7capCub

Looking for advice on a Saito FA-50.

I have two older Saito FA-50s. I've owned them only for a few weeks. The first engine runs strong and doesn't have alot of hours on it. Compression is very good.

The second engine is also an FA-50 and has a lot more hours on it. I removed the exhaust and looking at the stem of the exhaust valve there is a lot of carbon build up. Not just a thin coating but thicker crystaline structures formed.

When I turn both engines over by hand you can feel a difference in compression between the two engines. Even though the engine with lower compression still "pops" when you flip it over and it does run.

The next experiment I performed was to rotate the crank until the piston is mid stroke (not at the top or bottom) and then stop. Now gently wiggle (rotate back and forth) the crank to gauge the amount of slop. The higher milage engine has about twice the rotational slop as the first engine. I'm using the first engine as a reference becuase I would expect some amount of slop or "play".

I have priced most of the components from Horizon Hobby and the repair costs go up fast. Piston, connecting rod and crankshaft. Probably both bearings as well.

My intention is to use these on a Top Flight DC-3.

I need to do one more experiment. Set up the first engine with a standard prop and record the peaked RPM. And then setup the other engine with the same prop to see if they spin close to the same speed. I don't know if the difference in hand-measured compression will mean anything.

I guess my question is.... does it make sense to spend and time and money on this engine to try to get it to match the first one? Does anyone feel this engine has ANY life in it?
If I do nothing, and just run it, is the common failure mode a total meltdown (like throw a rod)?

Thanks, Erik

William Robison

My Feedback: (3)

Corwin38:

The later FA-120 has a fairly hot cam, with the valve lash set to minimum for maximum power the idle can be lumpy. You can keep the rpm around 2200 and have a nice idle, or you can (NOT RECOMMENDED) st the valves looser, up to 0.1 mm, for a smooth idle.
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Jack211:

After run oil put in the intake does no good. It has to go in the bottom end of the engine. Use a syringe and out an ounce or two in the crankcase vent, then tip the engine nose down to let it run through the rear bearing into the front bearing. After this, bring the engine back level and flip it three or four times by hand - this will blow the excess oil out the vent - then spin the engine with the starter for 15 seconds or so. Then you have good protection.
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7capCub:

Sounds like your older engine might be due for a con rod replacement, possibly a piston ring. These engines seldom need a new piston. Get your bearings from Paul at RC-Bearings.com , the ceramic set is preferred, about $30 for the two.

When you pull the engine down you can scrape the deposits from the valve stems, be careful not to touch the seating face. DO NOT lap the valves, just be sure you put them back in their original position, that is the exhaust in the exhaust and the intake back on its side. If needed you can use a pencil eraser to clean the valve face and seat, don't use any compound.

And do replace the valve springs, the get weak with age.

As a final note, your weaker engine could easily have an older grind cam shaft. If so it will never match the later engine. I'd suggest replacing the bearings and valve springs in both, while they are apart you can compare the cams.
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Hope this helps all of you in one way or another.

Bill.

7capCub

Thank you Bill! I will take a look inside! Erik

7capCub

I see talk about after run oils.. I've been using regular Marval Mystery Oil for a few months and haven't seen any problems. Many people talk about the Air Tool version is there a difference?

Thanks, Erik

w8ye

My Feedback: (16)

either will be fine.

Jack211

Bill, aro in the crank breather by syringe. Turn over up and down, then rev prop to circulate. Got it. Thanks.

Glad to be aboard,

Jack

Kmot

My Feedback: (24)

My latest Extreme Makeover. A Saito 120, early version. Just mocked up so far now that the paint is cured.

pedro_guim

Hi!
Please Help me...
I don't know where to buy a Saito 72 at the better price in Europe... I live in Portugal!
Can someone help me?
Thanks

Corwin38

My Feedback: (2)

Thanks for the info Bill. I forgot to mention that the first day I was having problems I went through a tank of fuel (17 oz.) in about 10 minutes, which seemed really fast to me. I haven't had a chance to check this again because of bad weather. Does this give you any more ideas?

Thanks,
Dale

William Robison

My Feedback: (3)

Dale:

Check the cam timing. You might be one tooth fast.
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Tom:

That's an old one. ABC cylinder and air bleed carb. I like it.

Bill.

Larry Benson

A question for the Saito crowd, I'm new to the 4 stroke realm and I have a little used Saito FA-65 my question is will it have enough power to fly a 83" wing span J3 Cub ? I have one coming and this is the largest engine I have. Airplane box says 60-90 2 stroke, I don't know the weight of the plane yet. not looking for acrobatic performance only realistic flying. what prop would you suggest also? .......... thanks for any help or comment.......... Larry

w8ye

My Feedback: (16)

The engine will be fine. A cub doesn't need much power.

