Ken6PPC

The only things I can think of to tell you are:

First, relax. It ain't that hard to do!

Second, if you don't need to change the ring, leave the piston in the cylinder. If you remove it, the ring has to "seat" again.

Third, the hardest part is getting the timing set correctly when you put it all back together. No, that is wrong. It isn't hard to do, but it IS unnerving if you have never done it before.

It helps a lot if you take some time to understand what is supposed to happen when, so you can check timing before you put it all back together. Before you remove the cylinder and piston, take a few moments to study how the valves act when the crankshaft pushes the cylinder all the way to the top. Take note of when the intake valve and exhaust valve opens and closes. When you understand how the valves operate, it is much easier to be sure the timing is correct before buttoning everything up. To do this, remove the carb, the rear cover and the valve covers. Rotate the crankshaft and watch what is happening to the valves. I took some pictures a while back, and posted them here:

http://www.rcuniverse.com/forum/fb.asp?m=7442072

Last of all, relax! If you run into any area where you aren't certain what to do, ask the engine gurus here on RCU. (Not me, but the REAL engine gurus.) They will be happy to help you!

GarySS

My Feedback: (13)

Hi Fellow Saito-owners, Subject: Sounds from the Propeller and/or engine.........
Just got back from the field after 3 flights with my Saito .82 on a GP Reactor. I'm using an APC 14x4W prop and 15% nitro. I'm using the Reactor as a mule to break-in the Saito for another model, a profile. So I am going full throttle in giant loops, vertical climbs and just general boring holes at various throttle settings. When running up to full throttle on the level I am getting a building "whine, moan, revv" sound, like of like that of an open wheel Formula 1 racing car on a straight away. It actually sounds like a full-scale aerobatic plane when doing some maneuvers and it is neat. BUT, is this actually doing some harm somehow?

After a few runs like this I can't tell that there is any problem, the engine is running like a champ. Any opinions? Surely I'm not going ballistic with the prop tips!!!

w8ye

My Feedback: (16)

Enjoy.

That's the way it is with a large diameter low pitch prop. Not hurting anything

RPMcK

My Feedback: (1)

Gary,

I would think that unless you are under-proped for that engine /airplane conbination you're probably not hurting anything. If you set things up using a tach. and know that your static RPM is such that the engine is not likely to seriously exceed redline (rated RPM) when it unloads in the air it's probably OK to just enjoy the neat sound of a full throttle flyby. It would be fun to know what the prop tip speed is however. Must be a formula for figuring that out. I don't know but I'm sure one of the other guys do. I'm sure you'll be getting other comments. Enjoy your day!

Ron

rlmcnii

My Feedback: (3)

RPM,

If one would: Pi x prop diameter (inches) x rpm, divide this product by 720, one should arrive at prop-tip speed in feet-per-second. I think[sm=confused_smile.gif]

GSS,

When in the air at the same time as two-strokes, my Saitos always make me think of a Ducati twin on a track full of 4-cylinder rice-burners. The rice-burners may be, and usually are, faster. But,.....to which would you rather listen?? Me too!

Michaelh

My Feedback: (4)

Your hitting high Rpm's up in the air. Save the full throttle for uplines, I just tuned a new .82 in last night and hit 10,200 on that prop . Im using another .82 with the 14x4w on 30% with a turbo Header and hit 11,000 rpm with it.
Ill more the likely do some test with the 15x4w in a little bit and also compare the engine with the Turbo Header to it using the stock exhaust.

RPMcK

My Feedback: (1)

rlmcnii,

since we really don't know what rpm the engine in question is turning, i guess the next question is, what rpm would our Saito's have turn to put the tips of a given prop supersonic? i know (i think) that the formula you gave can be used to solve for that too. i just don't know how to do it. (rearrange the formula that is) i'd really be interested in knowing if our engines could really spin a porp that fast. anyone actually know?

Ron

rlmcnii

My Feedback: (3)

RPM,

1100 feet-per-second (approx Mach 1 at sea-level) requires a little over 18000 rpm with a 14" propeller......I think.

RPMcK

My Feedback: (1)

Thanks guy, for doing the math for me. Can't ask for more than that. Sorta indicates there is probably not much chance of our Saitos putting prop tips "ballistic" but man they sure make 'em sound good!! Have a great day.

Ron

mbrennan1

Me again. Does anyone know of any web pages I can refer to for detailed instructions on how to change the bearings in my 125? I have looked and have not had much luck. My bearings should be here tomorrow and want to get it done. Also, is there anything special I need to do the first time running after replacement?

phippsa3

My Saito 125 is pulling my 1/4 scale Cub around at the minute. Will almost take it vertical at full chat.
Idles smoothly at 1900 rpm. Think i have an APC 16/7 on it at the minute though i would have to check.

