w8ye

My Feedback: (16)

Here are a couple live actions pictures, one of a four stroke and one of a two stroke. Then there are two cut aways of Saitos. These pictures came from RCU

spec36

it dont get any easyer than that good job

spec36

william im just about to reach the first two hours on my 72 can you tell me a page # were this has been talked about thanks

William Robison

My Feedback: (3)

Spec:

I f you mean a post or information relating directly to the total time on the engine, there is none that I remember. If on the other hand you are asking about problems particular to the FA-72 like the flexing of the back plate and eating the intake seal, those comments are spread throughout and there's no one place to go.

The FA-72 originally had a really flexible back plate, allowing the carb to vibrate, hammering the o-ring at the cylinder end of the intake pipe. The material was changed to make it stiffer and a slight amount was added to stop the problem. In most cases it has worked, but I had one come in for three weeks in a row with the problem. Even with the new back plate. Finally cured it by adding two turns of safety wire around the cylinder and the pipe to holds it rigid. No more trouble.

Bill.

spec36

i was talking about valves im sorry did not finish the?

William Robison

My Feedback: (3)

Spec:

Set the valves both at 0.0015" clearance. Do the adjustment with the piston at TDC between compression and power strokes.

Covered in the manuals and Saito Notes. I can send you the Notes in .txt format, and the manual in .pdf. I may have sent you copies, but I don'r remember having done so.

Send me your email address, either by PM or email, (don't post it in open forum) I'll get them out to you.

Bill.

loughbd

I know exactly what the ports are in a four cycle engine and what they are in a two cycle. There isn't anything you can do in a small model airplane engine that will give you any kind of power gain that modifying the ports in a two cycle will. You can't make them big enough to do much good and they are so small that polishing won't do much either. Messing with them is inconsequenctial compared to working with the valve train.

blw

My Feedback: (3)

Flew the .72 again today without any problems. I changed to a 13x6. Needle valves still stable without adjusting, so I'm thinking that epoxy in the backplate bolt holes worked. Thought I would pass this on. Mine has the new backplate and I added washers under the bolt heads. The first signs of problems were always with the engine running lean. Richening sometimes helped for a minute or two, but then required more richening. Then, the engine wouldn't tune at all. It was always a lot of chasing the setting with adjustments up to half a turn.

I've thought about the idea of tapping holes in the bolt heads to safety wire the bolts together. I can't remember if that is positive or negative safety wiring, but it would work to keep the backplate bolts secure.

loughbd

A leaking back plate should no effect on a normally aspirated four cycle engine. Their crankcase is vented to the atmosphere. For all practical purposes the backplate just keeps the conrod from coming off the crankpin

Tom Jones

My Feedback: (4)

Hey WR don't know if your the guy to ask about this but ow come the page numbers don't show up the front page of the engine forum? It's kinda inconvenient. Thanks Tom

WALKERS210-RCU

My Feedback: (36)

For what its worth I have a FA120 that I put on a homedesiged profile. The orignal engine on this was a RCS 1.40 Gasser and it was a dog compared to the Saito 1.20. Only problem I have ever had was last week I had to flip the prop two times to get it started. It was the glow driver not the engine.

William Robison

My Feedback: (3)

TJ:

Good to hear from you again, it's been a while.

The deletion of the page numbers from the thread list just happened, I don't know why unless it was to get more room for ads. Once you're in the thread you have the selection of the ten pages around your location with a single click, or you can click the down arrow in the box to the right of the page numbers and select any page in the thread from the drop-down list.
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WALKERS210-RCU:

Welcome, glad you accepted the invitation to come in. You are also a milestone, you are number 250 in Club Saito.

Bill.

Hobbsy

My Feedback: (102)

A leaking backplate does indeed effect the performance of a naturally aspirated four stroke. When the engine crankcase is breathing through the vent hole there is a small positive average pressure in the crankcase, if there is a leak in the backplate a larger volume of air taken in through the leak than can enter through the vent hole, now the crankcase is an airpump moving air in and out ot the leak instead of just out through the vent hole. Pumping the larger volume of air in and out of a leak is hard work, reduced power is the result. No backplate at all would be better than a leaky one. Of couse that invites dirt.

old-pilot

Bill;
On a post you made on 9-19-05 on the Glow Engine thread you said in order to reverse rotation on the 56, use SAI 30 T34 cam "shaft".

