w8ye

My Feedback: (16)

Most of the commonly available K&S tubing at the LHS is brass but they do sell Aluminum and copper in some sizes.

Hobbsy

My Feedback: (102)

Hey Ron, my Giant Sportster is in my avitar, Jim if I remember correctly WR suggested 2.5 times the venturi diamter for the VS length. I hacked about 3/8ths inch off the one you see. You could easily go for 3 times the venturi diamter on the 1.25 because it doesn't see 10,000 rpm.

RPMcK

My Feedback: (1)

w8ye or Hobbsy, Sorry for being a pest - just one more question. What is the difference if any between belling (flaring) the end of the VS and cutting it on a slope? Is there any particular prefered orientation to the slope when it's installed on the engine.

Well OK, two questions! Thanks for all the information. Have a great day.

Ron

BTW Hobbsy - I REALLY like your Giant Sportster too!

beaver180

My Feedback: (10)

Geez your lucky Ron, my wife won't let me play with anything fullstop! []so I build my planes

My 180 is now running alot longer on my 32oz tank than the ten minutes it did before ( many Thanks Hobbys and w8ye ) After peaking the HS needle I started leaning the LS needle from a point where the screw was 1/16th in from flush ( with the plastic throttle horn on carby ). Make sure your prop is on really tight for if the motor backfires, mine didn't.
Other than that just do exactly as described... works a treat. I certainly didn't know the LS setting would have had such a huge bearing on the way ours Saito's run. Plus now there's not too much spitting out of fuel from the carb.

CFN, Paul

Hobbsy

My Feedback: (102)

Ron about all I pay attention to is that the opening isn't aimed at the engine mount and that the fuel lines don't cross it. All WR said about the flair and the baloney cut was that the baloney cut approximates the flair by getting air herded in the right direction a little more gently than cut of square.

RPMcK

My Feedback: (1)

Yeah Paul, I probably should have phrased that about my wife a little differently. But what the heck, maybe she meant no fun at home too. Glad to hear your 180 is running well now. I've only had mine a short while and I am really pleased with it so far. I seems to run better with every tank of fuel. What prop are you running on yours? I've been running a 16X8 on the bench stand but I think that may not be the best prop for it. It turns it up pretty good. I kinda feel like when it unloads in the air it could over speed the engine at full throttle. I haven't had a chance to try any other prop yet. Thanks again Hobbsy for answering my repeated questions about VS's and all the rest. There is no doubt I'll be back with more questions for the group. thanks again.

Ron

beaver180

My Feedback: (10)

Hiya Ron,

I've got a Master Airscrew Classic 18x6 on my inverted 180. It's turning that in the high 8's. I have a 32oz fuel tank mounted back on the CG ( this is in a 15.5lb 105.5" Citabria ) and have a Cline pressure reg to deliver the go-go juice.

Now that it's running better and using way less fuel with the tuning of the carb I think I may be slightly under prop'd. At full throttle level flight can hear the prop whine.

CFN, Paul

sodbuster 1

Got the 1.00 tuned right.
There was no problem with the tank or the engine or any of the other components.
OR THE MUFFLER

It was technician error. [X(]


A.) I didn't realise I would get such a boost of RPM from the addition of the muffler
(Even though it says so right in Jims advertising)
B.) (more importantly)I had switched from a 14 x 8 to a 14 x 6 and forgot that it would jump RPM SIGNIFICANTLY

I had adjusted the HS needle till I THOGUHT I heard it sag and backed the RPM down to where it had been running on the 14 x 8! Which of course put the engine in a way over rich setting.

Once I got the HS set right today Which by the way was 10,350 running 300 rpm rich.I still had to adjust the LS needle a bit leaner(two and a half turns from flush) to get the right idle (2200) and good transition .

One thing for sure, the change of the muffler definitely makes for needing leaner settings both high and low. Especially on the low.
Which in my mind can only be good as it's going to make for better fuel economy and longer flights.
And by the way, a big Kudo's to Jim of RC Specialties. A fine product and fine service.

