Welcome to Club SAITO !
09-02-2020, 02:24 PM
Care to educate me?
Slop would the outcome either way, be it bad geometric tolerances or shabby parts.
I am not inferring Saito intentionally made the slop, It is you who assumed they did.
Been doing this far too long to be baited into an argument with you. Worked with fitting and assembling. bearing setups from these toy engines to precision machine spindles to huge metalworking press bearings.
All good designs also specify the shaft and housing fit as well as the class of internal bearing clearances. Those clearances allow for the changes that take place when interference fitted on shafts and into housing bores.
Geometric Dimensioning and Tolerances is the actual, accepted practice. Properly applied, that .006" to .008" you prefer would be the final result, nothing outside that range.
All of that aside,back to the original thrust of my first comment;
In this application, a properly installed bearing should be seated with its outer race against the shoulder of the housing bore.
Go ahead, ignore that. Look for what you "want" .
Just like trying to explain the cam lobe position to you, I am done.
Slop would the outcome either way, be it bad geometric tolerances or shabby parts.
I am not inferring Saito intentionally made the slop, It is you who assumed they did.
Been doing this far too long to be baited into an argument with you. Worked with fitting and assembling. bearing setups from these toy engines to precision machine spindles to huge metalworking press bearings.
All good designs also specify the shaft and housing fit as well as the class of internal bearing clearances. Those clearances allow for the changes that take place when interference fitted on shafts and into housing bores.
Geometric Dimensioning and Tolerances is the actual, accepted practice. Properly applied, that .006" to .008" you prefer would be the final result, nothing outside that range.
All of that aside,back to the original thrust of my first comment;
In this application, a properly installed bearing should be seated with its outer race against the shoulder of the housing bore.
Go ahead, ignore that. Look for what you "want" .
Just like trying to explain the cam lobe position to you, I am done.
I wrote post number 47713 to confirm Dave's assertion that pulling in the rear bearing by tightening on a prop WILL NOT fully seat the rear bearing fully into its bore.
BTW, the shot at me for not just taking your word on the topic of twin camgear housing geometry, from a different website even, is totally uncalled for.
09-02-2020, 03:12 PM
Not off course here. In typical loaded operation the REAR bearing takes up the bulk of the axial thrust, It does just that with the crank web shoulder in contact with the rear face of the inner race That is how they work.
The inner race on the front bearing is firmly clamped between the front shoulder of the crank and the drive collet. It is the front bearing that is designed to allow the front bearing outer race to "float" in order to accommodate any expansion differential.
This results is more stability between the crank, rod and piston assembly, in the case of Saito, the cam, gears and lifters get some help as well.
Sorry Lonnie,
The comment was not meant as a shot, just an example. As you said there, you need to check it out further. I was in agreement. Just don't care to argue.
Perhaps I misunderstood.
The inner race on the front bearing is firmly clamped between the front shoulder of the crank and the drive collet. It is the front bearing that is designed to allow the front bearing outer race to "float" in order to accommodate any expansion differential.
This results is more stability between the crank, rod and piston assembly, in the case of Saito, the cam, gears and lifters get some help as well.
Sorry Lonnie,
The comment was not meant as a shot, just an example. As you said there, you need to check it out further. I was in agreement. Just don't care to argue.
Perhaps I misunderstood.
Last edited by Jesse Open; 09-02-2020 at 03:24 PM.
09-02-2020, 03:25 PM
My Feedback: (27)
Saito 120 dual plug
First, I would like to say prayers from our family to Dave’s family.
Today I got the exhaust pipe from Gary and the muffler is from Dave. Thank You both!
I bought this engine as a parts engine on RCG. The price was right. The person I bought it from told me he had tried to run it, but it would only run at high speed. When I received the engine, I could tell it had been cleaned in something that turned it dark grey. I opened it up and there was some orange/brown goo inside it. The screws holding the cylinder to the case had been coated with blue loctite, a little heat help them get freed. I pulled the cylinder/head off and it didn’t look like it was a high use engine. I totally disassembled everything and gave it a bath in an ultrasonic cleaner. I cleaned the valves by spinning them at low speed in a drill press and using Scotchbrite on them. This engine was starting to look like it could be saved. The cam cover was broke where the set screw goes. That I just replaced. It was missing one of the washers that goes on each side of the cam. Tower was out of stock, but Lonnie found them for me at Graves RC. The backplate was the type for using the Saito pump system. One corner was broke so I just replaced it with a standard backplate. I replaced a lot of the screws just because I had them here. The valve covers are scuffed and if I wanted to make it look a little more pretty, I would replace them. I will look for a set at the swap meets once they start up again.
