goose_wrench

I am new to 4 strokes and need some advice. I have the 82 with the plastic backing plate. I have had this engine for several years. I ran it on a stand when i first got it to break it in and had to put the hobby on hold for several years. My son is now old enough to get into the hobby with me and we have built a Senior Kadet together. We brought out the engine and put it on the stand to start to tune it. It runs great at idle, it will do 2400 - 2500 all day. It transitions great but it surges at wot and only reaches 8800-9000 with a wood 13x6. I feel like I am chasing my tail. I lean the needle and the rpm will start to rise and it will either sag or quit at 9000 rpm. If I start to richen it will load up and drop rpm quickly with only a few clicks of the needle. I have fresh fuel and a new saito plug installed. I have now disassembled and cleaned the carb. I am ordering a reseal kit before trying again. I noticed the o ring in the intake pipe on the head end was a little deformed. Am I heading in the right direction or am I overlooking something simple? I love the sound but this thing has been a little bit of a pain. It also vibrates pretty good at wot. Is this something that will clear up over time or another issue? Thanks in advance.

1QwkSport2.5r

I'm gonna guess it's not broke in yet. Unless you ran a gallon through it, it's probably still not run-in enough to not sag at a normal flight mixture. How much run time did you put on it when you ran it last total?

goose_wrench

I've ran about a total of 3/4 of a gallon. I know it will take a little while to break in . The biggest reason I was concerned was that every where else that I have read shows higher rpm readings. I just want to make sure everything is working properly before I install the engine.

1QwkSport2.5r

If it will fly the plane with a rich mixture, then you're good to go. The engine will get better and better the more time you put on it. Readjust your needles each outing and use a tach and you'll see the difference over time. Be sure to check and readjust your valve lash periodically. Usually after a bench break-in l, I'd be checking the lash and adjusting it back to the tighter side of spec.

Rudolph Hart

Goose they do sound good eh? do you have a prop balancer and a tacho.The wood props are very light and a heavier mas classic 14x6 will do the job.You should get a consistent and reliable 1800 idle easy.The o ring at the top of the intake tube needs watching it's to lean at full throttle.

1QwkSport2.5r

If an .82 is too lean turning a 13x6 at 9k, she's a weak sister. Something is wrong with that picture. I agree, surging indicates a lean mixture.. Just need to find out why it's so weak/lean.

goose_wrench

The o ring in the back of the head had lost a lot of its elasticity and looked square from a cross section view. I hope that is the problem. I am being very cautious because I have learned the hard way over the years. If it is not right on the ground it's not going to get any better in the air. Thank you guys for the responses. I think I will pick up a 14x6 mas classic and see "how low can you go" . My son and I love the way it sounds at idle. Thanks again guys.

jeffie8696

Surging can also mean a bad plug.

Rudolph Hart

Yes i had'nt thought of that.Goose check the intake tube at the top and make sure the steel washer is still there it supports the back of the top o ring on the intake.It slides off and is easy lost.

goose_wrench

I am going to order a seal kit from my hobby shop tomorrow. They are not open Mondays or Tuesdays. I'll also pick up a new plug. I had all ready changed it but new doesn't always mean good. I will post as soon as I get it back together and running. Thanks again for the support.

blw

My Feedback: (3)

Did you tune the low speed needle valve until you got it about 1/8 of a turn too rich? This is same as setting it 1/8 richer when it won't surge in the air anymore. I would keep the low speed a tiny bit rich for the first 1 to 1 1/2 gallons. On the low speed needle of a Saito, just right can be defined by either 1/8 to 1/16 of a turn on the screw.

Rudolph Hart

Barry is right if you are flying at half throttle most times and full throttle should be 3 clicks rich off peak generally.

IQ if you have a well tuned saito and the tank position is good you get little variation over ten minutes flying in a thin smoke trail and max performance at a safe rich setting.It's so easy to go leaner with castor.

Goose i'm no mechanic and don't really understand carbies at all,it's a bit like learning algebra at school.I have a tach for peak rpm.The lsn i set by sound and what happens.

Hobbsy

My Feedback: (102)

Saitos run so well when set too rich it's hard to sort it out by the sound and visible things. The lack of fuel economy and the shaking are very tell tale. The hesitation on acceleration can be caused by either too rich or too lean. Barry's suggestion to go too lean on the LS needle, then back it out an 1/8th turn is about good a way to do it as any. This is all made easier with the HS needle at absolute peak since the HS needle seat is fixed and does not move, therefore the LS needle adjustments do not alter it. Having the LS needle too lean will render the HS needle ineffective.

1QwkSport2.5r

What I was getting at and perhaps I wasn't real clear, but (without any firsthand experience on a Saito specifically) I would think an .82 4-stroke should turn a 13x6 (wood no less) at a good bit better than 9,000rpm. If it was surging or sagging at that rpm on that prop, either its a weak engine or it's just not broke in. An air leak is a real possibility, but I'd still think the rpm should be higher. My Enya .60 4-stroke turns an APC 13x6 at 9,990rpm on 5% fuel. The Saito .82 should spank the Enya by at least 500rpm I would think. Maybe I'm off-base being I don't run Saitos.

Before tearing into the engine too much, I'd be certain the fuel tank and related plumbing be absolutely leak free. If the clunk is a filtering type, ensure it can flow enough fuel. I used a felt clunk on a ST .90 and found it ran lean even with the needle held in by 1 thread. With a known good fuel tank, I'd verify the valve lash is set correctly, use fresh fuel, and a fresh glow plug if the coil of the plug is any color other than shiny silver. If I suspect an air leak, I use a fuel bulb with fuel in it and dribble fuel around the leak probe areas. Any fluctuation in rpm will indicate the leak if one exists.

