Rudolph Hart

Nice one earl.There must be a forward vortex going on somewhere ed,if i run an engine uncowled and no crankcase breather hose attached i get oil on the back of one prop side only,any thoughts?

Am going to make a stubby exhaust for my 220 and run a perry vp20 pump,anybody here have experience doing that,i think dave said ages ago that he had a japanese factory pump that only they get for some reason.

w8ye

My Feedback: (16)

The Saito factory pump is an adjustment nightmare. You can never get it right as you change engine speed, you have to adjust it all over again.

Use the VP-20

earlwb

Thanks guys, Yeah it was a cheap thrill to get it correct the first time. The new bearings were very friction free, I had to stuff a rag into the crankcase to keep the crankshaft from instantly rolling to BDC when you barely touched the crankcase or crankshaft with the camshaft assembly.

Here is a boring video of me running the old Saito FA80 engine on the test stand.
[youtube]http://www.youtube.com/watch?v=HfpKf6RqkIs[/youtube]

spaceworm

I am glad you admit that watching a video of an engine just running at one speed is like watching grass growing. At least, one could vary the rpm, show it being started, or something more than just running. Same with videos of planes flying. Having them just fly around in a racetrack pattern for six minutes is boring, you just keep waiting for something to happen and nothing does. JMTCW.

Sincerely, Richard

earlwb

I wanted to make sure that those who don't want to watch the video can have a chance to avoid it.
I did vary the RPMs from low speed to WOT a number of times and I used a tach showing some typical RPMs that I was getting.
It isn't like it was a control line engine being run for 5 minutes straight on the video clip.
Although watching a engine turn some incredible amazing RPMs for a couple of minutes is interesting as you are wondering when that sucker is going to blow up or something.

scubajohn

hi guys i am new to the saito famly with 3oo twin daul carb with a few questions
 
I bought it to go on a waco 1/5th scale 72'' wing span but have ben told its to big for the waco so now i think i will build a large ugly stik how large should i build it

also the left carb is pushed in bent intake manifold i think where would i get one do i need one it is just in a little or is this the norm

what would be a good prop 20 x 5 me thinks

w8ye

My Feedback: (16)

Here you go

http://www.horizonhobby.com/Products...=SAI300TTDP103

The 20 X 8 prop would be ideal or a 18 X 10 if you do not have the ground clearance

RC-CAKES

My Feedback: (4)

Can anyone help me with a subborn Saito 72?!?! I have had this engine for a few years. It has run okay. Picked it up lightly used in a 40 size biplane. It always has been a bit hard to dial in. You can get the idle set- but it has a little surging effect that I can't figure out. I finally got fed up and pulled it out of the plane and onto my snazzy engine stand.

I am not a newbie to saitos- I have a 100 and 125 that run great. No issues at all. This just escapes me///
SO I tried to do some tuning to start from the begining Here is what I have done thus far:

Engine has great compression - clean in & out; pulled the carb off to look at throttlebody/intake gaskets - all ok. Bearings feel/sound fine.
New plug (OS F); new gas Omega 15%; regapped the valves - all were fine but reset anyway.
4 turns to HS open - opened LS a turn or so.. its going to be rich! I live at 5800 ft MSL

Fires up - I let it warm up. Leaving glow power on - run to full throttle. 12x8 evolution prop; 8500 or so RPM.. slowly (10-12 sec) lean in small increments. Peaks at 9850 (or so) I richen to drop 400 rpm. She won't hold the rpm. it just wonders 100-300+ rpm. If you richen it back up to start over finding the peak - it can bog down... and take a min or so to wind back up. Once peak-400 is 'set'; Slow to idle.
It was comfortable at 2800-3000 rpm but a bit rough. I lean the LS slowly waiting for the response. I work it to where it will start to stumble.. and then back up some where it idles smoothly. I let it idle for a few minutes. It seems ok. Even goose it to WOT - and it responds fine - just still hunts on the rpm at mid-full throttle - nothing steady. Pinch test at idle - rpm rises..then stumbles>>> set correctly, right?

