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Moster 185 classic


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Anyone has experience with the moster 185 classic? 

Local guy is selling one with broken crankshaft very cheap. I'm trying to determine if it's worth fixing with around 800$ of parts or buying a moster silent for 4000$ and swapping it. The ask price is 1500 with sd2 frame, two propellers, seat, new cylinder head and few other parts. He says the engine has 120 hours and the pull starter rope wrapped around the flywheel and broke the crank shaft for some reason. He came down with reduced rpm and landed safely.

do propellers fits on new moster's?

is the mount pattern the same as the new moster's?

Is reliability an issue with old moster's?


i am currently flying a sd1 frame with a ros 125 which i quite like but lacks power. maybe the rings are done on my ros 125 i will be checking compression when i receive my tester.



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Bought the engine after speaking with my instructor friend and Eric Sigier from AirProParamoteur.


My guess is that the rings and piston are good, the magnetic flywheel broke off so that would explain the drop in rpm. I'll start by tearing it down then just changing crankcase bearings, seals and crankshaft. Parts are in stock here


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picked up the engine yesterday. Teared it down today so now i am waiting on parts. Overall it's in better shape than anticipated. i think the previous owner heated the crankshaft  to pull the starter pulley assembly (not needed) which caused the faillure.

main features

2x new Carabiners

Apco universal seat in good shape 

15 liter gas tank 

solid double hoop frame 

3  pull starter assembly

brand new cylinder head 

gaskets for carb, exhaust and cylinder head

brand  new carbon prop 130cm and wood prop 125cm


pictures will follow





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engine  a bit dirty, exhaust welded twice 



broken end of crankshaft


Piston is melted, needs replacement


Thankfully cylinder is in good shape, very smooth


removed carb and airbox


Removed engine from frame and detached carter support. Then split the case


Finally removed the big pulley, i will replace the bearings




So far everything is good exept for the crankshaft and piston. I will replace all seals and bearings. I will use permatex ultra grey to seal the case back together. 


Will post videos eventually

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  • 2 weeks later...

Might get the parts next week. they ordered a crankshaft last week they had just changed one on another machine.

started to clean up the frame and redo the fuel lines. checked the carb and it looks like it was overhauled recently. I will reset the carb to factory settings because it was obviously not running right.



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Parts arrived Friday so here's the reassembly. I left out some parts as it was the same as the dissassembly. I set the squish to 1.5mm using my thinest gasket and use loctite on pretty much every bolt.

Cleaned crank halves 


Heating crank halves to 220F


New Bearings for the crank


The bearings dropped right in (shown in video. Now putting the new crankshaft in.


Closed the crank halves. used permatex ultragrey to seal them. Torqued to 10 Nm and used loctite.


Installed carter support and crank back on the frame for easier reassembly. Carter support sealed with permatex ultra grey and torqued to 10nm with loctite. Seals pressed in (shown in video)


Installed flywheel, pinion pulley and big pulley. I replaced big pulley bearings following scout aviation tutorial. Flywheel torqued to 40nm


Carburetor  and reed valve back on.  Torqued reed valve to 10nm and carburetor not torqued only loctite .


Redid the whole fuel system with the custom primer bulb and blow tube


Work area in my parents basement


Reinstalled muffler,silencer and airbox



Installed prop and gave the engine its first pull, started right up.


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