Hobbsy

My Feedback: (102)

Also Bill. here are two tests of .65's by Clarence Lee and Peter Chinn. I didn't read them thoroughly to find the difference if any.

http://sceptreflight.net/Model%20Engine%20Tests/Saito%20FA-65%20%282%29.html

This one by Peter Chinn

http://sceptreflight.net/Model%20Eng...o%20FA-65.html

Bill Lowen

Thank you.. I had found the parts list for Macgregor which was very helpful in obtaining the part numbers I needed for my engine. I had an older version of the other document you provided and it is kind of confirming to me that all of the small to medium single cylinder 4 strokes are basically built the same way. meaning the official manual covers just more than my 65? The engine breakdown is pretty good but what I really need is an exploded view of the carb. The view on the manual does not show all the little o ring placements and that kit I ordered has a lot more o rings than I removed from the carb. Does anybody have any detail pictures or PDF files of the carb..

The other thing is if I decide to order a new carb for this engine, I have noticed that all of the part numbers start with SAI65... which identifies my engine, however the number for the carb, as well as many other parts, show SAI50.... So I am assuming a lot of these engine parts are interchangeable.

Thanks for the help and sorry if this is common knowledge among the Saito vets.. I am just coming up to speed with 4 strokes but the quality of this Saito engine is top notch.. Even though this one is not running at the moment you can always tell when something is well built when you handle it. This will not be the last Saito I own.

Hobbsy

My Feedback: (102)

Bill, I did an autopsy on my .80 carb, there is a tiny O-ring that goes in the end of the spray bar, I'll picture the 2.20 one since its easy to see. The very thin one, not pictured goes on the spray bar before the tension clip and disappears. You can see the thin one buried in the carb body around the spray bar.
If you have other questions, just holler.

PS, the package pictured is for a 1.00, I rebuilt a 1.00 a few months ago and ordered two of the packages.

Bill Lowen

Hobbsy-- great reads on your first post.. Thank you.. Thanks for the pics too.. That carb looks just like mine so I assumed correctly that the carbs all interchange from the 50 all the way to the 100 (at least) so there are only the two o rings that I pulled out..which makes me feel a bit better..



edited for a duh moment...

Hobbsy

My Feedback: (102)

Actually the screw you refer to is the idle stop/speed screw, the midrange is the taper on the LS screw, I'll see if I can a picture of that.

Bill Lowen

another duh moment.. see below..

Bill Lowen

ok.. a light bulb just went on after some more reading.. that is the throttle adjustment screw.. which allows you too knock down the idle much the way you would with the sub trim setting on the transmitter.. very nice feature!! so I just adjust that after I do the High speed needle and low end mixture?

Cougar429

My Feedback: (3)

Bill, welcome to the Saito club. You'll be hooked for life now.

That screw can be set to allow the throttle barrel to JUST close even before mounting. It should not be used to set the idle speed since it would then prevent stopping the engine with the radio. I normally set mine so the throttle trim on the Tx controls the idle speed and the spring loaded "Trainer" switch is programmed to close the throttle completely when I want it to stop.

When you first stated it would not run, wanted to ask if you confirmed good compression. Asking as there are a few things that can stump getting one of these firing off that can be exacerbated from long storage:

First is a stuck or leaking valve. If it sat with one or both of the valves open for a long time then carbon on the exhaust, gummed up lube or simply a bit of carbon stuck between the valve and seat can cause a compression robbing leak. You can tell where this is coming from by simply listening at the intake or exhaust ports while winding the motor around to compression stroke. A hissing or whistling will tell you that compression is forcing air out somewhere.

NOTE: You will near that whistling anyway from the case vent as a normal process from the piston moving up and down, so will have to try and focus on the ports instead.

Second and more insidious would be a result of a hard stoppage and I have ONLY seen this on a 65. A friend had me tear his down since after a boink he could not get it started. I found it had torn some cam teeth loose so the crank was turning, but the cam was not. Does rotating the crank have the rockers activate?

