rlmcnii

My Feedback: (3)

RVM,

I have never used the pinch-test in any of its forms. I can not make any comment about it. Many people seem to use it with great success.

Adjust the HS ONLY at wide-open-throttle. Most of the experienced Saito-operators advise about 300 rpm rich of peak.

The LS in these engines controls them through more than 50% of the rev-range. The tuning of the LS will control how well you like your Saito. When properly tuned they are pretty efficient. Here again, the old hands say to figure 1 ounce of fuel per minute per cubic inch at wide-open-throttle. The fuel consumption drops radically when operated at less than wide-open.

The .91s are nice engines.

P.S. WR's advice concerning the stack and filter is, as usual, correct. Very worthwhile.

Hobbsy

My Feedback: (102)

(Quote), Saitos run very well with the LS set way too rich...they just make a lot of smoke and burn a lot of fuel doing so.







A rich midrange is also the cause of 95% of the shaking Saitos get accused of.

loughbd

RVM.

Castor oil is not red. It is a light tan color. If yours is red it's because it had dye added to it.

How come I don't use an air filter or velocity stack in any of my Saito engines ( or any engine) and mine don't make a "big mess"? The only mess from mine is from the exhaust and it's no more than anyother and not all that big a problem anyway. As for endurance?? 32 minutes on six ounces from a Saito FA45 seems more than reasonable.

Hobbsy

My Feedback: (102)

I just made this velocity stack for my Saito 1.25. I used a piece of 3/8 ID KS tubing. I slit a piece length wise and kept pushing it together with my miniature vise and re-slitting it with my band saw until it would tightly slip into a choke bracket left over from a choke removal. I had drilled the choke bracket out slightly so the final ID of the stack would be .5mm larger than the carb venturi. I closed the seam and soldered the stack to the bracket using Silver Solder, the stack extends 1/16th inch inside the choke bracket and rests up against one of the white rings from a previous choke removal. My neighbors and a couple of friends are out enjoying their pool so I'll run the engine tomorrow. The length is 1.125 inches at the halfway point of the baloney cut.

XJet

Your stack will provide *much* less restriction to the incoming air if you flare the open end into a bell-mouth.

I've done extensive work with intake systems on pulsejets -- which are surprisingly similar because they (like the intake system of a single-cylinder 4-stroke) are not constant flow.

If you don't have the bellmouth, a vortex ring forms at the inside edge of the open end and this ring can significantly reduce the effective cross-sectional area of the tube at this point -- in other words it will choke your engine.

Flaring the end means that the vortex is not only smaller (because the air isn't crossing the edge at 90 degrees) but is also formed outside the diameter of the actual tube itself.

You'd be absolutely astonished at just how restrictive that vortex is when sucking air through an unflared pipe -- it can reduce the effective cross-sectional area by over 25% in some cases.

Hobbsy

My Feedback: (102)

Thanks X, I will try to get a piece of tubing close the size I cut mine down to and flair it with a ball bearing or a flairing tool if it will fit. I gather that the baloney cut won't get it.

RWeber

I have my very first glow motor a Saito 180 Golden Knight and it is on my 60-120 size Stearman and I seem to be having problems with the Pro Zinger wood props coming loose and tearing up the cone and at the same time causing a backlash that has stopped the motor twice. anyone have any advice that came help me out or know where to send me. I don't wanna tear up my favorite motor.

w8ye

My Feedback: (16)

Welcome to RCU.

You are trying to run your 180 too lean and it is backfiring and throwing the prop

Uncle Ted

I am having trouble getting an idle on a new Saito 80 set below 4000 rpm. I have run more than a gallon of Wildcat 15% Premium Extra through the engine. Engine peaks w/ a 12.5x6 APC prop at 9800 and I set high speed needle at 9200. But idling at less than 4000, it stops abruptly. Carburetor was rotated. Does fuel intake pipe into engine have a tendency to leak air? Does the carb spew fuel as the engine compartment seem loaded with fuel after running. My fuel tank has been tested for air leaks and is sound .HELP as I am not happy with this engine , my first Saito.

blw

My Feedback: (3)

We have a new hobby shop in town and I ordered 2 new backplates for my .72 and .82. Dunno when they will get here.

