Gregg Uhlendorf

This is a great thread. I have gathered a lot of valuable knowledge of Saito engines here. Perhaps the great Saito gurus can clear up some things for me.

My FA-72 (ca. 2002, rev G, no choke) chewed and partially blew the intake manifold-head o-ring causing an in flight flame out. From what I have read here, this was an inevitable eventuality for a 72 and I will try the published remedies. It may have been the result of a lean run overheating the seal when the pressure tap gnawed itself out of an older style machined muffler on a prior flight (hard to believe they designed the tap to thread with half the diameter in, the other half out, of the too short baffle/end cap threads).

I ordered a carb gasket set (8091B) to replace the manifold seals, and an engine gasket set (7232A) to have on hand.


In the carb kit, I find the 2 intake o-rings (one labeled "Viton" assumed to be the head end?) and metal compression washer. I also find some additional items that I do not see in the manual's exploded view (the pictures in both old and new manuals appear to be down-level, incomplete, or of a different engine model):

1 o-ring ~11mm x 8mm x 1.5mm (same as the carb-intake manifold seal)
1 o-ring ~5mm x 2mm x 1.5mm
1 o-ring ~5mm x 4mm x 0.5mm
1 o-ring ~3mm x 2mm x 0.5mm (in the Viton bag)
1 white plastic washer about the size of the intake seals.


In the engine kit, I recognize the cam and rocker cover gaskets as well as another set of intake manifold seals (but no metal washer). The backplate gasket shown in the manual is not included. Is it not used on models with plastic backplates? There is also yet another unidentified seal:

1 o-ring ~4mm x 3mm x 0.5mm


So, my questions are:

What are these extra parts I have listed for?
Why no backplate gasket as shown in the documentation?
Are there more up to date/more complete exploded views or documentation available somewhere?

William Robison

My Feedback: (3)

Gregg:

I'll try not to miss anything here, and on behalf of RCU thanks for the nice words.

You have one of the early FA-72 engines, with the "Springy" back plate. The wonder is that it ran for as long as it did without eating the intake seal. The new ones look the same, but they are much stiffer. You can order a new one from Horizon, you'll get the stiffer one.

The failure of the muffler pressure tap is rare, but it happens. If you have access to a TIG welder you can build up a nubbin, then drill and tap it for better thread engagement.

I have never gotten a Saito gasket set without having extra bits in it, I just save them for whatever need comes to hand.

A couple you mention though - the white ring is Teflon, it is used to seal the choke plate when one is fitted, it goes in the groove on the outside of the carb, the choke slider holds it in place, There are two places for the tiny ones, inside the needle valve as an air seal, and on the front end of the axle the cam turns on. The Viton seal? Who knows? I've never seen one as OEM, and the plastic back plate can be sealed with a smear of RTV at assembly.

Hope I got it all.

Bill.

William Robison

My Feedback: (3)

Gregg:

Forgot to mention - I put you in as member number 206 in Club Saito.

Bill.

Hobbsy

My Feedback: (102)

WR, I did a little experiment today with my old Saito High Compression 1.50, I ran it on 5% nitro fuel, much to my surprise there is very little difference between 5% and 10% operation. With a Mejzlik 16x8 and a Fox Miracle Plug it ran 8,890 rpm on the 5% fuel, a distict advantage I think is that I can lean it 3 clicks lean of peak and it does not kick the prop off, it only slows down a little. On 15% nitro it will kick the prop off if it even thinks you're going 1 click lean of peak. The lube is 20% castor.

proptop

My Feedback: (8)

Let me ask you guys for your opinions...

Do you REALLY think that going to 20-30% nitro is worth it?

I have an old, high compression .80 and I noticed the same thing as hobbsy...(I mean Torque Wrench )

I also have a 1.00 that I've always used 15% in...
I have a gallon of 30% CP that I added 4oz. of castor to, but the weather in central NY ain't conducive to flyin' lately, so I'll wait 'n see until spring.

P.S. Nice car T-W
I had a '67 Galaxie 500 convert w/ a 390 for a while...(got a '69 mach I and a '65 2+2 Mustang now )

edit: Got that #%*! error page again![:@]
thought we were done with that?[:'(]

w8ye

My Feedback: (16)

For the casual flyer, anything over 15% is not a cost effective expense.

Enjoy,

Jijm

William Robison

My Feedback: (3)

Hobbsy:

The best nitro percentage, in my opinion, is the lowest amount that gives you a good idle. If your HC FA-150 idles well on 5% then that's the fuel you should use in it.

Bill.

William Robison

My Feedback: (3)

Addendum to myu last.