A final cause of low compression would be a stuck ring. I once added a metal conditioner to my standard After Run Oil mix as it had a pretty tenacious "Stickiness" I thought would make it bond to surfaces better for storage and protection. Worked that way quite well, unfortunately it also seemed to harden pretty good after a while. With engines stored successfully for 20 years or more with my stock 50/50 mix of ARO and Air Tool Oil, to see this occur with the second 125 in approx a year was disappointing and required a teardown to free the ring.

Last and most simple is a failed glow plug. Have you tried the plug out of the head to see if it works?

Also the final question, how do you have it mounted? Orientation and tank height can perhaps be the problem and simple changes all that are required to solve it.

Only warning I give to new 4-stroke owners is to NEVER have yourself or others in front of the engine or to the sides, especially when first setting them up. Saitos do not like to run lean and can stop on a dime once you wind them up to work on the HS needle. This frequently ejects the prop at high speed and energies.

Cougar429

My Feedback: (3)

Did not want to hijack Bill's topic with this since it relates to the 65.

As I posted earlier I grabbed another for $40 recently and got into it this week. Some of the stuff was expected, but to see a bolt as a crank spacer caught me off guard a bit.Was able to measure and fab one up to set the crank gear to front bearing load correctly.

I'm hoping someone has what's left of a 65 sitting in storage or spares to be able to grab what I need to put this one back together. The rear cover is missing a corner outboard of a mounting screw, but I am more in need of an intake valve and keeper, rocker pivot and those pesky top seals for the pushrod tubes. The little, rarely needed or stocked bits.

Oh yes, this one was also missing the odd 7mm prop safety nut. I can fab up a washer, but no general supplier for the nut(s).

WHY don't suppliers separate spares by engine size? My eyes hurt.........

Hobbsy

My Feedback: (102)

Here is a picture of the LS screw, not a very good one though, I took 7 pictures and only got one that is nearly acceptable.

Bill Lowen

Bill, welcome to the Saito club. You'll be hooked for life now.

Thank you for the warm welcome! and you are right.. I am hooked.. I also enjoy the OS engines,, I have a couple of 46AX 2S and a 52FS.. I am going to answer your questions below..

That screw can be set to allow the throttle barrel to JUST close even before mounting. It should not be used to set the idle speed since it would then prevent stopping the engine with the radio. I normally set mine so the throttle trim on the Tx controls the idle speed and the spring loaded "Trainer" switch is programmed to close the throttle completely when I want it to stop.



When you first stated it would not run, wanted to ask if you confirmed good compression. Asking as there are a few things that can stump getting one of these firing off that can be exacerbated from long storage:

First is a stuck or leaking valve. If it sat with one or both of the valves open for a long time then carbon on the exhaust, gummed up lube or simply a bit of carbon stuck between the valve and seat can cause a compression robbing leak. You can tell where this is coming from by simply listening at the intake or exhaust ports while winding the motor around to compression stroke. A hissing or whistling will tell you that compression is forcing air out somewhere.

NOTE: You will near that whistling anyway from the case vent as a normal process from the piston moving up and down, so will have to try and focus on the ports instead.

At first I did not have any compression due to a push rod not seated on the rocker arm correctly.. it was off to the side.. I corrected that, adjusted the valves to the recommended .002 clearance and now it seems to have pretty good compression.

Second and more insidious would be a result of a hard stoppage and I have ONLY seen this on a 65. A friend had me tear his down since after a boink he could not get it started. I found it had torn some cam teeth loose so the crank was turning, but the cam was not. Does rotating the crank have the rockers activate?

No clue on previous history of this engine. Somehow and I don't know how or when.. it ended up in my possession. I do know that I did not pay anything for it.. (I think) but to answer your question, yes the rockers activate (now) .. no bearing noise.. the engine seems to be in very good shape mechanically.. just needed a good antifreeze bath.. and it cleaned up very nice.



