Glad to see this run much better than before. Much better run which was great to see. I still think there is some more adjustment to the low speed (lean) as there was still a detectable drop in revs after the glow igniter was removed? Totally agree with the YS comments. Those engines just explode from idle to full power. I just read page 3 of the manual and it says "When new, 2 to 3 minutes of running time will be required for the pump and regulator to begin functioning properly. During this period you may not be able to get full throttle mixture rich enough. In this case just run the engine at approx. 3/4 throttle a little longer." This may explain why max power is achieved at 3/4 with respect to the throttle barrel notches? Perhaps it needs 3 minutes idle time for the pump and regulator to prime correctly and purge any air that may be interfering with efficient suction? Just some thoughts... An interesting and entertaining video David! Especially feeding the tach into the prop! haha I had a good chuckle. Prop 1, tach 0! It's times like these that you're glad you used a turnigy tach!

I have 2 of these and highly recommend them. The pump system works very well and they definitely suck the tank dry, they run just as well invente. They also run without the muffler. As I said I highly recommend them

your tach hitting the prop made me remember a few years ago,i was running a new magnum fs120. my uncle was looking at the motor and i told him not to stand so close to the prop. well i turned my head for a second,and it happened. he stuck his finger in the front of the prop. found pieces of finger tip on my run table.off to the ER we went.

Hello David . I`ve been away from your channel for a while , man am I glad to see you back doing engine videos again . I grew up with my Dad scratch building planes ,covering them with silkspan , and putting k&b green head 40`s in them . I love your archives , I go nuts watching engines run that I`ve had or friends have run in their planes . It can be a real trip down memory lane for me . Great to see you again and you are greatly appreciated by many . Thank you .

Pretty decent run OS engines are usually awesome runners right out of the box, but diaphrgram pumped engines tend to need more time to run in, maybe pump and carb regulator are part of the run in process, once fully broken in they are rock solid reliable thats what i found with pumped OS engines.

Good to see a better run from the motor How do the o rings inside the carb look? I found an improvement in throttling when I swapped rings in a os 46 sfp carb. Went from sluggish throttle to more usual pickup. Plus it was real sensitive to needle and idle settings until new ones installed. Similar diaphragm type pump. Maybe your engine has been sitting dry for a while and they have gone hard? You seen to have similar sorts of mixture issues getting the carb tuned. Having to limit to 80pc throttle ain't right.

Good to see you get a good run out of this engine Davod.

Had a friend who had a new in the box os 70 f/s ultimate and had nothing but problems with it . He sent it back to os , they couldn't fix it so they gave him credit on a another different new engine ! That was a Good run , but I'm surprised the tachometer doesn't have wings for I would have thrown it ! Keep up the good work !

Thanks David, I wonder if this engine would run better without muffler. As you know I run this engine on a 1/4 space walker with exact settings that you mentioned and it’s very reliable. Cheers 👍🏽

The -155P may be a different engine but when my OS FS 91-Pump was operating OK, it would run without any issues till the tank ran dry. Nowadays I am having problems and I think it has to do with the regulator and/or pump perhaps not working as well as they once did. One other comment. From the sound of the engine, it seemed the propeller was taxing the engine too much. Have you tried a smaller prop or perhaps a 16 in prop with a finer pitch? Sorry about the Turnigy incident. I should "accidentally" do the same to mine as this tach gets quite erratic at times and I really want to toss it ...

What about the os 120 with roots supercharger

Ha! Great vid Dave. Those turnigy tachs are rubbish!! I’ve chased those numbers up and down also. More of a guide then accurate. Anyway ... good to see another run mate. Sounds sweet! (Although Teddy didn’t care for it much !!🐈)

Tiger looks like a great cat.