semi_conscious

blw -

Today I ran a few tanks through the .91... I'm using a 14x6 Dynathrust and leaned it to 9300 rpm for just a brief moment then a quarter turn took it back to 8800 or so.. I ran it for about 2 - 3 minutes at a time letting it cool before running again... each run I leaned it, then took it down richer and didn't run full throttle for all that long.. I got the low speed needle set and it idled at 2000 reliably.. with good transition to full throttle.

I need to order some different props.. and see what numbers I get as it gets more broken in ... any prop recomendations?

w8ye

My Feedback: (16)

The Dynathrust 14-6 should be good enough. I've used APC 13-8 and 14-6 as well as the MAS black 14-6.

The all did fine for general sport flying

ericrcpilot

My Feedback: (145)

I flew my X50 today with my 91 and 15X4W prop. I had a hard time not climbing while hovering as I was hovering at about 1/4 throttle. Any recomendations on a different prop where I could get the rpms up a little without pulling so much? I was wondering about a 16X4W? Do you think that would help?
Thanks, Eric

mikedsilva

only on 1/4 throttle?

some of my planes wont even taxi at 1/4 throttle!

JettPilot

My Feedback: (6)

You state that you want to get the RPM's up, but then asking about using a larger diameter prop, that will make the RPS LOWER. Try smaller diameter with higher pitch, like 14 X 6 if you want less thrust and more speed.

JettPilot

JPal101

My Feedback: (32)

What is the difference between thrust and speed? Is thrust momentary acceleration when you increase the throttle while speed is constant?

Hobbsy

My Feedback: (102)

Thrust is the pulling force generated by the prop, you could tie a scale to your fence and to the tail of plan and measure it, static thrust. This is with the prop in a stalled condition since it is not moving forward.

ericrcpilot

My Feedback: (145)

I think I will give a 14 X 6 a try and see what happens.

semi_conscious

w8ye-

is 9000 rpm with a 14x6 in the ballpark? with engine mounted on plane today.. 8800 - 9000 seemed to be the safe rpm for flight.. 9100 - 9200 when tweaked.

had a bit of a mishap that has me confused...

doing touch and go's today.. i throttled up to take off.. engine was running fairly rich.. it kicked back and got the prop loose.. then died... as i walked up to the plane i noticed something not right... the exhaust manifold had broken off right at the lock nut on the engine.. it had to have just happened when the engine quit.. because it was hanging there by the fuel tubing.. and i didnt notice any change in the sound of the motor before it kicked back..

the pipe seemed to have been bent a little. maybe crash damage from the previous owner.. only thing i can thiunk of..

w8ye

My Feedback: (16)

That's about what I get in the 3 that I have.

I bet the pipe broke on the roll and changed your fuel mixture and made the engine back fire and quit?

They don't make much more noise with the muffler off.

Do you have the straight all threaded pipe or the old style bent one

JettPilot

My Feedback: (6)

Where is William Robinson ????

I am considering switching to Magnum or some other engine if William is not here to support our Saitos [X(] If Saito were smart, they would just put William on the payroll

JettPilot

William Robison

My Feedback: (3)

JP:

Relax please, Sir. I have really been busy, and haven’t had as much time for RCU as I usually have. Looks like it’s going to stay this way for about another two weeks and everything will be back to normal.

Besides, you can’t scare me talking about Magnum engines, I like them too.

Haw.

Bill.

PS: Just don’t ask me about Oriental Scrap brand engines. Haw again. wr.

William Robison

My Feedback: (3)

More catch up, I’ll try to make it to the end this time.

crtmmac:

As I said in another thread, the tappets get a fine ridge hammered into the rubbing end, and they wont come out. You have to pull the cam shaft out and the tappets then will go out of the guides toward the cam. After they are out you can clean the ridge off, then they can be put back in from the outside. You said you didn’t find any thrust washers on the cam when you pulled the axle, better look again.

RVM:

Almost without question when the RPM surges with nothing being changed it’s a fuel problem. Sure you haven’t missed something?

There is another possibility I’ve been seeing lately, and that’s sticking tappets. Go [link=http://www.rcuniverse.com/forum/m_4567779/mpage_2/tm.htm]here[/link] starting in post 41 for a discussion and pictures. I’ll condense these posta and add them to Saito Notes in the future.

