 1.55 cu. in. (25.40 cc)[/TD]
[/TR]
[TR]
[TD="class: spec_name"]Engine (Only) Weight:[/TD]
[TD="class: spec_value"]37.3 oz (1.1 kg), 37.3 oz (1.1 kg)[/TD]
[/TR]
[TR]
[TD="class: spec_name"]HP:[/TD]
[TD="class: spec_value"]2.4 hp @ 8900 rpm, 2.4 hp @ 8900 rpm[/TD]
[/TR]
[TR]
[TD="class: spec_name"]Muffler Type:[/TD]
[TD="class: spec_value"]Custom Can[/TD]
[/TR]
[TR]
[TD="class: spec_name"]Prop Range:[/TD]
[TD="class: spec_value"]15 x 8 - 17 x 6[/TD]
[/TR]
[TR]
[TD="class: spec_name"]RPM Range:[/TD]
[TD="class: spec_value"]1,800–10,000[/TD]
[/TR]
[TR]
[TD="class: spec_name"]Stroke:[/TD]
[TD="class: spec_value"]1.10 in (28mm), 1.10 in (28mm)[/TD]
[/TR]
[TR]
[TD="class: spec_name"]Total Weight:[/TD]
[TD="class: spec_value"]46.0 oz (1.3 kg), 46.0 oz (1.3 kg)[/TD]
[/TR]
[/TABLE]

The double supported crank shaft adds weight but rigidity.
This leaf blower (m290) also has two rings which increases drag but reduces top end power. That 46 oz all up weight is just 8 oz lighter then My DLE 55 which swings a 23 x 8 prop at 7400 rpm and can fly a scale 30 lb plane or a 16 lb 3D monster. Also the reason for using the 55 cc example is because when you go down in size, say, 35 cc. The engines weight almost 1 lb less then the leaf blower block.

I have had a Zenoah 20 cc for years. It is a quality engine..but it is heavy for its power.


I would suspect that when you change the demands to the lowest possible weight and the highest possible performance, the longevity will suffer.

Now add in that nobody is going to make and sell something without a profit margin. Also the RC community is full of some of the cheapest guys you can find. What is "Big Money " to one guy is chump change to another.

You end up where we are today. Some engines live in models that will never leave the ground except in someones dreams, so an engine that looks the part is good enough.

I have 3 double supported type RC gas engines because weight is not always an issue. But I have and often use cantilevered style engines when weight and power matter more then longevity. Then I just accept the maintenance and rebuilds.

Truckracer

My Feedback: (19)

I believe the long answers were to support opinions that the Capt'ns contentions were full of crap! Counter points were provided with support examples. Capt'n hasn't been back to provide any further info to support his opinion or to carry on the conversation he started.

av8tor1977

My Feedback: (6)

Well, I will add my "two cents" worth, but only about cantilever cranks and Chinese quality. Cantilever cranks, in a well designed, quality engine, can be totally reliable and safely turn some insane rpm's. I have flown a souped up Homelite 30 cc engine for years now that tachs over 9000 rpm's static. Virtually no problems. I have a friend that regularly flies a hopped up Homelite 25 cc. He refuses to run more than a 15" prop on it, and it tachs 10,000 on the ground. It is probably running well over 11,000 in the air as he is an aggressive flier. In both cases these cantilever crank engines have been flying for years with virtually no problems, and they are not even higher end brands like Stihl and Echo. I don't believe you will ever find this kind of durability with any of the Chinese engines. The only drawback is they weigh a little more. The DLE' s and such have their place due to light weight, easy availability, and low cost, but they aren't what one would really call a "quality" engine I don't think.

This all reminds me of the Korean war and captured Chinese built MIG 15 jets. The engines only had a 50 hour lifespan, after which they had an unfortunate propensity for literally blowing up. Our pilots were afraid to test fly and evaluate the captured enemy planes, because nobody knew if the engine had a "safe" perhaps 25 hours on it, or a potentially lethal 49 hours and 59 minutes!!

AV8TOR

kmeyers

Here is a cantilever crank:



I don't think Homelite uses them.

It is a very common RC type.

w8ye

My Feedback: (16)

The Homelite 25 & 30 both have cantilever cranks

Truckracer

My Feedback: (19)

I believe the Capt'n was trying to say that most if not all the current crop of RC engines and especially the Chinese engines are for the most part ..... JUNK. With that I wholeheartedly disagree. I don't know where he is coming from but my fleet of engines which include both Chinese and American made engines really require very little maintenance and virtually no repair from year to year. Pretty much the same as my mowers, saws, trimmers, etc. I don't see other users having masses of problems at the field either.

This all seems to go back to the Chinese engines and their quality which, for the established brands, has improved by leaps and bounds in the last few years. There are now even a few premium engines from that part of the world and their quality will rival the premium US and German brands. The forums are full of comments from people like the Capt'n that are relaying their thoughts about Chinese quality issues that for the most part were resolved years ago ..... but they keep on harping the same old garbage. Certainly there are some bad engines out there and there always will be but that doesn't make them all bad or create a customer rip off situation.

How to avoid the bad engines? First buy known brands that have a track record, customer support and service and parts availability. Don't buy no name or little heard of brands that may be here today and gone tomorrow. The same advice goes for pretty much any product, not just engines. I rarely if ever buy new products when they appear on the market. When they've been around awhile, are proven and debugged (and well past the beta testing stage), I consider buying if they fit my needs.

w8ye

My Feedback: (16)

Compared with the engines of 20-30 years ago the current Chinese engines are made with fewer machining setups.

Truckracer

My Feedback: (19)

Examples?

w8ye

My Feedback: (16)

"As cast" bearing pockets and cylinder bores.

After nikasil coating they run a flap wheel up through the bore.