vgless

I recently purchased an RCV 120 that I mounted on a 60 scale Rare Bear. I have little experience with four stroke engines. I started the engine with factory setting and it ran fine except it got hot fast. It burned a hole in the exhaust deflector I had on it and damaged the fiber glass of the fuselage. I richened the low end considerably and got the engine running allitle cooler, however, the highest reading I get on my tachometer is around 524 RPM. The users manual is not very specific about setting up the engine, and I could use some help. I believe I have the low end set at around twelve turns out.

andi3142001

Hello,
first I would get back to factory needle setting as described in the manual.
Second, for the the first break in remove the cowling so you can be shure there is adequate cooling.
What fuel do you use?
Do you have a pic of engine installation and cowling?

regards
Andi

Joe Lott

vgless,

Do as Andi says and get your low end needle back to its factory setting. Go strictly by the manual during the break-in period. The engine will run very rough at first, but will smooth out the more it's run. If you used a silicone exhaust deflector, throw it away. They are useless for these engines. The 4 stroke exhaust is just too hot. Your engine should achieve its best performance after you have run a gallon or so of fuel through it.

If I remember correctly, my first hour of run time was a series of short runs (5 min. or so) each followed by a cool-down period. I ran it at no higher than 3000rpm during this time. It would be better if you have a test stand, because the initial vibration will be tough on your plane. Believe me, you will notice the engine "smoothing out" over time. Your muffler will stop vibrating loose (which will happen alot during the break-in period). Keep an eye on your crankcase vent tube, specifically the color of the oil being ejected from it. At first it will be dark grey-to-black. As the engine components become seated, the oil coming from the tube will clear up.

The low end needle on my 120SP was spot on from the factory, with no adjustment necessary. Mainly, you need to get the engine running smoothly before worrying about the idle. If it is at the factory setting, you will be ok for break-in purposes.

After that initial hour of break-in, I started opening up the throttle for short bursts and set my high end needle 3-4 clicks on the rich side of max rpm. I still ran the engine for maybe 15-20 minute runs, varying the speed from idle to full throttle. BTW, I'm using CoolPower 10%. The engine loves it.

Let us know how you make out.

Joe

vgless

Thanks for the answers, I am using cool power 10%. Did you experience a RPM range around 524 when you first started breaking in the engine???

andi3142001

With the APC 18x12 my 120SP reaches around 5700 rpm. With a Biela 18x12, which has much thicker blades and is much stiffer, I had 5200 rpm. In the air there is no difference in performance.
So I guess your readings are pretty normal (just add a 0 ) but wait with high revolutions til your engine is broken in.

regards
Andi