Sure, you can get more power with higher nitro, but 99.999% of our planes are overpowered anyway, the higher nitro just increases the fuel consumption and cost without any better flying.

Again, my opinion.

Bill.

Hobbsy

My Feedback: (102)

Bill, I ran the 5% in the 1.50 and my Enya .53, on both the HS needle had to be leaned 1/4 turn, I don't think I want to run 20% castor though, I get some 5% WildCat with a blend.

Prop, that was my brothers XL, I had a 64 black Sprint.

Jack211

So, Jim and Bill, we ought not run high % nitromethane in our Saitos for the same reason we don't run nitromethane in our cars, as NASCAR does?

The high end nitro content fuels (over 15%) are just designed to get our money, not make our engines perform at their peak.

Jim, I guess I'd like you to define "casual" flyer. I fly a good deal, and I want my Saitos to give me dependable, unforgettable flight experience. Do "competition" fliers use higher nitro content just to spend their money, or is performance their goal?

I don't WANT to spend any more for the fuel than is REASONABLE--but I want great flying, great performance. If I can get all that with 5% nitro, cheaper, I will. I'm at only 1200 feet altitude, so I probably have the alternative. I just don't know. But if cost alone were my concern, I believe I'm in the wrong hobby. [I just paid $30 for a replacement cowl on my P-51D--the cowl I ruined when the Saito 1.0 died on the turn to my approach to landing, too low, too slow. Could I have saved that $259 bird with 30% nitro fuel? Don't answer that, too complicated: cowl exit size, tuning, fuel tank placement, heat, wind, pilot error, et al....]

J.

William Robison

My Feedback: (3)

Jack:

Run what you are happy with. Up in the land of idiots and other cold freaks (Haw!) you may well need the higher nitro to get decent engine runs.

But I'm dead serious about overpowering the planes. The one in this picture is my biggest twin, 84" wing span, with two high compression Saito FA-120 engines, and at 21 pounds don't try to hold it back.

Some background on this one. It was built by Carl "Flaps" Laffert, the building half of the Ed Moorman flying team. I got it from Ed. It's six years old, currently undergoing a refurbish.

Bill.

Jack211

Bill, those two 120s must sound great--and that bird's ugly enough to be absutively loveable.
j

William Robison

My Feedback: (3)

Jack:

What do you mean, ugly??? The deHavilland Dove had a lump on its head too, and Sky King liked the Cessna Bobcat so much he had one as the original Song Bird.

Bill.

w8ye

My Feedback: (16)

I think the casual flyer is a non 3D type that likes to have a little fun but his primary goal is not to crash the plane. I saw one crash today and almost another one. These guys were older guys that just like to fly. Wind was gusting in excess of 20 mph. I think the "almost" guy got his into a spin going into a turn and almost didn't recover?

The performance increase with increase in nitro content falls off in most engines as the % gets greater? With a Magnum four stroke, it just is a waste of money to run 30 heli.

The 3D guy with a 82 in a UCD 40 needs that 30% to effectively pull out of a vertical going bad.

I've been flying my Super Stick 60 with a Saito 91. It has plenty of power for my kind of flying. I'd get along fine in cooler weather with 5-10%. When it's nearly 100 out and the humidity is high, 15-20% would be better for me?

I was reading a competition control line four stroke epistle where the guy thought the the Saito hic-up went away when using Power Master 20-20. But on a real hot day, he would switch to 30 heli.

I was flying my Saito 91 today and there were no hic-ups. Temperature was in the mid 60's and I was running Omega 15%.

Everyone's opinion on stuff like this will most likely vary? Feel welcome to state your cause?

Enjoy,

Jim

Hobbsy

My Feedback: (102)

Jim and Bill, I ran my Saito .56 on the 5% Fox fuel today to do a little comparo to the Enya .53 for SkyPilot, I was impressed. It turned an APC 12x6 at 9,190 and idled a perfectly smooth idle at 2,160. The plug of course is a Fox Miracle Plug. Again I had to lean the HS needle about a quarter turn.

William Robison

My Feedback: (3)

Hobbsy:

Sounds like we should all switch to 5% fuel.

Bill.

w8ye

My Feedback: (16)

That appears to be good enough for some enjoyable flying.

Enjoy,

Jim

bldrums

New Saito 1.25 breaking in on my SpaceWalker. I'm now at the break in point of running the engine @ 8000 w/ 15 x 6 wood prop rather rich. Just for curiouas..courseosi...curosaty....because I was courious to see how much thrust it might be pulling , I tugged on the strap that was holding the plane by the tail. At first I looked to see where it was hung up because I wasn't pulling the airplane backwards. Yeah. Awsume. Its a wonder the 1.25 didn't pull the tail right off the plane!! Since my most powerful Saito so far is a .91 , the 1.25 , to me, is almost scary with power! ( but I will get over that for sure!)
Like all the Saitos so far, this thing is a piece of junk.


