BRIAN95

Hi Troy,

Hope the competitions are going good for you.

Fuel : CP 30%
Plug: OS type F
Prop: APC 12*6
Tappets: 0.003 inches
the engine is very reliable

My YS 63 FZS has approx. 374 flights or 62 running hours. I feel that lately it has begun to lose some of it's power around mid throttle and at full throttle. ( I also own a brand new 63 FZs so the comparison is simple ). From previous posts I understand that this is normal and that the engine needs to have a ring change and be examined by Richard from the Service department. My question is can I run it like this till the winter before sending it in or can this cause damage and I should send it right away?

Thanks in advance
Brian

Troy Newman

Normally the engines will start to loose power at about 250-350 flights and usually this is time for a new ring. While you are in there new bearings, gaskets and O-rings is always a good idea as well.

Can you continue to run it...yes you can. I would say that there could be other wear issues that can creep up on you. Worn connecting rod, or rear disc valve. Bearings, and other issues that can present a issue. As the engines get more time on them these parts begin to wear on any any engine. If left uncorrected these issues can cause major failures.

Will it be Ok for another 20 flights, 50 flights, 100 flights. More than likely it will be. However the risk of a major failure goes up. Example if you fly off grass then you are way past time for a bearing change. A bearing failure can result is major expensive repairs. If you fly off pavement then I would not be too worried about the bearings if they feel smooth.

Lots of things go into it. I don't recommend running them until they stop then fixing the parts. Its just like your car. Preventive care, and an occasional checkup is good and prevents a major failure.

Typically when power falls off from a worn ring it will start slowly and by the time you notice it it will be falling fast. Like within 20-30 flights of the time you notice it the engine will just not run reliably at all.

Troy Newman
Team YS

BRIAN95

Thanks for the quick and thorough answer. I will have the engine serviced before running.
Why is the grass field harmful for the bearings?

Cheers
Brian

Troy Newman

When takeoff and landing on grass small bits of dirt and debris will be injested and will damage the bearings.

dirt, grit, sand, grass clippings, grass seeds and so on.

Troy Newman
Team YS