I don't know about the vortex ring around TorqueWrench's stack, but I think it will not have a Bournoulli effect like the Saito one. I always thought they would squeeze the air just a little going into the carb. Would his angle of cut change the air flow?

Bill, my mess inside of the cowl did get fixed with the stack. I'm not sure about fuel consumption and this is the wrong time of year to check on that. I have a weather station that was a gift and I'm noticing humidity jump from 50% down to 35, then back up to 65, then all over. It goes high around sundown. It was 90% around lunchtime this afternoon. How can anyone really set a good tuning with these conditions? With all these conditions for fuel mixture variations, I would say that I'm doing pretty good with the stack. I know that max RPMs jump up and down when I'm flying and I'm still guessing that I average 20+ minutes on an 8 oz tank with lots of stall turns, vertical things, etc at full throttle.

rimcnii- the LS will affect all the way up to wide open throttle if it is set too lean. You can't peak my .72 if the LS is lean.

William Robison

My Feedback: (3)

All:

As TW said, the Saitos run quite happily with an excessively rich mid range, and when it’s leaned to a proper running mixture the majority of the vibration goes away.

TW:

Xjet is correct about the nasty vortices generated at the open end of your stack. A trick learned many years ago to compensate without having to bell the end is really simple – cut it at a 45 degree angle. Simple, quick, easy, and inexpensive. What I can see of yours looks like you’ve already done it.

Rweber:

Agreement with W8YE Jim – you’re running your LS �way lean.

And I’ve enrolled you as member number 343 in Club Saito. Welcome.

Uncle Ted:

And you are on the books now as member number 344. A welcome to you as well.

You have picked the “Black Sheep” of the Saito line for your first. The FA-80 is without question the hardest of all Saitos to get right.

First suggestion is to get the SAI80144 carb upgrade kit and install it, then open the LS at least one full turn. Make sure you can go blubbery rich at full throttle, then peak the HS needle AT FULL THROTTLE ONLY, then close the throttle and drop the rpm, you should be able to get 2500 rpm or so, after leaning the LS it should come down around 2000 rpm and still transition well.

Bill.

Kmot

My Feedback: (24)

Torque Wrench: Nice work on the "stack"! I plan on making my own version of the "Saito Stack" and although it won't have a parabolic curve, it will be wider at the mouth than the base. Like a cone. Because all I can do on my small lathe is a straight cut, not a curved cut.

XJet

Another advantage of the angled cut is that effectively "detunes" the intake system so as to avoid a standing wave being set up at certain RPMs (albeit much higher than you're going to see on that Saito :-). Of course in the pulsejet world we want standing waves so we try to make the intake and exhaust tubes resonant.

If you set up the stack so the angled cut faces the propwash you might even get a *tiny* amount of ram-effect :-)

William Robison

My Feedback: (3)

XJ:

My very first experimental stack, maybe 15 years in service, still works fine. Clean airplane and low fuel rate.

Bill.

PS: A Magnum 25 GP engine. wr.

loughbd

I have a 8aito 80GK that is exactly ten years old as I bought it for my Dad's 50th anniversary in 1996. He didn't need it and gave it to me. It was no harder than any onther Saito to set and runs just fine. It has been in a Sig Hog Bipe since it was new that was given to me by Harold Hester. The only thing "black" about it is the color.

