When its time for a rebuild has a lot to do with the conditions that its run in.

If you are flying off a grass field or a dirt field then it might be time to get new bearings at about 15-20 gallons of fuel. It will depend. As for engine performance 15 gallons is not very much. If its run in a dirty environment like I mentioned about time for a new ring too. if it has been flown in very clean environments then its not time yet.

The worst the flying conditions the more often you should replace the bearings and or perhaps the ring.

To give a rough estimate. I run the 160 and 170 engines in my pattern models. I burn 30% heli fuel and using a 20 oz tank I likely get around 8 flights 12-15mins each out of a gallon of fuel. 15 gallons is around 100-120 flights. On my engine....I usually will start to look at new bearings and new ring around 250-300flights.

usually the engine starts to loose some power at this point, and the ring is the important part of the rebuild for performance. While it is already taken apart I usually stick new bearings in it. However I have done the bearing thing every other time and it has been fine too. So 500-600flights on a set of bearings is not a problem if the engine is carefully maintained. I fly on pavement 90% of the time and also keep good track of the engine and its performance. I also use a very good fuel that helps protect the engine.

The next problem is time. The engine is 3 years old, and the bearings are likely fine, however that is not much run time in 3 years. If it is taken care of properly and a good fuel run through ti then 3 years is not an issue, however it could mean it is getting close to time for new bearings. The bearings can get rusty if you fuel of choice is not good, or the conditions the engine is stored in have extreme temperature changes and or high humidity.


I would not consider a 15 gallon engine low time being its a 3year old engine, however its not a high time engine either.

I know this didn't answer the question you wanted to know. Is the engine still good? It should be if it was taken care of. A rebuild new ring is about $20 new rear bearing is about $20 and the front bearing is about $15. Misc gaskets and so on and you are looking at $60-80 worth of parts to make it like new assuming there are not other issues. On the large 140 and 160 engines this is nothing compared to a new engine as they will perform like new. On a 63 thought is gets to be a larger amount in comparison to the total cost of the engine.

It all depends on how you look at it and what your needs are. Can you do the work yourself? That is another cost to consider. I think YS Parts and Service charges around $35 for the labor but I'm not sure about that. I usually do my own repairs.

Troy Newman
Team YS

In most conditions 15 gallons is not close to the time to rebuild.