Your question about ARO – any “Dexron” type ATF is good for use as ARO.

PLAM:

The gasket on the cam box can be selected to get the correct gear mesh, sounds like you did it the hard way. What gasket did you use? The standard replacement gasket is 0.007” uncompressed, when doing a “Max Accuracy” fitting I’ve gone as thin as 0.001” and that sounds like what you could have used, saved all the hard work of lapping.

Scratch:

The Saito two needle carb has to keep the throttle barrel pulled out, if your linkage is pushing it in you can definitely have mixture problems.

All:

The black painted cylinder looks good, but it’s more than that. A dark color radiated heat much better than the lighter colors. Helps to keep from overheating. You do have to be careful not to get the coating, whether paint, powder coat, or what, too thick.

And I think Saito has seen the light on the case vent – all the newer designs have it mounted up near the cam shaft area. The FA-180 that Jim mentioned wasn’t really a new design, it was just a punched out 150. And the FA-125 Barry mentioned is, again, an FA-100 rework.

Bill #108:

I don’t know what to say about your loss of rpm with the stacks mounted, that has certainly not been my experience. I’ve seen some postings saying they have a loss of 100 rpm or so with the Bru-Line air filter, but nothing about a power loss with the stack only. Can you do some more experimentation and see if there’s a combination that works for you? It would be appreciated.

Also, as I have said before, I’ve been really busy. I charge $1200 for an eight hour day, when people start waving bundles of cash at me I sometimes find it hard to say no. Besides, I don’t have my post count up to 20,000 yet. Haw.

Jug Al:

As Jim said, you wont get a good idle on your FA-180 until the engine has at least an hour on it, more likely two or three hours before it really settles down.

Getting long again, better post this one and start over.

Bill.

William Robison

My Feedback: (3)

Hobbsy:

If that intake seal on your FA-40a is similar to the upper seals for the push rod tubes, it could have been a trial of a smaller diameter intake pipe, the sleeve was to keep it from vibrating. Why a smaller pipe? Keeps the mixture velocity up at low throttle settings, prevents fuel condensation, and gives a better idle.

I think a good part of the FA-72 back plate problem was a smaller pipe there too. What Saito did was to use the FA-80 cylinder, just redid it to be AAC instead of ABC. Then with the smaller diameter intake pipe it wasn’t held firmly, allowed to vibrate, and eat the o-ring. Had the pipe been a snug fit the problem may never have appeared.

Motorman:

I’m running three Pitts mufflers, and I’ve never had a problem either. My advice in case of a problem with one is based on other people’s comments. I do have to say that none of mine are from Performance Specialties, and my Magnehelic gauge says I’m getting 6-7 inches water pressure at full throttle. The people who get zilch pressure are the ones with problems.

At the same time, I don’t run either Cline or Iron Bay systems, I just don’t like the thought of the fuel system running 10-12 psi inside the plane – I worry about leaks. At the same time I have a dozen or so Perry pump systems working with no problem.

Kim:

If your FA-80 is the ABC version it’s high compression. The AAC engines are the low compression ones.

Jim:

I have to call you on the lug code. My FA-80 is the high compression version, and it’s stamped “K.” I got it used, so I have to allow the possibility someone has mixed parts up and it originally had the “A” stamp.

Whew! Think I’m caught up!

Bill.

William Robison

My Feedback: (3)

Latest additions to Club Saito membership:

351 p-80
352 airboss82
353 RGN01
354 rustypep
355 crtmmac
356 davidjguerra
357 semi_conscious
358 hrrcflyer
359 P47 Jug - Al
360 huck328

Welcome to you all.

If I've missed anybody please yell, I'll add you.

Bill.

IronCross

I see Club Saito is comeing up on it's first aniversary (8/30)... Would think a celibration would be in order .. Lets see, party at .......... house ?..

Iflyglow

My Feedback: (79)

Bill,
You will never have 10+ lbs from muffler pressure, it is more like about 2-3 lb's. I have never had a leak with any pressure equiped fuel systems, and I also fly YS's. I allways check the tank under water first with air pressure far higher than what the airplane will ever see.
You should not knock it if you have never tried it. The Cline will make the Saito run really consistant, far better than just muffler pressure. My engines run identical from full tank to empty tank, they never go lean nomatter what the attitude of the plane.

upssteve

My Feedback: (11)

i would like to join and have questions

upssteve

My Feedback: (11)

bill what steps do i take to stop fuel from filling up model with saito 125 on x100 funtana. fuel sputters badly from carb. havent touched low speed needle and dont know much about 4 strokes

Kimhoff

My Feedback: (22)

Quote

Kim:

If your FA-80 is the ABC version it’s high compression. The AAC engines are the low compression ones.