A final cause of low compression would be a stuck ring. I once added a metal conditioner to my standard After Run Oil mix as it had a pretty tenacious "Stickiness" I thought would make it bond to surfaces better for storage and protection. Worked that way quite well, unfortunately it also seemed to harden pretty good after a while. With engines stored successfully for 20 years or more with my stock 50/50 mix of ARO and Air Tool Oil, to see this occur with the second 125 in approx a year was disappointing and required a teardown to free the ring.

everything moves nice and free.. I have been using automatic transmission fluid in place of after run oil.. seems to work pretty nice and I felt good after reading Bill Robinson's piece that he did the same thing..



Last and most simple is a failed glow plug. Have you tried the plug out of the head to see if it works?

I did and it glowed bright red.. but again not knowing the history of the engine, it will be replaced before I attempt to fire the engine again..

Also the final question, how do you have it mounted? Orientation and tank height can perhaps be the problem and simple changes all that are required to solve it.

right now it is on a test stand.. I hope to mount it inverted in a Phoenix Models Decathlon, although I might put an OS 46AX 2S in that because they design the plane to keep everything under the cowl if you use the 2 stroke.. so we will see as I get closer to that project.. right now I am kitting a Sig 4 star..

Only warning I give to new 4-stroke owners is to NEVER have yourself or others in front of the engine or to the sides, especially when first setting them up. Saitos do not like to run lean and can stop on a dime once you wind them up to work on the HS needle. This frequently ejects the prop at high speed and energies.

Bill Lowen

and don't worry about thread hijacking Cougar.. at least as far as I am concerned.. I have read this thread with considerable interest and have gained a wealth of information from all of you.. I would also suggest if you guys have the time and have not done so yet.. read the complete Saito notes by Bill Robison.. That was a great read! just a little sad at the end hearing of his passing..

Cougar429

My Feedback: (3)

Bill, forgot to mention another simple check. With the throttle arm removed, set the LS needle flush with the surface. That should get you close.

On the HS needle, I believe the start is 2 1/4 turns out. With a piece of fuel tubing on the inlet, see if you can blow through it with the throttle wide open. If not you have a blockage and no amount of tweaking will allow it to feed fuel.

NOTE 1: Check the intake tube has the alloy backer ring where it fits into the head, (I frequently see that missing on used engines). That helps compress the O-Ring and ensure it seals without backing out.

If your valves close with the correct gap, you have compression, no leaks in the intake system and a good plug then you should be able to at least get it to fire off. If still difficult, pull the plug and add a few drops of raw fuel. Reinstall and see if it fires up. If momentary you at least know the problem is not mechanical.

NOTE 2: All this is assuming the cam timing is correct. It would take almost complete disassembly to confirm, but a quick check can be performed with the plug and rocker covers removed. Spin the crank with a small soft pin or other method to see when the piston reaches TDC. On compression neither valve should be open. On exhaust stroke you will see the exhaust valve start to close and the intake valve slightly open when reaching TDC.

One other factor I've found is none of mine will start with the throttle at idle. I have to sometimes open it up to just below 1/4 throttle. Mind you, none of mine retain the choke system for ease of rigging inside cowls.

If you are using an electric starter, be advised Saitos can sometimes idle below the spin RPM of a healthy hand unit and are frequently so quiet you may not know when they are self-sustaining. Both my 100's are like that.

What fuel are you using and is it fresh?

Bill Lowen

fuel is brand new.. Wildcat 15% nitro 18% Synthetic Oil

I assume I have pretty good compression.. if you stick your finger over the exhaust outlet on the head, it sucks your finger in on the compression stroke.. Can you check the compression like you do a car, with a compression gauge that screws into the plug hole.. Do they make such a thing for these small engines? and I am using an electric starter.. what you said actually happened when I fired my OS 52.. it was running and I did not even realize it.. it was that quiet.. no such luck with the saito..

I am thinking between the antifreeze bath, new seals in the carb and intake, (the alloy backer is there) and a fresh glow plug, she should fire.. hopefully I will have my parts by the weekend

Cougar429

My Feedback: (3)

If you are turning the crank the normal direction that should NOT happen. Any time the piston is rising you will only get outflow on the exhaust during the exhaust stroke, and directly following a draw on the intake as the piston then travels down.

If once past TDC on the POWER stroke and the piston is traveling downwards you feel a draw on the exhaust, then your have a leak in that valve. It may be slight and allow for compression when turning quickly, but will not help you build enough for a sustained light off.

