Greetings,
I have 2 YS.91FZ engines that exhibit the same behaviour......they both load up at low throttle openings (1/8 to 1/4 or so). I have the top end set so it's ~3/400rpm from max and the low end returns immediately to and stays at ~2000 (within 100rpm+-). The regulators on both these engines are set flush with the casing. Do I need to wind the regulators in a little on these, or am I doing something else wrong?

I'm using APC 15x8 props on both, with 20% nitro 20% Klotz, and OS#8 plugs.

Since the regulator controls transition, it sounds like clockwise on the regulator screw about 1/4 turn at a time will fix these issues.

I've been to your country a couple of times and always enjoyed the trip. It's a really cool place!!

Good Flying,
Dave

Thanks Dave....I'll get them out today and see how I go.

Glad you like Aus.....lots of space down here for flying

I got my newest one out this afternoon and tried to get it sorted. I ended up a full turn in on the regulator and it still loads up at 1/4 throttle or so. It's nowhere near as bad as it was though.....it doesn't actually stop anymore if I leave it at 1/4 throttle. It appears that I can only go another 1/2 turn in on the regulator before it tightens up.....I assume that means you're in as far as it can go then? Is it OK to be in a whole turn? I can still get it to run quite rich at the top and it still idles ok, so I assume it's fine?

Sorry I missed it on the first reply, but the OS #8 is probably the whole problem. Try an OS type F. I'm sure you'll find it a whole lot better.

Good Flying,
Dave

DOH! Sorry.....I was talking rubbish.....I *AM* using OS F plugs. I have no idea why I put #8

You might also try stretching the spring in the regulator, and maybe going to a 15x6 prop.
Are you mixing your own fuel?, and if so, are you sure of the quality of the nitro? If the 15x6 helps the problem, it's telling you that the fuel you're using might be a bit wimpy.

Try the prop switch before messing with the spring.

Dave

Yeah, I mix my own fuel. My nitro is VP Racing Fuels stuff, and is fine. I've got several other engines that run fine on it.

I'm finding that the more running I give both of these, the better they're getting. I've been running both of them quite rich at the top. As I gradually lean them out with more running, the better they seem to be getting. I went out again today and ran slightly leaner up top on my older engine......mid-range really started to smooth out. A few more tanks on my newer one and it will be ready to go leaner too. I think that's all it's going to take. With the 15x8 APC props I'm using, I'm getting 9000+ rpm on the ground, while still putting out plenty of smoke (so not too lean)! Strong engines these

Thanks for the help.

Glad to hear that things are working better. The YS engines do require some break-in as you've found. Once the settings stop changing, you'll know that the engine is fully broken in.
The nitro question was based on a lot of experience. There is a wide variety of nitro quality available and some guys are using cut nitro and don't even know. How much are you paying for nitro in Oz? It's still reasonably cheap in the US in 55 gallon drums.

Keep me posted on the progress with the engines. If you want to contact me directly use [email protected].

Good Flying,
Dave

They assure me this stuff is pure nitro.....well, as pure as it can be anyway.

The latest lot of nitro I bought (which turned up yesterday) ended up being A$23.65 per litre. The cost of the nitro itself was quite a bit less than that, but once you add the freight and hazardous goods charge, it gets right up there. The nitro, if I could pick it up myself, would only cost me A$18 per litre. Unfortunately, there's no-one anywhere near where I live that has it, so I have to wear the freight charges I'm working on getting a group of us together to buy a 200 litre drum next time. Should reduce the cost considerably