No I wont send it to you, you know Im kidding.

jlkonn

My Feedback: (1)

Bill,
Sky King...
Song Bird...
Man you are making me feel old 'cause I remember watching him!
I got one...
It didn't last long. Maybe one season if that.
It was back in the late '50s.
The show started with a Thunderchief, I think, flying directly overhead and the announcer saying:
Steeeeeeeeve Caaaaaaaaanyon!
To the Saito question.
I got my 1.00 back together.
Do I have the intake pushrod tube on wrong.
I know it can't fit like the exhaust since it's at more of an angle but I don't remember what it looked like before I took it apart.
JLK

William Robison

My Feedback: (3)

John:

Looks fine from here. If the tube wasn't seated properly in the tappet guide the little ridge nubbin near the top would be pushed up into the rocker box.

You got me on the Steve Canyon TV program. I remember Steve Canyon as a comic strip, and a black op we ran in Laos (Vang Pao, "Hard Rice," and the Good Guys), but not on TV. Maybe it was while Uncle was giving me my all-expenses paid vacation over there.

Bill.

coloradokurtis

Hey guys I have a quick question what is a safe max rpm for a .56
Thanks, Kurt

sl1200mk2

As stated a page or so back, I'm new to 4 strokes and still new to the hobby itself (a .91 being my 2nd engine).

I'm still trying to understand prop sizes and how to figure them out aside from huge trial and error. Going as per the Saito book and advise from the LHS (use the smaller prop), I'm breaking in my .91 with an 11x10. I also bought a 12x9 for post break-in. I plan on doing entry level 3d style flying - is this correct? I see postings of people using these huge props for 3d compared to what the book lists... what are the basics for selecting a proper prop size? My plane is a .46 sized U-can-do.

Also, I noticed the engine was very difficult starting on the first few breakin runs. I couldn't imagine starting this with a "stick". I had to use an electric starter by "bumping" the spinner - meaning running the starter up and then hitting the spinner. I didn't have to do this at all with my prior .46 2-stroke, so it concerns me a bit. I made sure the engine wasn't flooded even though it's an inverted mounting. I'm afraid I'm damaging something internal and not knowing it!

So far, with break-in, I've gotten 3 tanks through somewhere between 12-15 min each taking it easy and only really spooling the engine up to "full" RPM briefly on the last run. I'm taching full around 10.3k w/o touching the high end needle much (2.5 turns CCW as per the book).

I've copied a few posts about break-in proceedures, but I'm only about 26 pages through this thread so far! I'm sure my low end is very rich - it doesn't idle well at all. I'll work on this after the 4th or 5th tank tomorrow. I did notice a "burning" smell much more than my first 2 stroke - assuming this is just from such a rich setting?

Comments are always welcomed...

Regards,

Wayne

William Robison

My Feedback: (3)

Kurt:

According to "The Book" your FA-56is safe a little over 11K rpm, for maximum engine life try to keep it at 10,500 max.
------------------------------------------------
Wayne:

Prop selection is still partly a black art, but there are some ways to get close. You want to do 3D flying, so you want high thrust at a low air speed. A six inch pitch seems to be best with a 10K rpm engine such as your FA-91, and proper engine load should be with a 14' diameter. Therefore, for 3D strap on a 14x6 prop. This will also give you a top safe speed in the air of about 40 mph. And to keep from over speeding the engine you'll have to cut the throttle in a dive. If 40 mph is too slow, put the 12x9 on, it should get you up around 65 mph.

Bear in mind that the larger diameter, as a general rule, will make the engine run more smoothly.

Starting? Don't jam the starter against the spinner. Turn the prop backwards against compression, push the starter firmly against the spinner, then hit the starter switch. If it wont spin the engine this way you need a stronger starter. Jamming the starter wont hurt then engine, but it can cause premature failure of the starter, and it certainly makes the spinner ugly a lot faster.

Also, I've found the Saitos start best at about 1/4 throttle. they can be a bear trying to start cold with a closed carb. And a sloppy prime helps a lot.

Bill.

coloradokurtis

Thanks Bill.

Tom Jones

My Feedback: (4)

Mr. Robinson, How do you know if your engine has the quieting ramps on the cam gears. Is that an issue with the 100GK's, Thanks Tom