I ran it today on the stand with my 3% nitro home brew and got a rich high end of 8700 on a Master Airscrew 16X6. I’m sure I could have pushed it harder, but my thought was I should run it on the rich side to let everything seat back in after reassembly. It will idle forever at 1900 RPM. I love the sound with the old-style muffler. I’m thinking on pulling the engine I have in a scaled up BUSA stick and putting this engine in it for a few test flights. It sure runs sweet.
I read this thread almost every day. I’ve learned a lot from this nice bunch of guys and enjoyed some of the humor here. I hope I can return the favors done for me here.
Pete
09-02-2020, 03:43 PM
Wow Pete,
That didn't take long at all. The old Fathead is a loveable engine for certain. The carb is amazing! Thanks for the follow up.
Can you use an intact rear cover? Pretty sure I have one. For certain I can send you a pair of breather check valves.
That didn't take long at all. The old Fathead is a loveable engine for certain. The carb is amazing! Thanks for the follow up.
Can you use an intact rear cover? Pretty sure I have one. For certain I can send you a pair of breather check valves.
09-02-2020, 03:58 PM
My Feedback: (27)
Gary,
Thanks but I have a standard back plate on it now and it works fine. I just replaced the entire back set up for the Saito pump system with a regular one. Years ago I tried that Saito tank pressurizing system and didn't care for it so I was not about to even think about it on this engine. This engine starts very easy, the carb was easy to set up and the transition is great. I'm going to try to get some flight time on it this weekend. I also want to try a plug experiment with this, I have a couple of card of Fireball Hot plugs that I want to try. I ran one in my 56 and it worked as good as a FS plug there.
Pete
Thanks but I have a standard back plate on it now and it works fine. I just replaced the entire back set up for the Saito pump system with a regular one. Years ago I tried that Saito tank pressurizing system and didn't care for it so I was not about to even think about it on this engine. This engine starts very easy, the carb was easy to set up and the transition is great. I'm going to try to get some flight time on it this weekend. I also want to try a plug experiment with this, I have a couple of card of Fireball Hot plugs that I want to try. I ran one in my 56 and it worked as good as a FS plug there.
Pete
09-02-2020, 04:31 PM
Not off course here. In typical loaded operation the REAR bearing takes up the bulk of the axial thrust, It does just that with the crank web shoulder in contact with the rear face of the inner race That is how they work.
The inner race on the front bearing is firmly clamped between the front shoulder of the crank and the drive collet. It is the front bearing that is designed to allow the front bearing outer race to "float" in order to accommodate any expansion differential.
This results is more stability between the crank, rod and piston assembly, in the case of Saito, the cam, gears and lifters get some help as well.
Sorry Lonnie,
The comment was not meant as a shot, just as an example. As you said there, you need to check it out further. I was in agreement. Just don't care to argue.
Perhaps I misunderstood.
The inner race on the front bearing is firmly clamped between the front shoulder of the crank and the drive collet. It is the front bearing that is designed to allow the front bearing outer race to "float" in order to accommodate any expansion differential.
This results is more stability between the crank, rod and piston assembly, in the case of Saito, the cam, gears and lifters get some help as well.
Sorry Lonnie,
The comment was not meant as a shot, just as an example. As you said there, you need to check it out further. I was in agreement. Just don't care to argue.
Perhaps I misunderstood.
I have proved my theory (to myself) that the crank slides in the inner race of the rear bearing to accomodate thermal expansion of the case in these three ways:
1. As previously mentioned, I have measured the distance between the front and rear bearing bores, the distance between the front and rear shoulders of the crank and factored in the difference in bearing thicknesses. The resulting number equates to a gap between the rear bearing and crank shoulder.
2. With front and rear bearings fully seated and crank, collet and drive flange installed I heated the case to approx 300°f and lightly tapped the rear of the crank. The front bearing moved forward in its bore indicating that even though the case was quite hot there was a gap between the rear bearing and the crank shoulder which was taken up when I tapped on the the rear of the crank.
3. A feeler gauge between the rear bearing and the rear shoulder of the crank. If the bearings were preloaded any amount I would not be able to get a feeler gauge in there.
I am very confident in my measurement methods and just fail to see where any manufacturer would elect to forcefully push out and withdraw a press fit front bearing during thermal expansion and contraction of the case instead of just allowing the crank to slide in and out through a slip fit rear bearing. Sorry friend, I think I'll stick to my guns on this one.
09-02-2020, 04:53 PM
Hey Pete, congrats on getting that old girl running. I'm jealous, you're getting better numbers than I am.
Everyone here knows what a power monger I am.
I completely disassembled and cleaned my fathead carb and set the midrange dial to the factory reference line on the carb body. Did you have to mess with the midrange adjustment of the carb or did you just leave it?