Please verify that it should be SAI 130 T34 cam gear. (The left cam on the 100T)...Thanks a bunch..

William Robison

My Feedback: (3)

loughbd:

When the back plate screws get loose it's not the air leak at the back plate joint that gives a problem, it's purely the loose back plate. The carb in the mid block Saito engines mounts to it, loose screws allow more movement of the carb, this aggravates the tendency to eat the upper seal of the intake pipe.

Bill.

BQuartucy

Bill R.
Saito 100, mounted inverted, glow plug heater. Adjusted for good idle, and WOT. Mid range is iffy will sometime backfire and run in reverse. If the engine is adjusted so the midrange is smooth, WOT is to lean. How do you adjust for all three to be smooth. The tank is
mounted a bit to high,(GP Ryan STA) probably ok for a OS engine. Tried a perry oscillating pump no help. So please.... HELP......

loughbd

The crankcase of a two cycle is an airpump. It has to be to get fuel?air into the engine and then into the cylinder. A four cucle does not intake fuel through the crankcase. It goes dirstly into the cylinder through the intake valve.

I just took a Saito 45, loosened the back plate so there was an 1/16 of an inch slop in it an ran it. It ran fine and except for the fact that the case wiggled and didn't hold the carb solidly mounted had NO effect on the way the engine ran. I also took a broken back plate (lower right srew hole broken out) leaving about a 1/4 inch hole in the case and ran the engine with that. It didn't give a hoot and ran just fine.

Non RC related content removed.

loughbd

That's true but it doesn't affect the way the engines runs. eventually it will damage the intake o ring but that's it.

loughbd

I just did the experiment again with a 65. Took an extra backplate and drilled progressively bigger and bigger holes in it starting with the breather hole. When that was as big as it could get, I started drilling 1/16 holes in it. After 10 holes I quit. Total of 10 1/16 inch holes and one big 1/4 inch hole. This has ZERO EFFECT on the engine performance. About 9800 rpm on a zinger 13x6. I also ran it with the back plate screws backed out 1/16 inch. Same results. No effect on performance.

Ernie Misner

Question: will ordinary exhaust deflectors melt on 4-stroke mufflers? The LHS told me absolutely not to use them on 4-strokes, but at the field I do see them....?

Thanks,

Ernie

William Robison

My Feedback: (3)

loughbd:

Quote:

...it's not the air leak at the back plate joint that gives a problem...

You have taken three posts to say what I said in one sentence fragment.

Bill.

Hobbsy

My Feedback: (102)

Ernie, I could never get them to stay on but never melted one, I did melt a piece of Tygon tubing today running my 1.25, I was using an IronBay regulator and had the check valve in a piece of Tygon, during the first run it simply melted into nothingness and blew away as the tubing fell away.

William Robison

My Feedback: (3)

BQuartucy:

You need to open the HS needle a bit more. The HS needle only affects full throttle, as you close the throttle by the time you get to 1/2 throttle the LS needle is controlling the mixture.
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Ernie Misner:

You can put the exhust deflector on a four stroke, you wont hurt anythung except the deflector. Depending on how you fly it will last indefinitely, or it may fail on the first flight. The exhaust temperature can got well above what the deflector will withstand, but if you're a "Gentle" flier it may not.

If you want one, give it a try.

Bill.

William Robison

My Feedback: (3)

All:

Let's have a moment of prayer for Art Grabow and his family, he died last night. Known to all on RCU as GrnBrt, he is already missed.

Bill.

PS: If you object to a moment of prayer, then just give us all a moment of silence.

Bill.

whaturi

question. my saito 100 idles wonderfully (2000 rpm) with the low needle jsut 1\8 turn open. is this bad? i was messing with it today, and i let it idle like that for about 5 minutes straight. so i know it does not die like that.. just seems strange that it's sweet spot is so close to closed.