Chung Yang vs. Zenoah


Chung Yang versus Zenoah Controversy

We see much controversy on the various RC and Scooter Forums about which is best, the Chung Yang or  the Komatsu Zenoah Engines.  It is much like the ongoing controversies about many products like Ford/Chevrolet, Colt/Winchester, Fram Baldwin, Sony/Panasonic.  We all have our favorites, and it is fun to argue which is best, but in many cases, there is a lot of mis information passed around.  Here are a few facts for everyone to think about when passing judgement or making decisions to purchase.

Where are Chung Yang and Zenoah Engines Made?

Zenoah is a Japanese Company, but their engines are not neccessarily made in Japan.  They are made in more than one country in Asia, most likely, not Japan.  Just like Japanese Cars, and components.  Many cars made in USA, and components all over the world.  With the Japanese names, everyone thinks they are made in Japan….not so.

Chung Yang is a Taiwanese company.  The Chung Yang RC and Scooter engines, at this time are all made under one roof in Taiwan.

Who copied who?

Did Chung Yang copy Zenoah on certain engines?  Not necessarily.  The engines in the 22.5cc to 30cc category have been manufactured in many countries for light industrial and lawn and garden uses all over the world. They also have been, and currently are being manufactured my many different companies. Lets just say the the broadest application may be “weed wackers”, not R. C.  Cars, Boats, Planes etc. They are all clones and no one has been able to remember who made the first engines of this widely used design.  They are kind of like “Small Block Chevrolets”.  Used and made by many companies for many years.

Number One Seller Chung Yang or Zenoah?

Who sells more engines, Chung Yang or Zenoah?  Reliable sources say that Chung Yang sells more engines “Worldwide” than Komatsu Zenoah in the single cylinder 22 to 30cc category.  Chung Yang also has more variations and part numbers of these engines than any other company in this market.  In this sense, Chung Yang is Number One.

About Quality

Regarding quality comparison.  The manufacturing standards of Chung Yang are equal to or in some cases better than Komatsu Zenoah, according to engineering comparisons of manufacturing procedures.  One example is the finishing process used on most of the cylinders.  This is the process of preparing the cylinders before the chrome plating process, and finishing the chrome plating.  The end result is the Chung Yang cylinders have a better finish bore and are more accurately round to promote good ring seal, life and sealing of the rings.  While Zenoah uses the bore, hone, plate, final hone process to finish the cylinders, CY uses the bore, Plate, ID grind for much more consistent cylinder wall finish, and measurable cylinder size and roundness. This procedure leaves a cylinder wall finish that is more compatible to the piston rings. We have compared many CY Cylinders to Zenoah cylinders in the past few years, and will most always find the CY cylinders to have closer tolerances of roundness and taper than brand Z.

Manufacturing Processes

We see discussion on chrome plating problems on engines, but we are not getting the full story.  Chrome plating of cylinders is a very old procedure for a finish bore on a 2 stroke internal combustion engine.  In some applications like Motorcycles & Snowmobiles, it was discontinued back in the 1970’s.  It was originally used, as it was the most economical  manufacturing process to finish the bore in a cylinder.  It remains in the small Chung Yang and Zenoah engines, as it is the most economical way to finish the smaller cylinders.

About Cylinder Chrome Plating Problems

The problem with chrome plated cylinders is that they do not lend them self well to modification of the ports after plating.  When you grind the ports in the cylinder to try and improve the performance, you can create a problem.  In the exhaust port for example one may raise or widen the exhaust port to move the powerband higher in RPM.  In a chrome plated cylinder as it comes from an engine factory, the chrome in the ports extends out of the cylinder bores and into the port a little way.  Porting of the cylinders, breaks this wrapping around of the chrome, and leaves a sharp blunt edge, which gives a place for the ring to grab the chrome and start it to peal from the cylinder.  If it does not peel at first, it grabs small chrome particles that get spread on the cylinder walls.  These small chrome particles are very abrasive, and much harder than steel or aluminum.  Eventually, they will destroy the cylinder, rings and piston.  This is much more likely to happen in a modified engine.  If an engine builder is not experienced on the cause of these problems, they may be improperly porting the cylinders, causing premature engine  failure.  The engine manufacturer is not the one to blame in this case.

End User caused Engine Failure

There are other factors involved in what causes the failures of the chrome cylinders mentioned above.  Oil type, mixture, fuel octane, air filter function and maintenance, and engine rebuilding, just to name a few.  Mistakes are often made with either with choice of oil, or mixture ratio, whether intentional or not.  An often overlooked factor is “ring life”  Piston rings do not last forever.  Single ring pistons have a 40% shorter ring life than 2 ring applications, but single rings are chosen for performance reasons.  How often should you replace the rings?  Probably in 8 hours or less of operation.  Calendar time has no bearing on when engines should be rebuilt.  You should determine how much fuel has been burned by keeping a log, or track the hours of operation.  You can replace the piston and rings to keep the engine fresh and performing at its top level, or run them until the engine and cylinder fails, and blame the engine.  The more RPM’s, the higher the compression an engine has, the shorter the ring life.  To simplify it, modified engines require more frequent maintenance.

3 comments for “Chung Yang vs. Zenoah

  1. January 10, 2017 at 11:02 AM

    Thanks for your input. I can honestly say that I have been involved with the CY Engines since they first manufactured this this engine category. I have used hundreds of them myself, and did not know their was a problem, as we had not experienced that. We have sold many thousand engines and cylinders for CY, not aware of any serious problems. How many failures have you had out of how many engines you have used or worked with? I would like to see some of the cylinders to evaluate them. We are the USA representative for Chung Yang, and once I can see the problem you are talking about and get a first hand look, I will send the cylinders to Chung Yang. If there is a perceived problem in the manufacturing process, perhaps we can help them solve it. Would like to know if it is happening to all cylinders or just some problem applications and sizes. Problems with chrome in plated cylinders has always been an issue, but it shouldn’t happen to often when properly used and maintained. If on in 1000 fails, that may be acceptable. If 1 in 6 fails, that is not acceptable. Would like to have some input as to how long it takes this to happen. How many hours of operation, or how much fuel used would be a good basis to evaluate. Chung Yang is a reputable company with a great factory and broad capability. I have been there several times and seen the operations first hand. They would want any problems with product to be corrected. We just need to pinpoint the problem. I welcome anyone that has had problem with cylinders to send them to us for evaluation, and we will pass the information to CY. If you have questions or would like to return cylinders for evaluation, please email us so we can help resolve this.

  2. May 22, 2017 at 8:42 AM

    Reinigungsarbeiten bei Chung Yang und Zenoah Motoren Im Gelandeeinsatz sollte der Luftfilter nach jeder Tankfullung kontrolliert werden.

  3. May 23, 2017 at 12:42 PM

    Translaton: Cleaning work with Chung Yang and Zenoah engines In the field, the air filter should be checked after each tank filling!
    I certainly agre with that.

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