Lancair-RCU

Hi, Ive started a thread over in YS engines support forum but as general users arent allowed to post in there, can I ask members that are experienced with YS engines to have a read and post here your thoughts or ideas.
The thread is [link=http://www.rcuniverse.com/forum/YS63_FZ_question/m_2039238/tm.htm]here[/link].

Thanks in advance.

Keefer

My Feedback: (2)

I used the YS forum, and the rep there gave excellent advice that worked for my 63. I was having problems similar to yours. Now that I've got mine running well (and no, it wasn't EASY to get there), it runs well - 10.3K RPM on a 12x6. I'm still working the low end needle verrrryyy carefully to get the idle stable at about 2200 RPM.

Razor-RCU

My Feedback: (50)

OK my YS-63FZ spun a 12x7 apc at 11-11.5K and I had it idling below 2K

I was lucky to buy it used from a YS guru-

Richard L.

My Feedback: (24)

10.3K on a 12x6 is way too low of an rpm. It should be swinging well over 11.5K on a 12x6. Mine swings a Graupner 12x7 at 11.5K rpm, and that's 400 rpm on the rich side:



Here is a 20-second video showing the low idle (engine mounted inverted, no onboard glow): [link=http://www.whitetyphoon.com/rc/ys63s/idle.mpg]YS 63 Sweet Idle[/link]

Keefer

My Feedback: (2)

I'm told 10.3K on a 12x6 is fine, and it runs really well that way. I've not heard of too many people getting much more than that. And very few have been able to get theirs to idle below 2000. If 10.3 is too low, there's not much I can do about it. 25% nitro with OS "F" plug, 20% oil blend... That's all she wrote!

Richard L.

My Feedback: (24)

A lot of people are running well over 11K rpm on a 12x7 and even 12x8 prop. My video clearly shows a rock solid idle below 2K rpm, and that's on 20% nitro and OS Type "F" plug.

Lancair-RCU

Should I be worried about the lack of compression hot or cold ? As I wrote in the YS help forum even with the lack of compression I still got 10000+ rpm.

A week or so ago I had it running very reliably, but with an idle around 2200-2300 and top of 10000 with the APC12x7.

Hopefully Ill get to run it again tomorrow afternoon but probably no flying, my nearest field is 30mins away and I need to be no more than about 15 from work when Im on standby. I may just push my luck I wont get a call.

DarZeelon

Keith,


Your engine is giving you very low power.

What fuel are you using?

It is showing 0.94 HP, compared with Richard's 1.31.

Sort out the problem as it will not go away on its own.


The now defunct, smaller .53FZ was clocked by a prominent British engine reviewer at 12,700-13,000, on 12x6 and 12x7 pros, running 30% heli fuel.

The web site where it was printed is no longer accessible.
Does anyone know where it was moved?

Lancair-RCU

So DarZeelon,
By your above comments my engine is also not producing the correct amount of power.
Im running 20% nitro 20% coolpower LHS brewed fuel.

Please some suggestions as to what it may be causing the lack of compression because Im out of ideas. Read my other thread and youll see what Ive done. Ive even pulled the cylinder off "again" to make sure I didnt get the gap in the ring lined up the gaps in the piston head.

Also what tension or torque loading should be applied to the cylinder head bolts ? A friend suggested about 5 foot/ponds was plenty. To gauge this I got a full plastic 2 litre bottle of water, which weighs 2kg (approx 5lbs) placed my allen key (hex head) through the handle, placed one end on the bench and held it with one finger to feel how much pull approx 5lbs had on my finger, then used the same to tighten the bolts. (I hope that made sense)

DarZeelon

Andrew,


There can be several reasons for low compression in four-stroke engines.

Among them are; a worn piston ring, scored cylinder, an excessively large ring-end gap, a bent valve stem not allowing the valve to close completely, mal-adjusted valve clearance (not allowing the valve to close completely), worn/scored valve/valve seats, leaking head gasket, warped head, cracked head...

The easiest to diagnose is the mal-adjusted valve clearance. Just to make sure, re-adjust it to 0.05 mm (0.002").
Adjust each valve clearance with its lifter on the cam base circle; the engine turned exactly 360 degrees, one full turn, from maximum lift.

The least likely is the leaky head gasket, unless the head was tightened on in very unclean conditions.


I cannot, of course, diagnose your engine condition, all the way from Israel, with your engine in far-away Aussie.


I do not want to fail your LHS, but could the fuel you are using be substandard?

Some YS engines tend to metamorphose into 'rabid dogs', when fed 15% nitro and less.
The .53FZ tended to over-heat with it, in that Brit review I wrote about.

