gfyss

My Feedback: (14)

Hi all,

After many years of 2-strokes, I decided to try a 4-stroke. I am now the proud owner of a YS-63s.

The situation:

YS-63s with 11x8 prop. Fuel is 5% nitro with 15% full synthetic oil. I setup the low and mid range per the instructions and everything is fine up to about 2/3-3/4 throttle. Above that, the engine sounds like it's bogging down and I hear what I would swear was metal-on-metal "clacking" sounds. I pulled out the tach and played with the high needle and found a "peak" at 10600 rpm, but still get odd behavior (surges, sags, metal sounds) at full throttle. I've also reset the gaps on the valves using a piece of paper as a gauge. I've run at least 2 gallons through it.

Of possible note, there is very little exhaust smoke until about 2/3 throttle with a steady increase in density up to full throttle at the "peak" setting. If I lean it one click further, the engine looses power and makes more and louder "clacking" sounds. richening even one click seems to sap power from the whole throttle range above 1/4 stick.

Is there anything I should check?
Is it considered "broken-in" yet?
Is the high needle supposed to be this sensitive?

Any help, hints, or commiserations are appreciated.

Thanks!

broke_n_bummin

Probably don't have enough prop. Try a 12X7 or maybe a 13X4. Is the engine inverted? What plug are you using? Don't use paper for a gauge. Pick up a set of feeler gauges for $1 at Autozone or somewhere. Paper's not real consistant, especially when it gets wet. What's the book say ?? .002 to .004? Set 'em both at .003 and forget about them. If you have 2 gallons through it, and it was broken in per the manual, it's as broke in as it's going to get.

broke_n_bummin

One more thing. 4 strokes only fire every other revolution. You might want to try some 10% or 15% nitro. I run 20 / 20 in mine. Some run 30% heli fuel, but I wouldn't recommend that. Try a bigger prop and put your valve lash where it's s'posta be and see what happens.

Jim Schwagle

My Feedback: (1)

The fuel is significantly under "nitro'd", under oiled and the engine is under propped. YS engines run best with 20 - 30% nitro (Hence the name 20/20 YS Fuel). Less than that and they become significantly harder to tune and run. The fuel should be a minimum of 20% oil, preferably all synthetic. Prop it to run 11,000 to 11,500 on this fuel and it will be propped correctly (most people seem to find that it means 12X8 or 13X6 APC, the main thing, though is to make the engine run in the right range). Reread the instructions, it mentions all of this. YS engines generally cannot be fueled and tuned the same as others. One other thing, after reading the other posts, use an OS F plug.

Edit for addition.

gfyss

My Feedback: (14)

I'm using an OS F plug and the engine is mounted inverted. I can't put a larger diameter prop on due to ground clearance, but I do have a 2-blade 11x9 and a 3-blade 11x7 that I could try. I live in Europe where nitro is horrendously expensive, but am returning to the states in August. I have some Klotz synthetic oil I could add. The instructions say the valve gap should be 0.1mm which is a hair under .004 inches. I'll see what I can find to get the distance correct.

This has definitely been a learning experience.

rlipsett

ys engines put out smoke when they are running correctly if they are not then the plane is running too lean and they are finicky about what they like too eat but that is there charm

opjose

Like he said... don't be afraid of smoke.

Better to run it rich than lean.

Remember that if you are at the point that 1-2 clicks makes THAT much difference in power, you want to turn it rich so that as you've said it seems to lose power at the 1 click rich setting, that is the way you WANT to run it!

In the air the engine will lean out so you'll be right on the money.

Also it takes a while for the engine to develop full power. Usually a couple of gallons of fuel are required.

Don't be surprized if it seems a little underpowered at first.

Jim Schwagle

My Feedback: (1)

I would re-set the valves, hi and lo needles and pressure regulator to factory settings, try out the YS 20/20 when you return to the States (It's going to make a BIG difference, I've never had a YS engine that didn't run nicely right from the start) and try props that put it in the right RPM range. If you bought your engine overseas I'm not sure of the information included with your engine. Tuning instructions from the US importer can be found here...

http://www.yspartsandservice.com/pdf/FZ63S.pdf

Also you can try the YS forum here on RCUniverse. There's a great deal of information about setting up YS engines.