I have 2 original I got in 1984. Compression is very high, I installed an extra head gasket to lower the compression. in one that kep throwing the prop. Ended up converting it to ignition to get it under control. Can swing big props. I use it on an old phaeton bipe. I've flown a 1/4 scale supercub with it. The second one I ran on glow and it almost rusted solid, I'm trying to get it apart but piston pin won't come out. One of the valve rockers broke in half, I found the surpass rocker is very close and can be used, pushrods are the same too. If I can get it going I'll convert it to gas ignition too, no rust in the one that ran ignition. Setting the valve clearance was never a problem for me, don't know what you're complaining about. Set it and forget it.
I saw one of those for sale over the weekend at a swap. I looked at it and thought, wow, its pre Surpass. Maybe I should have grabbed it. It wasn't what I was looking for. I did find a nice 70 Surpass and did grab that one.
That is the exact engine I have! I am new to glow only about 2 months with them. I have an OS55 Ax, 61FS and this 120 FS. I love tinkering with these on the bench as much as flying them I think. Needing a better test stand, looking at PSP but not wanting to spend an arm and a leg. My upper cover screw is stripped out on my cam cover. I measured them and believe it is a 2.6mm. I think the previous owner crammed a 4/40 in there too. I see what looks like good threads on down past stripped area so ordered some 2.6mm from tower to see if I can get into good threads with longer screw. Thanks again for these videos as I would have no idea how to go at rebuilding these. BTW 1983 was a great year as I was 13! Working on these brings back good memories in general not necessarily about rc but everything in general.
I have ran the 120 a little but it really loads up on low end when I remove glow starter. I can throttle up out of it but the idle seems like it's too rich. When I tweak it leaner it dies and won't restart. I am waiting on more type F glowplugs and bearings. I think I will go through it before I run it anymore, as the one cam bearing looked rusty, but actually felt smooth. I've heard the cage can just rip out if you run them this way. Also do you remove seals on new bearings or run with seals on?
David, I just picked up one of these and was curious where you found the manual? I'm in need of one and have you found any source on parts? Thanks for the video and any help you can provide. Jeff
Where do you get parts for old engines such as these? And when and how do you hone cylinders. With a brake hone or what? What method do you use to clean old engines up. I've read about crok pot-antifreeze method but wanted your opinion. Also I'm in Valdosta, GA what part of FL are you in?
Parts are very hard to find for that engine. I did not replace anything besides the bearings. I NEVER hone a cylinder. If you look through some of my other disassembly videos you will hear and see me mention LA's Totally awesome cleaner ALL the time. That is what I use along with a ultra sonic cleaner from Harbor Frieght. I am in Largo FL
For the older engines my first place to look for parts is eBay. That is the risk when you get these really old engines is spare parts can be nearly impossible to get. Then you have a paperweight. I always research parts availability versus parts that I might need to replace based on the condition BEFORE I ever buy the engine.
I have some parts,measure the push rod tubes. mine are 55.5mm long,5.0 mm diameter.also have original instruction sheets for a for some older os motors.
I will measure my push rod tubes when I disassemble the engine. The OD of my tubes is 5mm. The length that I can measure while assembled is 50mm from lip to lip. That excludes the portion inside the cam gear housing and the valve cover.
So glad I just bought one for $200. Was still in the box with instructions, exhaust, and some tools. Hope I have luck with my first engine I ever own. Hopefully it does good in the airboat haul I got.
Well there really isn't a better answer than that. I have a NIB one and to me it is worth what I paid for it. For me to sell it I have to get exactly what I paid for it. I don't believe in jacking prices up for profit. I mean do an eBay search and see what they are going for. They are getting hard to find NIB and prices can be anywhere from $250++ ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-RAH-KEfhdI4.html
@@dmrcflyr2 I was just messing with you. My appears to be stuck right now, sat for 10 to 12 years. Had it on a Four Star it was wild to say the least. Only a couple hours total on it, but due to use the rotating assembly is stuck. With some careful manipulation I am sure I can free it up.
