Hello everyone! I wanted to take a quick second and address some information about the reduction ratios offered by Vittorazi and why you might choose one over the other. First and foremost, the choice of reduction ratios is only available on the Moster 185 Plus as well as the Moster 185 EFI. The Atom 80, Moster 185 Factory R, and Cosmos 300 are only available with a single reduction drive option and are listed below:
Atom 80 1:3.8
Moster 185 Factory R 1:2.87
Cosmos 300 1:3.04
How to determine your reduction ratio:
Method 1:
The Moster 185 Plus and EFI are available in a 2.68 reduction as well as a 2.87 reduction. If you have an engine already and need to discover which reduction you own, there are two simple methods. The simplest method is to look at the exhaust bracket. Viewed from the back of the paramotor, you will see either a 268 or 287 label in black lettering on a white label. These correspond to the reduction ratio the engine left the factory with. Using this does assume the engine hasn’t been altered because it is a very easy swap to change reductions.
Method 2:
A more definitive way to determine your reduction is to inspect the reduction pulley installed on the engine. Each pulley is stamped with a number that corresponds to the diameter of the pulley in millimeters. The one marked with 130 corresponds with the 2.87 reduction and the pulley marked with 128 is the 2.68 reduction. It is crazy to think the difference is only 2 millimeters!
How to change your reduction:
It is very important to note, if you change your reduction, you also need to change to a propeller that is pitched for that specific reduction.
If you decide you want to mix it up and change your reduction ratio, it’s a very easy swap. First, you will need either MP113 or MP113a. The following instructions are from the Vittorazi maintenance manual which can be found here!
Which reduction ratio to choose:
Given the choice, why choose one reduction over the other? The choice basically boils down to propeller diameter considerations. If you have a paramotor frame large enough to swing a huge 140cm prop and you plan to in now or in the future, the 2.87 is your best choice. At the time of writing this, there is only one Vittorazi approved propeller for the Moster 185 and this one propeller is intended for use with the 2,87 reduction. This makes sense….spinning a longer, higher aspect ratio propeller slower will result in maximum efficiency and the slower rotation will help to limit excess noise. Smaller diameter propellers down to 125cm can certainly be used with the 2.87 reduction and there are several options on the approved list for these short lengths.
If your paramotor frame is 140cm or smaller, like a Parajet Maverick or a Kangook Amaruk, I don’t recommend using a propeller any longer than 130cm. Since the 140cm is not practical, the 2,68 reduction would be my recommendation in this case. My experiences indicate the 2.68 will actually provide just a little more thrust with the 125 and 130cm propellers. In full disclosure, I have not measured the actual thrust numbers with both reductions, so my recommendation is solely based on my experiences.
One thing to be certain of is to pair the correct propeller with the reduction. Even though the propeller will easily bolt on, a 2.68 propeller spins faster and therefore has less pitch. Using a 2.68 propeller on a 2.87 reduction could allow the engine to surpass it’s max RPM limitation. The opposite will happen going the other way. A 2.87 propeller will have a greater pitch, if used on a 2.68 reduction engine, it will not be able to reach its peak power and will put excess stress on the critical components of the engine.
As always, we are here to help! If we can help in any way, please don't hesitate to reach out!
~Bryant