I go overboard sometimes... Sorry.

blw

My Feedback: (3)

Dave, I may need to clarify my recommendation. You are absolutely right about peaking the HS first, and then tuning the LS but my reply was meant to be a short suggestion. Peaking the HS, etc was implied. I know I wrote to set the needle 1/8 rich, but that was the short version to see if the advice would be taken.

Signs of a poor LS needle setting are surging, gasping/wheezing, poor fuel economy, low power, smoke trails like OS's, and a poor idle.

One other major part of tuning the low speed is the need to fly the plane around the field and listen to it once you think you have the LS where it should be. I have to land about 50% of the time and richen up a LS needle a tiny bit when I tune one after I hear how it sounds flying around. It only takes a couple of minutes.

Tim, we are mentioning all of this on you because Saitos are different that most other engines. Plus, we use the standard algebraic system over here for the carbs, and the metric crowd (such as Old Fart) doesn't understand the math behind it all. y o u h a v e t o s p e a k s l o w l y to h i m

1QwkSport2.5r

I understand, Barry. If sub-9,000rpm on a 13x6 wood prop is normal for an .82 engine, I totally get it. They're really different.

Hobbsy

My Feedback: (102)

Barry, I wasn't correcting, I just sort of started at the beginning, the ,82 I had was nearly as strong as most .91's.

Rudolph Hart

Barry let's just say if you stood out in your front yard facing australia and shouted at me (lets just say i could hear it from this far away) my comprehension would be slower than the speed of sound time frame we are talking here.I suppose a good math guy would calc the distance to here and divide that by the speed of sound? to get a time...

Goose do you plan on changing the tiny o ring inside the main needle sleeve ? it helps to make up a tiny wire jag for those..and a big beer fridge good luck.

blw

My Feedback: (3)

Dave, I know you weren't but I worded it where it did come out sounding like that is how I tune the LS.

Tim, I never said it was normal and I said that tuning the LS is different on Saitos. I think a wood 13x6 is way too light for the 82. The APC 14x4W is a popular prop for it. The engine should be turning some high numbers. 3/4 of a gallon is broken in enough for confident flying and turning at least high 9's. I haven't run mine that much yet, so somebody may post that it should be turning even more than that.

Old Fart, are we talking about a straight line to Australia, or using Great Circle distance to figure it out? Math is not for me either. I've never been able to retain it.

wcmorrison

My Feedback: (2)

Be advised the O-ring on a Saito used in the head is Viton. The O-ring used in the carb area is not, Be sure you put the Viton O-ring in the head. I have seen Saito users take a "tie wrap" and strap down the intake manifold to the cylinder head. That ensure the intake manifold is up tight against the head. It may only require you do to that to fix the problem. Surgiing can indicate an uneven supply of fuel getting into the engine. Make sure your exhaust pressure nipple is clear, that the fuel line is not cracked, etc. Thus make sure you have positive pressure on the fuel tank at all times. I have had four stroke engines run well on the ground but surge in the air only to find that the pressure line has been compromised some kind of way.

Rudolph Hart

WC is an acronym here for a toilet system just kidding friend.I think it's ok to just use any old hardware o ring kit it does'nt get that hot on the intake side even after you shut the engine down,that's been my experience.A lot of chat was happening about plastic backplates so go figure (means have a bloody good think about it in australian) i have two 82's with lots of flying time,plastic backplates and so far no problems,they support the intake tube well.Dave if you can remember the 91 figures on a 14x6 it would be interesting to compare them to the 82 you used to have.Like you mine are very close within 500 odd rpm and the newer 82 is lighter and powers 46 size deccys well.

Barry maybe someone here will figure it out.I'd cheat since i'm development friendly and bore a whole right thru the middle.

blw

My Feedback: (3)

The 72 is the engine with the plastic backplate problems. I wouldn't worry about the 82.

WC is right about the piton o ring, but I've used the hardware store ones without problems like Old Fart suggests. I don't even look for piton ones anymore.

I recently ran both the 82 and 91. I didn't write anything down, but I recall the 91 sure seemed to be more engine with more torque power. Both are fine engines but I would put money on the 91 turning a bit larger prop *in the air*.

goose_wrench

The seal kit is on its way. Hopefully so is the solution to my problem.

wcmorrison, I will go through the fuel system with a fine tooth comb. Thanks for the advice.

oldfart, I did get the o ring out of the spray bar. I used a small seal pick and a small fridge of beer

blw, I am going to pick up a 14x4 when I start running again. I think that might make it a little easier to land with the senior kadet.

wcmorrison

My Feedback: (2)

WC, yeah, I get it. Spent a little more than six years on the continent and visited Merry Ole England a few times. Stands for William Christian. That is a mouthful to say and too much to write down. But it is the names of my two grandfathers. So I go by Chip. And like all good folks when in need do use the WC.

BTW it is Viton not piton. Viton takes the heat but I am sure the other O-rings will work. Yes, there has been a lot of talk about the plastic back plates, a weight and cost reduction effort. Many said the plastic allowed the crankcase to distort, causing problems. My old .91 has a metal back plate and I do not have such problems. Even more so, as now days I fly using a Maggie .91 (or if you like ASP). My Saito .91 sits in an old model that needs repair. I should get around to doing that someday.

Meanwhile, keep on flying!

Cheers.

blw

My Feedback: (3)

OF- maybe we should call him Lou???