I was looking really forward to the new Retrol - Okmo 185 miniature engine to be released and couldn’t wait to order it from EngineDiy.com! I ordered it and it was at my doorstep in 5 days. It arrived packed very safely in a beautifully decorated box, that shows that Okmo & Retrol are proud of this engine… packed in a ‘bulletproof’ foam core specially designed for the 185 engine that assured its safe arrival - no matter how it was handled during the trip from China to me here jn the USA. To me, it really says a lot when a company puts a lot of time and effort into their presentation and packaging… definitely impressed!
I chose the pulley drive version of the 185 for a couple reasons; the poly version gives the owner the choice to start the engine from the PTO pulley, or the rear starting clutch shaft. The pulley version includes two stainless starting shafts for each starting location.
The 185 arrives completely assembled and ready for fuel and three AA batteries that provide power to the mechanical ignition trigger switch, something that I thought was really cool to see on a model engine. Typically our model engines have a hall effect sensor, or a reed switch to trigger the CDI to fire the spark plug. The 185 uses a mechanical switch to trigger the spark, which is a very reliable design that doesn’t burn out.
For fuel I chose to use Coleman camping fuel, with a very small amount of marvel mystery oil for for the break-in period. I premixed my fuel & Marvel oil at around 60:1 which will give the engine a little additional lubrication while the piston ring seat during break in - run in period.
The engine has a very unique and complex oiling system that utilizes a gear type oil pump to pump oil through the crankshaft, the connecting rod and out the wrist pin to ensure lubrication of the piston. Oil also travels up the copper pipes and drops from the valve cover down to the camshaft and tappets ensuring cam lubrication. The piston has a true oil scraper ring that allows the engine to run very clean and not burn oil. i gotta give Mr. Jin big applause here 👏
I filled the crankcase with 6ml of 4 stroke 10W30 oil, installed 3 AA batteries, filled the tank with fuel and was ready to start.
* since this engine has a mechanical ignition switch, it’s absolutely important to make sure the 3 AA batteries are NEW for proper ignition. I initially used three AA batteries that I thought were new and strong and it caused the engine to be very difficult to start and run erraticly. Installing three brand new batteries made the engine start immediately and run perfectly *
I chose to start my engine using the pulley side starting shaft. Starting the 185 from the pulley side requires the cordless drill to be rotated COUNTERCLOCKWISE, where if you use the other starting shaft which is located at the back of the engine, the drill needs to rotate CLOCKWISE.
During my first run of my 185 I ran the engine at 1/2 throttle, positioned a fan to blow directly into the flywheel air inlet, which helped to keep the engine a little cooler during the running in period. The 185 engine likes a bit of throttle when starting, positioning the throttle lever at right at half throttle and a quick finger over the carb air inlet to choke and the engine starts immediately. Right out of the box. It is a very stable and well running machine. I only had to adjust the high-speed needle to richen the fuel mixture and my engine ran solid through the first tank of fuel.
The exhaust sound on the 185 is fantastic! it has a very powerful bark and all through the RPM range. It sounds amazing! I noticed the engine starts and runs even better after 2 full tanks of fuel, and I was able to slightly lean out the mixture which helps to make the engine more responsive to throttle input and low rpm runs.
I am thrilled with my 185 and looking forward to running a centrifugal water pump from the pulley drive soon. The engine has a lot of useable power can tell by the construction that it’s definitely built to last and perform.
OKMO & Retrol have done a phenomenal job in all aspects of their 185. The complex oiling system alone deserves a lot of recognition because it’s not common on many model engines today.
Mr. Jin the 185’s designer & engineer has really raised the standard with his OKMO Model company and looking forward to what he and Retrol creates in the future!!
The Okmo - Retrol 185 is an absolutely fantastic engine that I am very, very proud to own in my collection!