Jim:

Now for the dumb question. Waht does ABC and AAC stand for and how do I tell the difference?


Thanks

blw

My Feedback: (3)

Kim- The first letter is the material of the piston. A=aluminum. The next two letters are the material of the liner, or cylinder head for Saitos, and then the material used to plate it. So, ABC is an aluminum piston with a brass liner that is chromed. AAC is the one piece aluminum cylinder head that is chromed in most Saitos. If you see ABN, that would be the OS method of using aluminum pistons and plating the brass liners with nickel. OS has had problems with the nickel peeling off but some of this seems to have been cured. There is a recent thread of an OS .35 heli engine that peeled the liner with photos showing the damage.

William Robison

My Feedback: (3)

IC:

Going back, I see Sigman’s first post was 8/28 rather than 8/30, but who’s counting? How would you suggest we celebrate the birthday? My suggestion is for everyone to send $100 to my PayPal account. What do you think?

Haw.

Motorman:

As I said, I’m a Perry pump fan, Cline information is just passed on.

UpsSteve:

You are in, your member number is 361, and welcome.

Spitting fuel out of the intake is something we will always have on a piston engine, except the most mildly tuned ones. It’s caused by the intake valve staying open past the point where the piston starts back up in the cylinder, it blows some of the intake mixture back out. You may have noticed the black stain on the air cleaner cover of your car – same thing – and the “Hotter” the engine the more it will do it.

Seems like the designers would avoid such things, but at higher rpm the intake mixture doesn’t have enough time to reverse, and the engine gets more fuel and air. So, to get the higher power at elevated rpm we have to put up with the engine being a little slobbery at lower speed.

But there is a cure. An intake stack fitted with a Bru-Line fine mesh air filter. These two in combination will trap the fuel spray, holding it for the next intake cycle. Not only does this keep your plane a lot cleaner, it makes the engine a lot more economical. Some have said as much as 30% longer flights on the same amount of fuel.

Your FA-125 will use the SAI50GK93 stack and the BRU202 filter. These are the part numbers that Horizon uses, you can order both parts from them.

Even without the stack and filter as you get the engine run in and the mixture leaned out this spray will decrease greatly, but the stack and filter are strongly recommended.

Kim:

Barry has told you what, but not how to tell them apart. The weight is an easy one, but unless you have both at hand it wont work. First two attached pictures show the base flange, you can see the brass color on the ABC version. Easier yet is just to pop the rocker cover and look at the valve guide. On the ABC cylinder the guide, inner part of the intake port, and the valve seat are one piece inserted from the inside. The only bronze you see inside the rocker box is directly against the valve stem, you have to look inside the valve spring to see it. The AAC cylinder has the inlet port and the valve seat integral to the cylinder, the bronze guide is inserted from the top, and the metal of the guide extends outside the spring. See the 3rd picture.

Bill.

William Robison

My Feedback: (3)

Kim:

One further note on the mid-block engine with ABC cylinders. They came with smaller valve springs than the AAC cylinders. OEM on the ABC had a 6.95 mm coil diameter, these are no longer supplied. The later springs are 7.15 mm coil diameter, they will not fit into the original spring recesses of the earlier cylinder. If yours is ABC you’ll have to do a bit of machine work to get the newer springs in, but they can be made to work. Should you, or anyone else need/want the work done I have the tooling, I’ve already modified quite a few. Send me the cylinder only or the complete engine, I can do it without taking the engine apart. If you include the new valve springs the only charge is postage both ways.

Bill.

>>EDIT to add picture comparing springs. wr.

RVM

What would the benefit to this be? Less valve flutter?

William Robison

My Feedback: (3)

RVM (and others):

The spring with the larger coil diameter has a longer fatigue life, all other things being equal. I have seen some of the smaller springs break, but haven’t seen any of the later ones fail.

So the advantage is longer life.

Bill.