Hobbsy

My Feedback: (102)

I ran the 1.25 with the stack, yesterdays numbers without the stack with the 15x8 and 15% nitro were 8,561 and todays using the stack are 8,665, so I dunno. I held the back of my index finger in different positions around the stack at different throttle settings, the only time could feel fuel was at full throttle and that was barely discernable. It is 104 degrees where I ran the engine.

loughbd

here's some pictures of that 10 year old "black sheep" Saito 80. Top Flite 14x6, OS type "f" plug, 12 1/2 %nitro, 19% 60/40 castor/synthetic oil. 9200 RPM. 6 minutes on 6 ounces and no fuel coming out the intake. Standard old non "stack" carb. This engine was a joy to set up. One flip start, set needle and go play. No more difficult than any of the other saitos I own and easier than a couple.

Oh by the way. Thr shiney silver muffler was completey black with burnt on oil. 10 minutes in hot Cheveron perfect engine cleaner made it look like this. Beats all night in a 20 dollar crock pot that you can never use again.

JPal101

My Feedback: (32)

The owner of my local HS is a machinist by trade. I am going to ask him if he could make a velocity stack for my 125, can anyone recommend the proper length and diameter of the stack to achieve the maximum performance

Hobbsy

My Feedback: (102)

I was talking to WR on the phone a while ago and I believe he said approx one inch from the spray bar to the end of the stack, mine is probably 1.25 from the spraybar but works well I'm not changing it.

Bruce, is that one the early high compression .80s, I have one from about 1992, it has some serious compression pressure. It is my most run and most flown Saito having spent most of its life on a Kombat 60 from the Airplane Factory.

mprediger

My Feedback: (11)

William Robison kindly sent me all the Saito manuals he had on line (as .pdf's) as well as the latest "Notes" document. I have posted them on my site - www.musictechconsulting.com - after the opening screen the main page has menus on the left "Radio Control" is the one you want. Will be adding more categories in the future. Please feel free to submit documents, info, photos. Just PM me with questions or comments. Bill already has enough to do and this stuff is on my own server. BTW server is fast but my upstream bandwith is not the best - patience.

Best regards and good flying,
mike

loughbd

It has the same compression as ALL the saito 80's except the FA80T Twin which is basically 2 old FA40's

Hobbsy

My Feedback: (102)

The early 1.50s and .80s had very high compression that was lowered somewhere along the line. I have one of each.

w8ye

My Feedback: (16)

It is a well known and long established fact that the very first 150's and 80's had very high compression.

loughbd

Funny, I have one of the very first I got when working for Hobby Shack and I also have one that is less that 5 years ago and they have the same compression ratio, I read this urban legend on RCU and checked both engines buy using water. Fill the cylinder at BDC and measure the amount then fill the cylinder at TDC and measure the amount. Take the ratio of one to the other and get the compression ration. They are the same on both of my engines.

William Robison

My Feedback: (3)

Jpal:

The length of the stack from the spray bar to the open end should be roughly four times the inside diameter of he carb, or a little more. The one I was talking to TW about is an FA-82a, it’s roughly an inch from the spray bar to the end of the stack. And, since Saito only supplies the SAI50GK93 for all the mid block engines, the total length will be the same for all, but the length to carb bore ratio will be different for different engines – smaller carb on one, larger on another. If you are making your own stack the four to one ratio is about minimum, longer wont hurt, shorter wont trap all the fuel.

Quote:

ORIGINAL: Loughbd
It has the same compression as ALL the saito 80's except the FA80T

Sorry, Bruce. Wrong again.

Regarding the “High” compression FA-80 engines, let’s get it right. There were indeed two different versions of the FA-80. The early engines were ABC construction, and the compression was such that 15% nitro was the maximum for good running. Then when the FA-72 was introduced the construction was changed to AAC and the compression lowered. Why did the FA-72 affect the FA-80? The FA-72 has the same bore as the FA-80, it is, in effect, a destroked FA-80. The cylinder, piston, ring, valves, rockers, everything above the cylinder joint has the same part number for the two engines.

One minor point on the ABC version FA-80. The currently supplied valve springs will not fit without a minor bit of machine work, the later springs have a larger coil diameter. I have made a cutter to open the spring pockets if anyone needs to change the springs in an older engine.

Bill.