You should be able to feel good compression even if turning slowly. That indicates good seals at the ring and both valves. You may have to inject some oil or fuel to initially help lube and seal the ring. Don't spin it completely dry.

Off to get some lunch and clean the build room. Will check back during the day. My vacation started so will be able to stay active till after the Holidays.

Bill Lowen

normal direction is counter clockwise looking at it from the front right? Maybe I need to check that again.. maybe I don't have the valves set correctly either. I am definitely getting suction from exhaust port be it on the compression stroke or exhaust stroke.. if I was turning the prop the wrong way, would I feel the suction with my finger? I know it has compression at least some because you can feel the resistance in the prop.. it just does not spin free like it did when the push rod was out of place.

also, which side of the engine is the intake and exhaust valve?

hsukaria

Bill, if looking at the engine witht the propeller end facing you (carb is facing away), the prop should rotate counter-clockwise. The exhaust valve is on the same side as the exhaust port and muffler (left side with prop facing you).

If flipping the prop the wrong direction, you would still feel suction and compression.

Also, maybe it was mentioned before, but I would use a new(er) glowplug. A Fox Miracle plug or an OS type F. There are other brands, but should be the 4-stroke type.

Bill Lowen

duh.. I guess that makes sense.. of course the exhaust valve is going to be on the side of the exhaust port.. guess that was dumb question..

I was pretty sure it was counter clockwise which is the direction I have my starter going.. so if I was going in the right direction (counter) would I feel suction from the exhaust port? I was thinking I should..

Cougar429

My Feedback: (3)

No suction on the exhaust port, only a burp when on the exhaust stroke. Check to see you are turning the right direction, (easy to do if the battery connections are reversed). If not, that would explain why it won't start.

If turning the right direction and still getting that vacuum on the exhaust then your cam timing has to be out. Unfortunately, that will require pulling the cylinder to lift the cam housing and check the alignment of the notch on the crank gear, (also in line when the piston at TDC) and the dot on the back of the cam gear. They should go together.

Bill Lowen

OH OH!!

OK.. lets just say hypothetically.. if one just decided to try to start an engine with an electric starter without pulling the rocker covers to ensure the pushrods were making good contact with the tappets.. and said exhaust pushrod was not allowing the exhaust valve to open and close.. that would mean in the course of the spinning of said engine, only the piston and intake valve were moving.. said engine would no longer be in time necessitating the above mention of the procedure of removing the cylinder and resetting TDC. and of course I said hypothetically because nobody is that stupid as to of done that in reality.. especially yours truly..

Did I mention that I really have no money invested in this engine so this really could be a great hands on learning opportunity? That would be whats called "the silver lining"

Cougar429

My Feedback: (3)

The exhaust valve sticking open could account for what you describe AND a no start condition. You will feel a draw during the power stroke as this is the only downward part of the cycle where the intake valve is closed.

If any valve will stick, it's usually that one. Carbon/fried lube buildup on the stem can make it bind up, usually when it sits with the valve held open. The same buildup between the valve and seat can prevent a good seal.

Learning is good. Even better when it's free.

hsukaria

Cougar429, if it is just a sticking valve, could Bill just soak the engine in penetrating oil and manually push the valve stem up/down until it frees up? Might work.

Bill Lowen

everything is moving freely now.. just concerned the engine is not in time..


That was my question.. if the engine is spun and only the intake valve and crankshaft moves, would the engine be put out of time.. if that makes sense..

hsukaria

Yeah, as you rotate the crankshaft 720 degrees (2 revolutions) , the intake valve has to open as well as the exhaust valve. If either valve is not opening and closing in a span of 2 revolutions, you got problems.

Bill Lowen

well I guess that explains the no start... no worries.. looks like I have some reading and work to do.. sure wish I could find a step by step service manual for this thing.. if anybody has a tear down step by step PDF and want to share, I would be mighty grateful.. probably go back to the step by step in Bill Robison's Saito notes..

at this point I think I just need to go in and reset TDC.. that does not seem like too big of a task