On May 2013 I have purchased new OS GF40 from Tower Hobbies.
Prior that 4-stroke engine I had good experience with SAITO-14C/17/21/30 and 36.
These Saito engines are marvel pieces of equipment I love so much as they run so well.
I have expected similar experience from well reputation OS brand when they came with the first 4-stroke gas engine . . . and I wasn't disappointed at all . . . until about 6 hours engine in service (excluding one hour for brake-in period).
I have used the highest quality oil mix of 1 to 20 and flown my 2.4 m plane over 20 times until I noticed lost of power.
On closer inspection I have found that exhaust rocker axle is wear out ~40% of its diameter and rocker was loose quite a bit.
http://www3.sympatico.ca/akouzmit/Sa...le_wear_40.jpg
http://vimeo.com/77313341
http://vimeo.com/72599357
I have replace rocker axle once and flown another 10 times and this time I was waiting for lost of power and I noticed it earlier in about 10 flights with new exhaust side rocker and rocker axle.
close inspection shown the same wear on exhaust side rocker axle.
i have replaced it 3-rd time, pre-lubricated axle with special high temperature molybdenum based lubricant and ... Winter came with very cold and windy conditions... Leaving me to wait for spring time....
I have contacted OS support a few times sending them photos and video as evidence of the problem, but the answer didn't satisfy my expectation.
I'd like to ask all other GF40 owners if they noticed anything similar to what I described.
I have to say that engine was used at 100% throttle from 20% to 30% of the time.
The issue is looks to me as a luck of the lubrication at heavily loaded exhaust rocker which is also overheated during engine running at full throttle.
I have to say here that engine is mounted on the plane w/o cowl, thus cooling is just perfect.
This is my "TEST" plane I am using to brake-in new gas engines before they go to more expensive planes:
http://vimeo.com/72161738
As you can see it is fully exposed to air flow, thus cooling is not a problem in my case.
Please, post here your experience with OS GF40 4-stoke gas engine.
Thank you,
Andrei. Humber Valley RC Club.
Toronto, Canada.