AJsToyz

Ken,

I kinda went Saito crazy !! Replaced most of my engines with 4 strokes , and all Saito's. Dave should be able to help you out with out a doubt. Between a few of the guys here there is a huge knowledge base. Was it the 72 that the back plate can warp and let the carb leak ??

Andy

Ken Cz

AJsToyz,
Thanks for the help.
Since I know very little about Saito it may be one of the problem models. I just don't know.
Dave is going to help me out and that is fantastic!

Ken

AJsToyz

Ken,

Dave will be able to help you with out a doubt ! I have a 72 on my Yak , great running engine , hope you get it going soon !! I'm in Michigan too and going into fall your flying time will most likely be limited.

Andy

w8ye

My Feedback: (16)

The Saito 72 is the one with the back plate problems.

The 72 and the 82 share the same back plate but the intake tube on the 72 is not made as well as the one on the 82 and even on the newer engines with the redesigned back plate, the 72 will show up with more intake tube leakage problems.

stallwart

How wierd. I experienced almost identical problems with my 72 today. I have flown with it many times in the past, installed it in a new plane and have had it running reliably for re-tune in the new plane, taxi tests, etc. Today, it wouldn't cooperate.

The engine is mounted inverted, as in the past. No tank or fuel issues that I could discern. It's a relatively new purchase of an engine ordered by the dealer in 2005 or so. Would it be a candidate for the backplate issue?

Hobbsy, do you make house calls?................lol

w8ye

My Feedback: (16)

Upon visual examination from the outside, distortion of the back plate can be detected and the the condition of the intake tube gasket into the head can be visually seen.

The intake tube can be grasped with the fingers and moved in and out of the cylinder in extreme cases.

Also in advanced cases the aluminum backing washer that serves to hold the seal in place becomes worn and slides back down the intake tube onto the carburetor.

If you're around a lot of 72's you will sooner or later see one where the owner has fastened bailing wire around the cylinder and intake to hold the intake tighter against the cylinder.

One problem with the back plate is that it softens and the screws become loose. After removal you will see the ears are distorted on an old back plate.

Installation of a new back plate is usually followed by using washers under the retaining screws. The washer on the top left screw will need to be filled down to clear the back plate.

Ken Cz

W8YE,
I have the exact conditon you mention - the carb manifold/intake tube can be grasped with 2 fingers and easily moved fore and aft. Even when full seated to start it moves rearward to expose the O ring with only limited run time.

Can this be what may be causing the kind of run problems I mentioned a few posts back?

What is the fix? A new improved backplate? Do I need a new intake tube?

Thanks!
Ken Cz

w8ye

My Feedback: (16)

You have a classic example.

The typical fix is to install an new back plate and intake O rings and use washers under the screws that hold the back plate to the engine.

With new O rings and the little aluminum washer most people get by without having to replace the intake tube.

Saito charges an arm and a leg for the intake tube for some reason?

w8ye

My Feedback: (16)

http://www.horizonhobby.com/Products...rodID=SAI8091B
http://www.horizonhobby.com/Products...ProdID=SAI7269
http://www.horizonhobby.com/Products...rodID=SAI7217A

Some Saito 72's came from the factory with washers under the back plate screws. The factory washers are small and are hard to detect with the screws still on the engine.

mike early

$23.39 for the 125, and I've had to replace it twice. It's crazy.

wessco

My Feedback: (7)

is there an o-ring in the "head", where you push in the intake tube? Is all that's there is that metal washer thing?

wessco

My Feedback: (7)

Found my answer....that's where the Viton o-ring goes. it ran fine without it....

Rudolph Hart

Nah sod

If i lose the floor jack i'll have to sit behind the engine while it was running..the handbrake would get suicidal.

The 82 has had five tanks thru it now and have done it the way hobbsy said.Sure has a nice bark to it.

Cheers mate

beaver180

My Feedback: (10)

With many thanks to you and hobbsy ( and OF for makin me laugh! ) my Saito 180 is purring now and getting stronger each time I light the fire

This is my lastest pix from the weekend at Wigram Airfield ( ex RNZAF base ) in Christchurch where I fly....

Hobbsy

My Feedback: (102)

Mike, I'm curious as to what happens to those intake pipes, I can't imagine anything short of a crash damaging them and even that doesn't look possible.

sodbuster 1

yeah, but mount wheels to the legs and you could be the hit of the neighborhood!

w8ye

My Feedback: (16)

In a crash, something dense like a battery will make a dimple on the back side of the intake pipe

mike early

Two sessions of lawn dart activity. The plane accordions behind it and smashes the intake tube. The firewall-box is plywood and either fiberglassed over or epoxied to fuel proof it.

blw

My Feedback: (3)

I don't know if anyone has mentioned this yet, but you can also use some RTV to seal that o ring better on the head. My .72 gave me problems after using the new backplate, washers under the screws, and RTV on the seal at the head. The screws were backing out after a couple of minutes of run time.

Saito uses some sort of thread locking compound here anyway, so it is a good idea to lock those screws back. I used epoxy in the threads and it hasn't backed out since then.

mike early

When selecting a prop, what RPM at WOT (on the bench) do you shoot for, in general?

w8ye

My Feedback: (16)

You don't want to exceed 11,000 consistently in the air

You would like to run at least 9000 on the ground

Beyond that there are a lot of variables as to speed or thrust

blw

My Feedback: (3)

I've read about guys using the Eagletree systems and prop unloading in the air is very unpredictable with every engine/prop/airframe combination.

mike early

Thanks. I was wondering just how much they unwound in the air.... Pretty hard to determine that, I imagine....

RC Specialties

Mike,

I have always propped my Saito's at low to mid 9k rpm on the ground. There are allot of variables, but I have been told that you can expect about a 1k unload increase in the air. Some may disagree. However, I have never had one to over rev with that starting point. The best way is to prop for your flying style and keep a good load on the engine without over doing it. Staying within the suggested prop ranges will keep you safe.

Jim

Rudolph Hart

Nice picture of the port hills in the background paul,and apart from a nice looking aeroplane or two,includes the old mess hall in the background i think and there should be a couple of huge arched concrete hangers to the right of that?..might be thinking of ohakea.

Fired the 82 up for it's sixth tank full the other night and can't understand how old age can be boring.Near on set the shed on fire.Had my foot hooked behind the saw stool leg with the throttle wide open and the tach behind the prop.Leant forward(no glasses)to read the prop number with my handrolled cigarette clamped between my lips.The prop wash blew the glowing end off,and back into my tee-shirt,burnt my stomach and i jumped.Saw horse took off and i can't decide whether to chase it or try and put the carpet fire behind me out,workshop got saved and i need a new prop.

Hobbsy when i throttle the 82 back to four grand and listen to the cam and followers from close to on the left rear side..sounds just like a jewellers time piece,yummy.