Everyone here knows what a power monger I am.I completely disassembled and cleaned my fathead carb and set the midrange dial to the factory reference line on the carb body. Did you have to mess with the midrange adjustment of the carb or did you just leave it?
09-02-2020, 05:06 PM
The manufacturer is quite aware that under operating conditions, as designed, the primary operating thrust load is on the rear bearing , radial load as well, hence the larger size. That load is best delivered shoulder to shoulder, not thru a linear slip along the shaft, period. Your static feeler gauges dont tell the story. Tap that shaft forward, the front bearing moves forward, the crank shoulder is seated on the rear bearing inner. That is how it works.
By following your supposition, that load would have to flow through the smaller forward bearing.That bearing of course has no forward retainer on the outer race (for reasons I already explained). The forward bearing has the inner race captured between two shoulders to allow it to float the front bearing. The front bearing at operating temps can indeed move as needed.
Stick to your guns, you are still incorrect. So I agree only to disagree. Too much real experience and schooling for me to agree.
By following your supposition, that load would have to flow through the smaller forward bearing.That bearing of course has no forward retainer on the outer race (for reasons I already explained). The forward bearing has the inner race captured between two shoulders to allow it to float the front bearing. The front bearing at operating temps can indeed move as needed.
Stick to your guns, you are still incorrect. So I agree only to disagree. Too much real experience and schooling for me to agree.
Last edited by Jesse Open; 09-02-2020 at 05:15 PM.
09-02-2020, 05:19 PM
The manufacturer is quite aware that the primary operating thrust load is on the rear bearing , radial load as well, hence the larger size. By following your supposition, that load would have to flow through the smaller forward bearing.That bearing of course has no forward retainer on the outer race (for reasons I already explained). The forward bearing has the inner race captured between two shoulders to allow it to float the front bearing. The front bearing at operating temps can indeed move as needed.
Stick to your guns, you are still incorrect. So I agree only to disagree. Too much real experience and schooling for me to agree.
Stick to your guns, you are still incorrect. So I agree only to disagree. Too much real experience and schooling for me to agree.
09-02-2020, 05:36 PM
My Feedback: (1)
oh Dave I am so very sorry to here of this. I know I can not help, but I wish so much that I could !
I don't think think this well help much, but I under stand the pain. my own brother live the hard drug life, he died at 17, but the night he died he was clean of drugs, he took my mother's car without knowing how to drive and he had an accident.
God Bless
Jim
Last edited by the Wasp; 09-02-2020 at 06:07 PM.
09-02-2020, 05:54 PM
My Feedback: (27)
Lonnie
I left the mid settings right in the center. Transition is very nice on this engine. I took another engine out of a plane that I am going to test fly this one on. For that plane I fly it mostly at 1/4 throttle so that will be the final test to see if I have it set up right. If you have ever seen the Balsa USA stick or it used to be called a Swizzle Stick I scaled one up 1.85 times and use it as a test plane. I can fly it so slow that in a good breeze I can make it stand still in the air. Twice I have gotten it to fly backwards in the wind. If the weather is good on Friday or Saturday it will be in the air. It has a high lift flat bottom airfoil with almost 1900 square inches of wing area. It flies like a big trainer.
Pete
I left the mid settings right in the center. Transition is very nice on this engine. I took another engine out of a plane that I am going to test fly this one on. For that plane I fly it mostly at 1/4 throttle so that will be the final test to see if I have it set up right. If you have ever seen the Balsa USA stick or it used to be called a Swizzle Stick I scaled one up 1.85 times and use it as a test plane. I can fly it so slow that in a good breeze I can make it stand still in the air. Twice I have gotten it to fly backwards in the wind. If the weather is good on Friday or Saturday it will be in the air. It has a high lift flat bottom airfoil with almost 1900 square inches of wing area. It flies like a big trainer.
Pete
Last edited by modeltronics; 09-02-2020 at 06:10 PM.
09-02-2020, 06:03 PM
You are "surmising", assuming and even conflicting.
I am relating accepted design and building practices garnered from real schooling and decades in the trades.
In the machines I have serviced, to manufacturer supervised spec. As with machines I have designed, those are the principles and standards that were and are followed. When running, I build for that rear inner race to abut with the crank face and the rear inner solidly seated in the bottom of its bore. No room for feeler stock.
Like I said, we can agree to disagree. Not a problem
I am relating accepted design and building practices garnered from real schooling and decades in the trades.
In the machines I have serviced, to manufacturer supervised spec. As with machines I have designed, those are the principles and standards that were and are followed. When running, I build for that rear inner race to abut with the crank face and the rear inner solidly seated in the bottom of its bore. No room for feeler stock.