Have the 82gk, the 91s and the 125. Would have to say the 125 is my favourite at the moment.
82gk is going into a 58" FW190 here http://www.rcuniverse.com/forum/m_7644885/tm.htm

Here is a video of my Cub with the 125 in it http://uk.youtube.com/watch?v=VGg6XvOD9jI

beaver180

My Feedback: (10)

Nice vid, thanks for sharing with us. Better try to get one of the Citabria with the 180 in it now...

Paul

phippsa3

Really tempted to put a SAITO FA-182TD twin cylinder engine into it. Would sound great.

beaver180

My Feedback: (10)

When I did my 150 bearings a couple of weeks ago I gave the engine a good clean using a tablespoon of dishwasher power in 2 pints of boiling water ( came up a treat, don't forget to rinse it well after cleaning ) while it was apart.

I lubed the bearings and internals ( including tappets and push rods ) with a drop or two of straight cool power syn 2 stroke oil before re assembling.

When I ran it the first time afterwards I ran it rich ( sort of like when running in ) for a short time. Now runs like a dream, just goota find a model to put it in [] maybe my vintage CAP 21 with 76inch wings??

Cheers, PAul

Ken6PPC

These videos show how to disassemble a 2S, but a 4S is similar. The only real difference is, with a 4S, you have to concern yourself with getting the timing right when you put the cam back in. My earlier response to you should help there.

Xjet put these videos together:

http://www.youtube.com/watch?v=TuzEco3EDUM

http://www.youtube.com/watch?v=OLSoXPLGzOI

I think they are excellent "how-to" videos!

Ken6PPC

Oh yeah. It is smart to keep the push rods identified, so you can put them back in the same place they came out of. I put mine in a baggie, with "exhaust" or "intake" written on it. The tops are different than the bottom of the push rods too, so I mark the tops with a piece of tape.

As I mentioned earlier, leave the piston in the cylinder, with the connecting rod attached. Before taking it off the crank, be sure to mark the connecting rod on the side closest to the back cover. That way, you can be sure you put it back on the same way it came off.

One guy here suggested taking digital pictures as you disassemble your engine. That would be helpful when you start to put it back together.

Again, relax, take your time, and ask here if you don't understand something. Changing bearings isn't hard, but you do have to take it one step at a time.

mbrennan1

Thanks for all the info. I am sure it will go fine. I just don't want to ruin anything.
Thamks again, I'll report on how it went.

mike boxtall

For all you out there with 125's, does 85-8600 with a 14X10apc on 15%coolpower fourstroke fuel sound about right? As I was playing with the needles on a lean setting it would jump up to around 9000 then bog down to around 8400. But between 85&86 it was humming along real nice with no coughs or sputters. Transition is good also from the low end to high end. Still blowing enough smoke so that you would be able to see a faint trail in the air. Sounds about right?

w8ye

My Feedback: (16)

Sounds about right.

Other props are 15-8, 16-6, & 17-4 depending on the plane and your style

mike boxtall

Plane is a GP Little Toni. I tried the 15X8 and didn't like it, rpms were down to 81-8200 and the engine just didn't seem as happy with it either. The other prop I have for it is a 12X12, once I get my thumbs back with this prop. I have not run it yet with the 12X12 so there might be some more playing with the needles. Also the engine has been sitting for well over a year and was barely broken in when my last Toni met its demise. I have only about 2 maybe three jugs of fuel run through it. Is it broken in or should I still be taking it easy?

w8ye

My Feedback: (16)

It is broken in

mike boxtall

Thank you.

mike early

Do you still use the 15-6 on your 125?
I've gone to the 15-6 prop when using a 2-blade.
I broke my 15-6 APC and bought an Evolution 15-6 prop. Performance seems identical between these two props.
I get about 9400RPM and it seems to be a sweet spot for this engine. Good performance.

w8ye

My Feedback: (16)

Now that my 125 is broken in, the 15-6 doesn't seem like enough prop. I changed to a 16-6.

I have a Magnum 120 that I use a 15-6 on.

flyingbells

Hi folks,

I've got a Saito 100 "bad boy" that likes to chew up spinners and chuck props (back fires). Its compression is super strong, ie: takes quite a bit of effort to turn it with a prop on, and only the dynatron type starter can spin it up. Is that normal?

I've been propping it with APC 14x6, done about 1 gallon of fuel so still quite new.

Thanks for suggestions.