asmund

I have finally got my big fourstroke airborne, it is powering my new Harrier 100 (90) and runs incredible strong. I tached it today after having used it on a couple of flying sessions. On MenzS 18-6 it tached 9000 rpm at peak, flying at 8800 rpm, this was confirmed on two different tachs and readings was stable and consistent.
I think this performance is ahead of the Saito 180.
Fuel used is a Norwegian helimix blend of 15% nitro ,15% synth

The engine will not idle reliably below 2500 rpm on startup and tuning on the ground, but when I come in for landing after 10 mins of flying it idles so low it barely pops around. I am very happy with this engine and it hovers my big Harrier around on the deck with 100% reliability (no pump or anything) and pulls 4 kilos from standstill to fast vertical in the blink of an eye.

Best of all it runs smooth and sips the fuel[8D]

togatoga

My Feedback: (42)

A very good engine for the price.I am running it in a rascal110 with a 17x8apc. Idles very well and great exhaust note!

XJet

As for your idle, there can be two reasons for this...

The first reason is that most 4-strokes take a lot longer to warm up than their 2-stroke cousins and, until they're warm, they won't idle so good.

Second (and one that's often overlooked by many) is that the fuel head of a full tank is often a lot higher than that of a (near) empty tank. This will cause some engines to run very rich at idle when the tank is full and hence the fire goes out.

To check and see which of these (if not both) are your problem. Once you land your plane (with the nice low idle) *don't* refuel it but do let it cool down. Then restart it and see if the idle is nice and low.

If it *is* low with the near-empty tank then fuel-head is your problem. If it's still unreliable then it's just a case of warming the engine up more when you start or using a hotter plug/fuel.

asmund

Thanks I`ll try that[)]

togatoga

My Feedback: (42)

Hi Asmund, can we have a pic of that velocity stack and how did you make it.I'm thinking of fitting one myself. Later on, I'm thinking also of converting to spark ignition.

yallaair

After asmund got this strong RPM reading, I had to test my ASP 180 fs, just to compare. Found that a plausible reason for the sluggish idle is the tank elevation. Tests in my test stand confirmed this. However, my 180 fs is not able to perform nearly as strong as his. My RPM reading is 700 RPM behind. With the same fuel, plug, headshim removed, drilled muffler... Can it be that the tolerances in the production line is so bad that you must be lucky to get "a good one"???

asmund

I have a camera now, but I still have absolutely no clue as how to download pictures and make them appear on this forum. The stack isn`t much really, it is just a piece of plastic electrician pipe at almost the same inner diameter as the outside of the carb venturi. I heated the end of it to soften it and slid it down on the carb venturi so it got to shape. After it had cooled I pulled it off and degreased the mating surfaces and then superglued it to the carb. It is about an inch long. The stach isn`t very pretty, but it doesn`t show inside the cowl anyway and it seems to work great. I could have heated the other end of it too and made a trumpet shape on it but I forgot it in the hurry I was in.