Dave,

I seems to be having a problem with my YS 63 at high rpm. If I run the engine up to peak I start hearing a clanging that sounds somewhat like the valve train. I have pretty much though this was detenation. When i richen my top end to stop this I have to richen from peak about 700 rpm. My top rpm is 11500 and I have to richen to under 10800 to get this to stop. This is on 30% heli fuel. I have also tried 20% Pro Pattern with added Klotz Technoplate oil. Both times it would have this same problem at high rpm. I have had this engine for about 3 months and have not been able to get it to run reliably. It has had about 2 to 2 1/2 gallons of fuel through it. I am thinking I should send it in for service.

First you ought to check the valve clearance. It should be .003" on both intake and exhaust.

I checked the valve clearences on both the Intake and Exhast and they were .004". The Exhaust rocker seems to have quite abit more side to side play than the Intake rocker arm does when both arms are at rest I noticed.

The side play could be a problem depending on how bad it is. How much would you say in thousandths?

The side play on the Exhaust rocker is .017". The Intake side is around .007"

No big deal, but loosen the set screw and move the rocker shaft over so that the play is the same on both sides.
I don't think this is causing any problems. Maybe it should come see us for a checkup.

I will promptly send it tommorrow. The whole time we have been trying to get the engine to run right we have been suspecting there was a air leak somewhere. But I have done multiple pressure tests on the fuel lines and tank and found none. Do I just send the engine back in the box it came in. This is my first time having to have service on an engine.

Pack it in an outer box. We'll need name, address and daytime phone should we need to contact you.

YS Service
1295 Industrial Court
Gardnerville, NV 89410

Phone 775-782-4562

Sorry for the problem.

I will do. Also, the person that has been helping me with this engine is probably familiar too you. He posts under the name YSMAN here on RCUniverse. Thanks for your time with this problem.

Christopher Belt
Vice President
South Alabama RC Modelers

Dave,

I just received my YS 63 back from the service department today. It seems they replaced the plunger and the piston ring. Since the piston ring was replaced I am thinking I need to run the engine back through the breakin process in the manual. Is this correct? The only fuel I have to break the engine in on is Coolpower 30% heli. Would this be ok or do I need to pick up some YS 20/20?

The 30 heli is just fine. Just keep it rich and ENJOY!

Good Flying,

Dave

Dave,

One thing I have noticed is that the engine seems to be detoniating on the ground a full throttle. But, it does not seems to be in the air. Is this common to the YS 63 engine? The area I live in has a tropical climate. The summers have high heat and humidity usually around 90 to 98 percent. I have been told that this engine tends to run hot on the ground by others. Or should I decrease the percent of nitro I am using? It is coolpower 30% heli. Otherwise the engine seems to be running correctly.

It's very possible that the added cooling in the air is making the difference. You might try dropping the nitro and/or decreasing the prop load a little. Either will make the engine run cooler.

Ok, I will swing by the hobby shop and pick up some YS 20/20 fuel in the morning. Thanks for the swift reply.