Back to idle- I remove the glow power - boom dead. I figure, too rich. So I restart and lean the LS some and remove. dead! A little more and its ok. 2800 RPM idle (seems too fast) but she gets rougher less than that. I am thinking now that it is running on it own glow- I will reset since it is probably richer. I go full power - retune to find peak.
Still hunting rpm. I set peak - 400ish.. Idle back slowly.. and she dies about mid throttle!!!

Carb?? AIr leak? Wouild that new carb kit from horizon be any help (the new improved gaskets, etc kit)??

AGGHHH/. I am done for the day. I read the saito notes <sticky>; my Engine guide by David Gierke book; the saito online site.. What am i missing? Is this why the guy sold the plane?!?!

Thanks for your help here.

w8ye

My Feedback: (16)

Saito 72 engines leak vacuum at the junction of the intake manifold and the head.

The root of the problem is the plastic back plate that must be replaced and a new O ring put on the intake manifold

RC-CAKES

My Feedback: (4)

Interesting!!

Can you replace it with a non-plastic one? Or is plastic all there is? Does the backplate 'give' and allow movement in the intake/head location?

Does the FA-82 have the plastic back and same issues as well?

Thanks for the fast reply!

w8ye

My Feedback: (16)

The plastic back plate will flex, warp, etc so the intake pipe vibrates in and out where it goes into the head thus wearing out the Oring at that point.

The only new back plate available is an aluminum one.

You will also need a back plate gasket and the Oring seal for the intake manifold

http://www.horizonhobby.com/Products...rodID=SAI82B17 This is the new back plate

http://www.horizonhobby.com/Products...rodID=SAI8091B This is the Oring for the intake

You will have to make a gasket to go under the new back plate. I cut one from the cover flap of the package that the back plate came in or pay $4.50 for one..
Engine Gasket Set: AB
$4.50[SAI82B32]

You will also need this screw set to attach your carb to the new back plate because your old screws are sheet metal screws and will not work.

http://www.horizonhobby.com/Products...rodID=SAI91S90

Some of these parts are from other size Saito engines but that is what it takes to put the new aluminum back plate on the engine.

Note that the Saito 72 and Saito 82 crankcases are the same size around the back plate and the parts are common.

RC-CAKES

My Feedback: (4)

Awesome! Just ordered those parts! Looking forward to getting this engine purring! Thanks so much for the links and advise. Love this place!

Will report when it's installed.

Thanks again.

Rudolph Hart

Hi all i've yet to have a problem with the plastic backplates yet,they are extremely rigid and will take a lot of heat.Rotorwing it sounds like you have the lsn a smidge to lean mate,hope you richen up a bit.

earlwb

As I remember it, the plastic backplate was a problem if used on profile types of airplanes, such as the 3D profiles for example.
So if your own airplane's design was such to help keep the vibration levels down, then you shouldn't have a problem.
The profile airframe tends to allow for more vibration to occur. That extra vibration was enough to cause the plastic backplate to leak, warp, and actually wear down. There was a guy who custom made CNC aluminum backplates for a while, but since we can buy metal ones from Saito now, I don't think he makes them anymore. It might be mentioned way back a couple of thousand messages ago in this thread here.

Craig 01

Partially correct,it was actually the vibration/movement of carb on the semi rigid plastic back plate (even with correctly tightened cap screws) and hence the inlet tube moving in and out of the inlet port wearing/chaffing or cutting the inlet tube o-ring with resultant inlet leak mainly on profiles as mentioned previously.The back plate to crankcase seal has no effect on the 72 and 82 A models performance other than blow by oil leakage usually as a result of loose or overtightened screws warping the plastic back plate and being a separate issue.Both issues corrected by fitting the aluminium backplate linked to by w8ye previously.

w8ye

My Feedback: (16)

Those of you wanting plastic back plates, they are no longer available from Saito.