Enjoy,

Jim

Kmot

My Feedback: (24)

Larry, I flew a Goldberg Anniversary Cub (71") on a Saito 45. It wasn't overpowered by any means, but it was powerful enough. So your 65 should be pretty decent in your 83" Cub.

Hobbsy

My Feedback: (102)

Low Speed needle still too rich, peak the HS needle and then turn the LS needle CW 1/8th turn at a time checking the transition and HS performance after every other change. When you get the best idle you'll be a little too lean for a good transition, richen it CCW 1/8 turn and re-check the transition, now richen the HS needle for safe running, I use 200 rpm for engine health.

Kmot

My Feedback: (24)

Dec 3, 2005 ^^^^^

Bill, have you had a chance to tackle this?

Quick question: I am putting my carb together now. In my gasket kit for the engine, there came a tiny o-ring. It looks like it might go under the tee for the needle valve where the tee screws into the mixture disc. But I do not recall removing an o-ring when I disassembled the carb a couple months ago and I cannot find one in my parts pile from the carb.

Is this suppsed to gu under the tee? If not, any idea where this o-ring is supposed to go? It is about 2mm in diameter.

-Tom

William Robison

My Feedback: (3)

Tom:

The AB carb tutorial is not finished. And yes, laziness and procrastination have had their effect on its completion. The notes on fabrication of the intake stacks is in the same queue.

Your speculation about the installed position of that small o-ring is correct, but it's only used on the later TN carbs.

The earlier carbs, both AB and TN can be modified to use it. See picture. Use a drill bit, BY HAND, and cut a slight chamfer in the mixture disc. Then with the jam nut on the tee slide the o-ring on the tee, and assemble.

Bill.

>>EDIT: Forgot to say - both jam nut AND clicker spring on the tee before the o-ring. wr.

Kmot

My Feedback: (24)

Thanks Bill.

Look what I found by checking parts. It appears there is an updated cam gear shaft that has an o-ring as well.

http://www.horizonhobby.com/Shop/ByC...rodID=SAI5036A

William Robison

My Feedback: (3)

Tom:

Forgot about that one, but it only has the ring on the front end. Guess they want the other end to leak normally. Haw. I've seen the shafts with the o-ring, but I've never needed to replace one.

Bill.

w8ye

My Feedback: (16)

When you buy a gasket set, they include one of those tiny Orings.

It is difficult to get one of the new shafts in place when it has a new O-ring.

My older Saito's seem to leak oil out the end of the cam pivot shaft before any other place other than the vent.

Enjoy,

Jim

Kmot

My Feedback: (24)

Well, I placed the o-ring in the mixture disc and didn't need to do any modifying. Anyway, here it is all all rarin' to go but I am waiting on a new drive washer as the original had plier scars all over it (I hate guys that do that, ugh!)

William Robison

My Feedback: (3)

Tom:

I like it. But the green case? re you trying to make us think it's a Perkins diesel?

Haw.

Bill.

rexracer

First off, I have to say this is a great thread... very informative. I'm fairly new to RC airplanes (2 yrs.) but I bought my first (and so far only) Saito more than a year ago. It's a 1.80. I've been waiting to put it in something, and this years christmas present from the wife is a GP Super Stearman. I do have a question on puting my 1.80 in this plane, though. If I leave the tank in the stock position, it's centered on the engines crank, or about 1 1/2" above the spray bar. It looks like moving the tank down will be a major PIA so I would rather not if I can help it. Thoughts? Oh, and Bill (I feel like I know you!) you can put me down for your book (manual?) when you finish it.
I've wanted to post here for 2 days, but I just finished reading all the previous post (yeah, 54 pages... a personal record for a forum)Oh, BTW. I couldn't leave that beautiful engine alone, so I built a test stand, and ran about half a gallon through it this past summer...what a sound. I started leaning it out a little towards the end, and even though I have alot of tuning to go, she's turning an APC 16-8 at 9300 rpm and idling at 2400. I didn't touch the low end yet. I plan on running a 17-8 on the stearman. Thanks for all the help from the previous posts.
Randy.

William Robison

My Feedback: (3)

Randy:

Quote:

...centered on the engines crank, or about 1 1/2" above the spray bar...

The cure is simple - mount the engine sideways. You can still stick the exhaust out the bottom of the cowling.

Not only will this put the tank at the right height, the engine is less critical on tuning than when it's inverted.

Hope you enjoy the plane.

Bill.

Kmot

My Feedback: (24)

Thanks Bill!

Well, I was not familiar with a Perkins diesel so I did a google image search and finally found a green one on the 8th page! Most are not green!

Dauntae

Holy buggers, I just spent about an hour reading and I skipped A LOT of pages, Lost count of Bills numbering... My poor wittle eyes hurt BUT I WANT IN CLUB SAITO..... Have a 150 in a CG extra and a 100 waiting to go in a almost finished Hog bipe, After I got my 150 purring like a kitten I was sold on saito.... my poor 2 strokes are getting dusty.

Dauntae