Like I said, we can agree to disagree. Not a problem
09-02-2020, 06:06 PM
No mother should ever have to bury a child.
Or Grandparent console a broken hearted Daughter.
09-02-2020, 06:15 PM
My Feedback: (1)
hey Pete, that twin Plug'er you got there ! something to know here. my friend had that twin Plug'er Saito 130 Twin (pistons) and he ran 2 different plugs on each head, one hot and one medium on each head. maybe that will give you something to try 
Jim
Jim
Last edited by the Wasp; 09-02-2020 at 06:18 PM.
09-02-2020, 06:39 PM
Lonnie
I left the mid settings right in the center. Transition is very nice on this engine. I took another engine out of a plane that I am going to test fly this one on. For that plane I fly it mostly at 1/4 throttle so that will be the final test to see if I have it set up right. If you have ever seen the Balsa USA stick or it used to be called a Swizzle Stick I scaled one up 1.85 times and use it as a test plane. I can fly it so slow that in a good breeze I can make it stand still in the air. Twice I have gotten it to fly backwards in the wind. If the weather is good on Friday or Saturday it will be in the air. It has a high lift flat bottom airfoil with almost 1900 square inches of wing area. It flies like a big trainer.
Pete
I left the mid settings right in the center. Transition is very nice on this engine. I took another engine out of a plane that I am going to test fly this one on. For that plane I fly it mostly at 1/4 throttle so that will be the final test to see if I have it set up right. If you have ever seen the Balsa USA stick or it used to be called a Swizzle Stick I scaled one up 1.85 times and use it as a test plane. I can fly it so slow that in a good breeze I can make it stand still in the air. Twice I have gotten it to fly backwards in the wind. If the weather is good on Friday or Saturday it will be in the air. It has a high lift flat bottom airfoil with almost 1900 square inches of wing area. It flies like a big trainer.
Pete
09-02-2020, 07:32 PM
My Feedback: (27)
Here is my test plane. 8 foot of wing with a 19 inch cord. I did the CAD files for the ribs. All you have to do is send the files to Balsa USA and they will laser cut them for you. Everything else you can make on a table saw or a band saw. It will fly with any FS engine from 80 to 120. It is a very simple plane but great for testing engines. Since it is a slow flyer I sit in a lawn chair while flying it. To make it even more relaxing note the speaker on the side of my field box. I can listen to my old Beach Boys music while I fly.
09-02-2020, 07:43 PM
My Feedback: (27)
Jim
I want to test some plugs I got at a swap meet. I bought two cards of plugs called Fireball Hot. I remember these plugs from when I was a kid flying CL. I tested one in a Saito 56 and it ran as good as an F plug. So, I am interested in how these will work in this engine.
Pete
I want to test some plugs I got at a swap meet. I bought two cards of plugs called Fireball Hot. I remember these plugs from when I was a kid flying CL. I tested one in a Saito 56 and it ran as good as an F plug. So, I am interested in how these will work in this engine.
Pete
09-02-2020, 07:53 PM
09-02-2020, 11:24 PM
Dave i will add an australian prayer to the american one's here and wish you and your family the best and perhaps some peace in the coming days, plus i was wondering if you can help me with a small problem i'm having here. I've been reading gary and lonnie's opinions back and forth about bearings and, lord help me, it's like reading a spanish to english translation of a bultaco trials motorcycle owners manual, hoping some time in the future you can shed some light on the issue although i'm on gary's side because his avatar is better. Take care now.
ps pete flying while listening to music sounds good
ps pete flying while listening to music sounds good
09-03-2020, 04:32 AM
The Fathead was only offered as a single plug engine as far as I know. I missed that you said it was dual plug earlier this week. My bad.
The fathead 120 has an enormous cylinder that overhangs the camgear housing and a uniquely designed airbleed carb with a midrange adjuster dial.
Your engine is called an FA-120S DP.
The fathead 120 has an enormous cylinder that overhangs the camgear housing and a uniquely designed airbleed carb with a midrange adjuster dial.
Your engine is called an FA-120S DP.
Last edited by Glowgeek; 09-03-2020 at 04:41 AM.
09-03-2020, 08:28 AM
The lovely Fathead along with some FA-120 standard an dual plug versions for comparison.
The fatheads are becoming sought after by gasoline conversion types. The prefer the added fin area. The multi adjustment carb could be another plus.
Top views
Fathead and FA-120
The fatheads are becoming sought after by gasoline conversion types. The prefer the added fin area. The multi adjustment carb could be another plus.
Top views
Fathead and FA-120
Last edited by Jesse Open; 09-03-2020 at 08:36 AM.