kurt2022

My Feedback: (18)

I have an evolution 58, that is 2 1/2 years old and has started running poorly, I first started having problems with 2 deadsticks in flight. So I tried to straighten it out through carb adjustments with no luck. I first changed the ignition with a spare and no change, then swapped carbs and no change! This is what it is doing, I have ran several props on it the heaviest which I have had on it is xoar 24x10 that has been on it for about a year and will only tach at 5,700 now. The second is a mas 24x10 at 5,800 and a top flight 24x10 at 5,850 in which it used to rip not so long ago. Adjusting the high end needle makes no difference in rpm anymore. If I throttle up quickly most of the time it will just stumble and die. I have a good idle. I looked at the spark plug and it is dry and I can't get it to richen up. I pulled the cylinder to change the ring when I noticed there was no cylinder gasket and silicone was used for the gasket, I bought this from horizon hobby this way! I have noticed clean oil on my cylinder and believe it is coming from the case to cylinder rtv silicone gasket. I ordered a cylinder gasket from horizon tonight but can't understand why this engine came from the factory with rtv silicone used instead of a real gasket. Do you think this might be the problem with this engine and could it be sucking air from this rtv silicone leaking and leaning the engine out at higher rpm? This is very weird to not have an actual gasket on it from the factory or is it?

Hope to get some advice on this,

Kurt

pe reivers

I hope Horizon sorted it out for you?
This is not customary in MVVS engines.

Toolman-RCU

My Feedback: (10)

It's possible the gasket blew out completely, mine did that twice. I finally ended up scuffing both surfaces and replaced the gasket and used a bit of RTV. No more problems.

pe reivers

The gasket is 0.15mm thick. Before it blew out completely (without a trace left), the engine would stop accepting idle settings.
Yes, Old type engines had shiny gasket surfaces. Not all that good, as DA also found out. Nowadays MVVS uses a larger feed when planing the mating surfaces. It works out OK.
In old engines with shiny surfaces, a little crosshatching with a small flat file tip works wonders as well.

BTW, I found this gasket blowing problem on several different engines, and on several mating surfaces (carb faces, etc.. Not just cylinder gaskets. Surfaces that must retain gaskets should be flat and rough!
Example:
 High pressure steam pipe flanges have a planing feed of about 1mm! When a steam gasket blows, it's downright dangerous. The high feed provides the flange with bite into the gasket material, and it works well.

jaka

Hi!
What kind of silencer system do you use? Not one of those small aluminum silencers made by other manufacturers I hope?!

Something to compare with: My MVVS 45cc engine turns a Merntz 24x8 wooden prop at 6400-6600rpm.
I use 95okt fuel and 2,5% all syntetic oil.Silencer is the small MVVS cannister silencer witth 25-30cm long header pipe from Krumscheid.

pe reivers

Jan, with all due respect;
what has this to do with lacking or blown out cylinder foot gaskets?

kurt2022

My Feedback: (18)

I had to pull my cowl on my katana to address a muffler issue and found one of my foot gaskets about to blow out on my old faithful 116. I had this problem earlier on my 58. The questions I have are two things, #1 should I go ahead and replace the ring since the cylinder must be removed? #2 the other cylinder looks fine but I wonder if I should go ahead and change the foot gasket and ring for a precaution even if it looks fine?

pe reivers

Just fix the gasket and surfaces. The ring does not have to be removed from the piston.

janch

Hi pilot,

I see very crazy colour of nut. I think engine has been very overheated.

MetallicaJunkie

good observation there Kurt

kurt2022

My Feedback: (18)

just rust, all my evolution cap nuts rust, 3-45's a 58 and my 116, my 80 is to new but I'm sure it will in time. It still swings a xoar 29x10 laminated prop around 6,100-6,200 rpm and the cowl is baffled and the prop shaft casing and spinner back never seem to be more than warm even after sitting a few minutes. The cylinder cooling fins are still shiny and not whitened or pinkish in color. I think the engine is fine, but will pay a little more attention to temperature the next time I fly her.

kurt2022

My Feedback: (18)

This is the plug from the cylinder pictured, I don't think it looks over heated but could be wrong.

kurt2022

My Feedback: (18)

more pics of the engine, i think she is ok, we fly in alot of dust and dirt and wish there was a carb filter. I see some scratches on the piston but the cylinder is smooth and a little carboned up but not alot. I run ALL my evolutions on mobile 1 at 32 to 1 mix.

MetallicaJunkie

i like that connecting rod