But I have a half dozen warped, bent, and flexible plastic ones if you are so inclined.

mschulz531

Thanks for the offer...but I'll pass. I've already purchased a metal backplate (and O-rings, etc) for my SA-72.
In fact, I'll add my old plastic back plate to the offer - free to any interested party!

blw

My Feedback: (3)

They will also vibrate loose on a test stand or in a built up model, with or without over tightening. Mine came without washers so I added those. I finally stopped the vibration issue by using epoxy as a thread locker on the backplate bolts, and by putting a sealing ring of RTV under the metal washer that holds the viton o ring in place at the end of the manifold pipe. Black RTV looks better than orange.

I learned the hard way to check the vent line too because a collapsing fuel line will give almost the same symptoms.

But, I'm still buying that metal backplate and screw set that Jim looked up!

mschulz531

That screw set is not really necessary. I went to my LHS and bought a small pack of 2.5mm or 3mm screws (don't remember which) and they worked just fine. The LHS had the screws with all their R/C car supplies (they are somewhat light on R/C airplane supplies).

Really appreciate the paper gasket idea...I'll have to craft one of those this weekend.

Quikturn

My Feedback: (12)

Hello all,

I have a Kyosho P-40 with an inverted Saito 65 in it (both of which I've owned since new) but I'm having headaches getting it to run right. The engine has been broken in according to the instructions and runs well on the ground. In the air it runs well with the cowl off but that's not how I want to fly it. I realized it may be overheating with the cowl on so I restricted the intake by 1/3 and opened up the exhaust some more. Last fall I had 1/2 of a successful flight with the cowl on. That is to say the first half of the flight I had a nice smoke trail and proper engine response. Then about 5 minutes into the fight I noticed the smoke trail I had was gone and throttle response from 1/2 to full was poor. It must have leaned out and/or got hot so I landed. After a refuel and some more adjusting on the ground the next three take off attempts resulted in the engine suddenly quiting at around 50% power and as the airplane picked up speed. I slowly advance power on this airplane to maintain control. Finally, we held the airplane upright at WOT and it suddenly quit again. I now have the engine and fuel tank out of the airplane. The fuel tank looks fine and was properly connected to the engine although I have found it will flood the engine when the tank is full. I am waiting for warmer weather to run the engine on a test stand again but found it needed a valve adjustment. Measured valve clearance was .2mm and I set it to .04mm.

I'm using YS 20/20 fuel, MA simitar 12x8 prop and taching around 9,800 rpm. Peak is over 10,000 rpm.

Any advise would be welcome. Hopefully I provided enough information.

w8ye

My Feedback: (16)

Reaffirm that your tank height relative to the needle valve position is correct

Quikturn

My Feedback: (12)

This is what I came up with . I outlined the fuel tank and taped it on the fuselage to show how it's mounted. The center of the fuel tank looks pretty close to the needle valve I think. I'm not sure how I could move it if I have to.

The pictures show the fuselage inverted. Do you see the short piece of fuel tubing from the tank to the carb.? It loops "down" and then "up" to the carb. fuel nipple. Would it be wise to use a longer piece and make it go "up" out of the fuel tank instead?

I also included a picture of the cowl so you can see the cutouts.

NM2K

My Feedback: (14)

I remember when Saito came out with that plastic backplate and a lot of us complained about them, before Saito admitted that they had goofed and changed them to metal. I even remember some folks bragging about how much lighter they were and how it was a performance improvement.

Sorry guys. Plastic is never an improvement.


Ed Cregger

GaGeeBees

My Feedback: (23)

Looks like you need better air flow for cooling. The rule of thumb I've always used for cowled engines is the exit of hot air needs to be 3x the size of your fresh air intake. Both intake and exit look too small. The fact that it runs fine with the cowl off would seem to confirm this.

charlie1960

have to agree with GGB on this.