Re: Sick of my YS63 - Will Saito 72 be easier??

The remedies I've tried would take me all afternoon to explain. I have searched and implemented idea from this ng, RCU, and about 4 or 5 other forums. New diaphragm, new reg. spring, valve adjustments, fuel changes, new plug. Nothings clogged up in either needle or the reg, fuels flowing, I know this because it's spraying out the carb and the muffler. The compression is very low (It's always been low, but it seems lower lately), so I'm wondering if the problem is not piston , ring or valve related. I don't know why, it never had a lean run, but I'm out of ideas. I'm going to send it in and see what YS has to say, too bad it's 2 months out of warranty. My thing is, even when running well, you have to STAY ON TOP of this engine, it's finnicky in many ways. You run it dry, and the next day it probably will run just fine, but leave it sitting awhile, well, say a little prayer before you hit the starter. I'm a bit fed up with this, being my first 4-stroke and all. I'm hoping the Saito is reliable and tame and needs little fiddling, or else I'll go OS, but OS is heavy.

YMMV, but I've found this engine to be like a race car, high performance/high maintenance (a bit too high). Some have nothing but good experiences. Some, like me, are pulling their hair out. There was a good stretch where it didn't give me any trouble, I think because I was running it almost every other day (good times!!!), and the power and sound are impressive and it's a looker too. But after you hang around with a super model awhile, you start yearnig for the girl next door again.

Go with the Saito. I have never had one that gave me any grief of any kind and I have had them from .52 - 1.50
I'd send YS to the factory and tell them all your troubles. It's a very expensive engine. Hopefully their service will be commensurate with the price. Let us know how it turns out.

That's the nature of the beast. When they run right, they run great. When they don't run right, they're a PITA.
Sounds like you need to reward yourself for all your hassles. Try a Webra .52 AAR Heli some day. Everyone should have a good 2 stroke for grins and giggles and as a backup. If your wife gives you that look, I'll put in a good word for you. :-)
"Uday and Qasay...good day!" -=Neil Cavuto=-
Bob

Get an OS 70 and never look back.
Rein

Well, I have lots of 2 strokes, they are a joy to run, I guess I'm spoiled. I would like a 4-stroke or 2 though, and I'll be honest, it's the sound that I really like. The torque is nice too.

They have had problems with the rings on that motor,send it to performance specialities and they will fix it if it's not too old for free..........

The Saito .72 I had was a pure delight in exactly the way you are yearning for, Frank.
Ed Cregger

As a veteran 2-stroke junkie, last year I decided to try a change of pace and bought a Saito .72 to put in my Pizazz. I based my decision on the good reports I had heard about it.
I have had absolutely zero trouble with it, so as this is my first 4C I' think that says a lot. I read the instructions, recalled whatever I had read or heard about tuning 4C's, and fired it up. No sweat. New flying day, I back off the main 1/2 a turn or so, fire it up, retune the main with the nose up, and go. It provides just slightly less oomph than an OS .46 in vertical lines, but I absolutely love the sound and throttle response, and it will hover the Pizazz at perhaps 90% throttle (with full tank, 6 std servos and 600 mAh pack - I should weigh it sometime to be more objective). I spend a lot of time at about 1/3 throttle down low farting around, and often launch underhand from behind the canopy at about a 45 degree elevation angle. I run 15% in normal conditions and 20% on hotter humid days if I remember to. Used 12-7 and 13-6 APC's, prefer the 13-6 for this aircraft.
So my humble opinion is that it is a fine quality, user friendly 4C engine. It may very well be what you're looking for based on your experience.
Mike D MAAC 36930

A great running 4 stoke is awesome alright. Trouble is, I have seen a ratio of about 1 out of 3 that's a pain in the posterior. Sometimes I think they try to commit suicide with all the vibration.
Best of luck Frank.
Bob

That's my suspicion too. Seems like the same problems that occur with the 91FZ. There is a gas port mod that they do that is supposed to fix it. Blurting out from the edge of my imagination I believe this consists of drilling holes down from the top of the piston to the ring land behind the ring so that the ring is expanded by the expanding gasses on the power stroke. I understand that grooves may be used in some cases. Sounds like a poor man's Dykes ring. One would conclude that there gets to be ring bypass after some use even though the parts aren't considered worn out. Perhaps the ring is low tension to squeeze out a bit more power but is too close to the edge of reliability. Don't quote me. This is only my musing.
I posted to RCU on this because of similar problems with my 91FZ. Dave Shadel suggested it needed the mod but didn't give the details. It's on the way to Performance Products now.

Either Saito or OS 72s will be good to you if you are good to them.
John VB

Frank, Sorry to hear about your problems with your YS. I've got two YS53's in a twin, and never had a hint of trouble or even had one engine flame out during a flight. Seeing as you are getting dirt in the regulator, do you have a good fuel filter between the fuel tank and the carb? Is the fuel fill between the filter and the fuel tank? I'll offer to fix it free of charge if you are not happy with it. I do almost all the engine fixes and rebuilds for our club. Moot

FWIW, I have a filter in the clunk pick-up in my fuel jar, Helps eliminate some problems even before it gets to the tank. Andy
We can make a box of wood.....FLY!!

I'd be cautious about concluding there was dirt obstructing the plunger after following that false path myself. This sounds very much like ring bypass screwing up the regulator as is known to happen in early 91FZ engines. I would talk to Performance Products and see what they have to say.
John Hawkins - From Canada's Atlantic Coast

I have two .91s, an AC and an FZ. Neither one ever gave me any problems that I didn't cause! The AC has many years of running on it and the FZ is a little over a year old. Very little difference in running or tuning. I have also seen dozens of these run with no problems. My unknowing guess is a defective part.
-- Paul McIntosh Desert Sky Model Aviation
performance

Paul, I also have two 91AC's that run perfectly, however I also have a third 91FZ that doesn't. None of the goodness from the other two seems to have rubbed off on it and it has stubbornly resisted all the charm I could lay on it. And yes, I think you are right - there is something defective. Dave Shadel came up with the gas port mod to address problems that share the same symptoms as the ones discussed. YS then used the mod as OEM. This is not to say that this is the answer to the problems with the 63 but it certainly suggests it is worth exploring. I sent mine to Performance Products after trying every suggested fix in the three closest galaxies without success.
There is an additional problem that a number of people have had with leaking air boxes on the 91. I had that one too. Holding a micro light inside the box clearly revealed the problem. Don't know if that applies to the 63 though. I say let the shop have a go at it.
John Hawkins - From Canada's Atlantic Coast