Compression

[stoutner]

does anyone have a dyno result on the stock model after broken in?

I just did mine this morning. Throttle open. Engine at 60 degrees.

170, 160, 15, 170

Here is dyno with 1500 miles and all cylinders working.

 

[justinator]

4-5oz of oil in 2000 miles, if that even. Like I said, never measured it to see but hardly even shows on the stick if it went down and 1/2 cup of oil in 2000 miles is nothing, doesnt matter the engine.

 

[blackGt]

Just finished performing a leakdown on the motor and everything seemed fine. I was told by a Yamaha dealership in my area that the readings should be between 195-212.

 

[Len Todd]

So, what specific result did you get on that leakdown?

 

[mulot30th]

my rx1 bon stock engine gets 142-147 on my gauge.

my apex turbo 10-1cr engine get 135-140

 

[GT Mills]

There is a lot of variation on compression testing which largely depends on your test set. I never seen more than 150 PSI on any engine with my test set, no matter what type or make. As for Yamaha I've been flying them since I built the first YG4 in 2012. I've compression tested YG4 RX1 & Apex, YG3 Nytro and YG2 Phazers for aircraft conversions, with 400 mi. - 11,000 mi. in the sled. I just checked my personal '03 RX1 Air Command YG4 gyrocopter yesterday. It has 9000 sled miles and ~100 flight hours on it and flies like a champ, climbs like a homesick angel. It out-climbs everything else every where I go. It starts on the first crank, engine cold, if I've run it within the past week. It uses the expected RX1 amount of oil, the rings have never been upgraded. My test set extension uses an O ring seat and I never tighten it more than finger tight. My numbers yesterday on that stone cold engine that had been sitting overnight were 115 PSI across all four cyl. Once I turn onto the runway, the engine revs to 9000 - 9500 for full WOT climb (prop pitch setting is what limits the RPM on an aircraft, the less pitch the more RPM), then I throttle back to 7500 - 8500 RPMs for the duration of the flight, usually about an hour, sometimes up to 1-1/2 hours before landing, never throttle back below 7500 the whole time.