If you can get some Byron/Morgan/other proprietary YS 20/20, or 30% heli synthetic fuel, in a sealed container and try it, you will know more.

But if you clearly feel a compression leak, solve it first.

About the amount of torque that should be applied to head bolts, I would believe the number should be in terms of ounce/inches, not in lbs/ft. I tighten evenly, without any torque wrench. Never had a leak.

...I never owned a YS four-stroke either. So, all my knowledge is from many other engines, from playing (a lot) with other people's YSs and from this forum.

Lancair-RCU

Thanks Dar Zeelon,
I feel there is probably a leak in the exhaust valve, even though it shows no obvious signs of one. Valves are adjusted correctly. The valve stem appears to the naked eye to be straight but ? Im stuck now as to why theres a compression leak so how to solve what I dont know where it exists is a problem.
The engine will run up to around 10000rpm with an APC 12x7 but has very poor compression hot or cold so...

The fuel mixed up by my LHS as I watch so its right. The sealed pre mixed varieties locally available here in my part of Australia are far and few between.

Ounce/inches, pounds/foot ? I do them tight but not to the point of being ridiculous.

I am considring sending to the USA for the YSPerformance guys to look at now.

Thanks

djlyon

OK Lancair
I've checked this thread and the thread with Dave and no where have I seen the dumb question and answer. Are you checking the compression with the throttle opened or closed? If closed you are going to get low compression. You can't suck much past a closed valve (throttle) especially on a 4 stroke. I know my engine produces about 10500 to 11000 on a 13/6 APC and a 2200 idle is good for any 4 stroke unless you are in a best idle contest. In that case use a 2 stroke.

Denis

Lancair-RCU

Thanks Denis,
Im checking throttle open or closed, doesnt seem to make much difference.

Dave Shadel has just given me the answer on the other thread," READ THE RUNNING INSTRUCTIONS", now I hadnt thought of that !!!!!!! Thats a big help.

Im going to give it another run this afternoon and then if no real joy Im going to send it to an Australian model A/C engine guru to look at and repair for me. Cheaper to post it within Australia and probably cheaper than paying some guy in the USA to fix it.

Cheers for those who actually replied something constructive to my thread.

Keefer

My Feedback: (2)

DarZeelon - I'm using Coolpower 25% with 2 oz racing castor added. Personally, it seems that most engine RPM posts are inflated - most of my engines run at lower RPMs than those I've seen in posts. I only back off from peak by about 3-400 RPM, and my engines all run well. And YS says the range is 2000 to 12000. Why would I push an engine to go beyond the vendor's specs?

Keith

Richard L.

My Feedback: (24)

The recommended rpm ranges for the YS 63 is between 10.5K and 11.5K rpm, according to YSPerformance.com: [link]http://www.ysperformance.com/html/instructions.htm[/link]

Dave Shadel in the YS Forum said that the YS 63 runs best in the low to mid 11K. Mine peaked out at 11.9K rpm on 20% fuel, so I richened it down to 11.5K rpm for flying.

DarZeelon

Keith,


The two YS.63 I have played with, have shown numbers close to 12,000 on a 12x7.

The numbers you are seeing are more typical of more ordinary four-strokes, like Saito, TT and Magnum, of similar size.

The YS, with its rudimentary supercharging, displays urgency which is unlike other four-strokes.

It is not an easy-going engine that should be propped to spin 9,500-10,500 ground RPM.
It has a far greater revving capability, which must be exploited.


I think Denis' and Richard's engines are closer to par on this RPM issue.

Maybe the CoolPower+ Castor you are using is not as good as 20/20 fuel, or 30% heli.

Check your valve adjustments too.


I don't have a YS to boast about, but I still think you and Andrew, are not getting the performance you paid for, when you selected to buy the YS.

Keefer

My Feedback: (2)

I guess my YS will have to be on par with a Saito or OS - there's not a lot else I'm going to do to work up another thousand RPM. I want to run a 12x6 prop on it - period. That's what suits the plane best. The diaphragm's new, fuel system is tight and holds pressure, new OS "F" plug, 25% fuel, valves are set.

Shame -

Thanks for the input!

Keefer

Vortec

On such a small pushrod it is hard to see if there is any bends in the valve lifters..Try rolling them on a sheet of glass and see if they might be bent..

Thats the way i do V8 ones any way

scole

My Feedback: (5)

Does the low compression have anything to do with the supercharging effect this engine has? Does it have to be low like it is when it is not running, so when the supercharging effect kicks in the compression is just right? My 63 had low compression, but still made tremendous power, 11K on a 12x8 and 14x4.