Product Review Article...
A neat engine reversing kit by MHZ...ideal for twin counter-rotating engine setups in big boats!
MHZ have built a solid reputation supplying quality boats, engines and hardware. This is a new product in their impressive lineup of engine accessories. The engine reversing kit is a simple and effective way to convert a Zenoah engine to reverse rotation for a twin-engine counter-rotating application. Granted twin engine setups require large hulls and might not be for everyone out there, but it has become more common in the past years and if you want counter-rotating engines it can't get any simpler than this!
Traditionally reversing the rotation of an engine is not impossible, but it is a very complex task involving a considerable amount of machine work and engine timing modifications, in many cases beyond the capabilities of most model boat hobbyists. Another issue is often to try and match two engines to perform as close to identical as possible after all the modifications. MHZ have taken a much simpler approach to engine rotation reversing. They actually flip the engine around! That's right, this kit actually converts the flywheel end to the output end and mounts the new pull starter at the old output end. The crankshaft itself is still actually turning in the same direction as originally in respect to the engine, but the output is reversed in relation to the propeller! A very ingenious way to reverse rotation without actually changing ANYTHING inside the engine! It is therefore easy to have 2 matched engines...take two stock engines, reverse one with the MHZ kit, keep the other one stock and you now have two matched counter-rotating engines for your large scale project!
Below are step-by-step pictures of the conversion. I used a stock Zenoah engine and did the entire conversion in about 15 minutes.
Here are the parts included in the kit and some pictures of the instruction sheets supplied. The kit included a coil relocating bracket but I did not install it for this review.
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The stock Zenoah engine |
The pull starter plate installed on output end of stock engine. |
Pull starter adaptor installed on tapered output shaft and secured with the supplied bolt. |
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Spacers for the pull starter in position. |
Pull starter mounted. |
View of the pull starter engaging mechanism. |
A closer look at the pull starter installed (note the spacers) |
Engine mount isolators installed. |
Stock pull starter removed from flywheel end of engine. |
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Stock backplate removed. |
Stock flywheel nut removed. |
Clutch adaptor installed to flywheel. Do not forget to install the new flywheel nut! |
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Clutch backplate installed. |
A closer look...notice the groove at the top to clear the coil. |
Clutch spring washers in place. |
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Clutch shoes with bolts and spacer washers in place. *** important: the clutch shoe assembly must be installed with the arrows pointing in the direction of rotation. Normally you see the arrows when mounted on an engine, but since this engine will be rotating clockwise when viewed at the output, the clutch assembly must be flipped over. The arrows will not be visible with the assembly in place. |
Clutch shoe assembly mounted. |
Clutch bell assembly ready to install...note the spacers. |
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Clutch bell installed. Engine mount isolators installed also. |
Here is a picture of the parts removed from the stock engine. |
As you can see, this kit is very easy to install. The parts are precision machined and everything goes together quite well. All the major parts in the kit we received were anodized. The screws are stainless steel.
As can be seen in the pictures above, the clutch output is an 8mm non tapered shaft. An adaptor will be required to allow for the flexcable installation.
The adaptors are available from MHZ: P/N m-1023/8 (collet) or m-1050/8 (square)
Final thoughts:
This is a must have kit for anyone wanting to build a twin counter-rotating engine boat! It can't get any easier and the engine can easily be converted back to normal operation at any time if desired.
This kit is a great deal considering that you get the reversing kit, a built-in high quality clutch and engine mounts all in one package! Install matching MHZ mounts and clutch on your second engine and you have a perfect pair for the ultimate large scale project! Definitely two thumbs up!
Happy boating!
Price of kit as reviewed: $305.00 USD plus shipping (prices subject to change...confirm pricing with MHZ-USA)
Contact information
MHZ Germany: http://www.mhz-engines.com/