OS 50 64th flight overhaul

[tauscnc]

Hey guys,

64 full flights on my raptor 50 and 4 gallons though the OS 50 started to run a bit rough. No prob, I figured it was the glow plug so I took it out. I found a rather large hard deposit in the plug...O no, is the OS eating the bearings?

I thought some of you would find this interesting and maybe I can get some viewpoints from the engine experts.


Here is a picture of the crankshaft. The main thing to note here is I DID NOT grind the web off as many have. I instead lathed about .07mm off the web to give a little more space for the "oil drainage." As you can see I have a ring of rust on that part I lathed. Interesting.


Now here is the pic of the rear bearing. Also rust mostly on the part that contacts the crank.


Here is a picture of the crank after clean up. The rust was very easy to clean off. I also decided to grind off the web, but only about 90% of it. Don't ask why, no reason really. The crank looks almost new.



Here is a picture after some paper towel was rubbed on the rear bearing. Rather clean. Again, the rust came off very easily.

I found no metal or nicks on the piston. The rear bearing is very smooth with no gritty spots. Fuel used to break in was coolpower 15% and then after about 1/2 gallon I switched over to wildcat 15%. OS 8 plug and the engine is ran dry after each day.

taus
www.cuttingedgecnc.com

[WillJames]

Looks like the problem was the SSL being used. Your links start with https:// I removed the s and now they start with http:// and they work.

Interesting...

[tauscnc]

Hey baja170,

Good catch 8) I edited the post also to go with the pics. HOWEVER, when I click on the link that is in my email address it goes to helifreak but says

"The topic or post you requested does not exist"

If I come staight here then it works.

Thanks again!
taus

[tauscnc]

More info:

I removed .07mm off the entire crank as the first picture shows. This was done before the engine was ever run. It was then broken in and not touched for 64 "3D" flights. The rust ring is the part of the crank I removed. The reason I did this was many years ago when the OS 61 SXH came out it had the same web "problem." Some were removing the web another guys I spoke who is a top flier today and also tuned engines said they where shaving off some of the material instead. He told me I could send in my 61 to him and he would do it. Not having a clue who he was back then, I declined and with apprehension, ground off the web. The OS 61 SXH ran fine from what I could make of it. Now, since I have the lathe, I figured lets try that, something else that we could all learn from. The engine was broken in on coolpower 15% and then I discovered wildcat 15% and noted an improvement in power. I also liked that fact that it had the 18% oil OS wants. Another friend asked about the time when this engine was bought and used. I bought it in Nov.- Dec of last year and broke it in and flew through out the entire winter. The coldest days where around 23-25 degrees F. One theory is the extreme weather changes (car to outside back to car) caused a lot of moisture to be sucked into the engine causing premature rust. Another idea is I cut off the protective rust coating. That sounds good too! Now my question would be, for the guys that are grinding away the web, are you showing this same rust issue?

I plan to try her out today, break her in on one tank and then get back to flying. If things don’t work out I will purchase another crank, etc. I will also try to keep a close watch on my flights and open her up on flight 120ish to see if the rust is back with the summer months.

taus
www.cuttingedgecnc.com