UP FOR AUCTION IS ANEW OS Max H80 (twin plug, rear drum induction)
This engine has been oiled very well.
Has good compression (90+PSI)
Bearings fell smooth and well oiled for storage.
Engine is complete.
1. Exhaust Baffle and Linkage
2. Acorn Nut
3. Prop Washer and Nut
Has 2 ring piston and needle bearings in the lower end of the connecting rod.
This engine went out of production in the 1970's.
You only need to light up one plug to start it, the second plug will light up by itself when the engine is running. Its double ringed, loop scavenged engine and is a real stump puller with large props. If your engine is new then run it in very rich for about an hour and use castor. The carb assy can be rotated 180 degrees so the carb points up if you invert the engine which can save some hassles lowering the tank. The drum valve (in the photo) has two slots, the one marked with an R lets you set the engine for reverse running. Should run perfectly on zero nitro 20% oil and hand start instantly.
10-15% nitro, propellers 12x6 "Break-in" 12x7, 13x5 to 6, or 14x5 to 6
This engine came with two different types of pistons, a two ring and a single ring. Apparently the connecting rods came in two different configurations as well. Mine all have a needle bearing on the large end of the connecting rod and can be replaced if necessary. The rods are dural aluminum and are made to last. The piston has cir-clips that hold the wrist pin in, no little Teflon plugs here.
This was OS Max's first "Big" engine and it's made very well. There are only two gaskets in the entire engine, one on the carburetor flange and the other is the aluminum head gasket. You can remove the (4) screws on the front of the engine after flying it and lube the bearings, no gasket to worry about (there ain’t none) the case is machined/lapped so well that the fit is such that a gasket isn't needed, no carburetor linkage to fool with (it's on the back). I just rotate the engine until the piston is at the bottom of its stroke and slide the crank pin out of the rod. It easily realigns itself going back in.
This engine uses the OS 704 muffler that is a strap-on type, it doesn't damage the engine in case if you crash the plane like allot of the bolt-on mufflers do. It also has a fuel priming nipple that is aimed at the exhaust port so you can shoot a little fuel in on top of the piston if need be.
The air-bleed carburetor has a brass barrel that will never wear out and is super easy to adjust, I opened the air-bleed hole just a little and my engine ticks over at 1800 rpm idle. It flips starts real easy and with two glow plugs in the head.
"This engine was designed for large R/C model with special purpose such as large R/C scale model or aerial photograph by model aircraft." (Written Verbatim)
This was O.S.’s first “Big” engine and it’s built to last.
If you looking for a utility engine for a big Telemaster , Flying King or Biplane this one would be a good choice. It will swing Big Lumber and run extremely reliably.
The Head has two glow plug holes. You light one plug and the other kicks in and glows once the engine begins to run. Never a dead stick.
Compression should be good to go for 20 years if you use a good quality fuel with 18-20 % oil like Sig Champion.
The connecting rod Big End has needle bearings and can be replaced if need be. I don’t think you’ll be able to wear one out.
Only the early model H-80’s had this two ring piston and needle bearing rod. They later changed them to bronze bush and single ring piston.
Tower sells a Bisson strap on sport muffler that does a better job for flying.
*I do not have the paper work for this engine. If I remember right there was just one sheet and most of the info above was on that sheet.
You can get more info on this engine at
THANK YOU FOR LOOKING"SOLD AS IS - NOT TESTED"
ASK ANY QUESTION BEFORE PLACING YOUR BID , PLEASE SEE MY OTHER AUCTION RUNNING ON EBAY NOW FOR MORE OF THE SAME AND OTHER RELATE...