If my earlier post was in any way taken as anyones thinking I was saying anything negative about the muffler from Rc Specialties,please don't,and my apologies if it was.
I was simply asking what I was doing wrong.
I knew it was my lack of experience with 4 strokes and having to tune an engine with a tach

Rudolph Hart

Everything sounds pretty normal sodbuster,fun learning is'nt it

I've made heaps of mistakes so far and don't mind,the engine sounds so good you know?

sodbuster 1

Does have a nice sound.....
kind of like when I put Cherry Bombs on my '69 Stang oh so many years ago lol.
The only difference is that this muffler actually helps gas mileage!

healingover

My Feedback: (3)

Great thread!
My son and I are new to the RC Plane Hobby and enjoying it very much. After flying a NexStar trainer we just bought an ARF, CAP 232, and a new Saito 72 GK.
We have had problems starting it until I read this tread back in its infancy. William Robison stated that they needed to be flooded at prime and then a 1/4 trottle and then good to go.
Question, there is a black adjusting screw on the side of the carberator body that the manual doesn't cover. I have played with it and adjusted the 72 so it runs good but what does it actually do? Where should it be set?
I have jumped to the newest thread and noticed Bill has not posted any thing in a while. Enjoyed reading his posts!
I wondered if you are still excepting Members, if so My son and I would like to be encluded.

Thanks for your help

Steve and Dylan

Hobbsy

My Feedback: (102)

Steve, WR passed away a while back, the black screw is most like the idle speed adjustment, if you have a digital radio just back that screw out until you can completely close the carb barrel. It is also the barrel guide so do not remove it completely, leave it adjusted to just where the barrel is closed to stop the engine when you want.

RPMcK

My Feedback: (1)

Hi Paul, From what you're telling me the MAS 16X8 that I am running right now is not a big enough prop for the 180. Mine is already turning the 16X8 at 9700 on the bench leaned out to peck and I don't have full gallon of fuel run through it yet. I've got a Zinger wood 17X8, a Xoar wood 18X6 and a MAS Classic 18X8. That's the extent of my inventory. Hope to get a chance to compare them in the next few days. Let us know if you change props what you come up with.

I'm putting my 180 in the 80" Giant Super Sportster if I ever get it assembled. Don't recall the size tank it came with but I'm using the Cline regulator also. Love those regulators. Just recieved another one yeaterday that's going into my next project. Keep the faith, Catch ya' later.

Ron

w8ye

My Feedback: (16)

The 17X8 and 18 X 6 are the correct props

RPMcK

My Feedback: (1)

Thanks for the information w8ye. I sorta' figured the 18X8 might be a little much. What do you think about a three blade. Would a 16X8 three blade be about right then? Don't know if I'll need the clearance but it would look cool!

Ron

Paul_BB

Hello all,

I am fitting my new Saito 72 on a new airplane and I am thinking about placing it upside down. [sm=72_72.gif]
Am I wrong ? Is there something against this configuration ?

Thanks for sharing your experience.

Paul

michaelyager

Gentleman,
How are you doing? I have been out of the R/C world for the last 10 years and have just recently returned. I am currently in Afganistan and have a TREX that I am flying (and crashing). I am scheduled to ratate at years end and I have been planning and purchasing items for an Airplane-the Great Planes U-Can-Do .61. I have been flying this on realflight and love it, not to mention some of my local club members have this and love it also. I have planned a few changes while building this plane though. First, I will mount the fuel tank at the CG. I will power this bird with a Saito 125 and I would like to route the exhaust down under the exhaust tunnel. Does anyone know what manifold, exhaust pipe and muffler I will need for this? I do plan on putting a Cline regulator on this engine since I will be moving the fuel tank. With the exhaust moved back, should I tap the manifold to provide the needed pressure?

Thanks

AJsToyz

I actually like them upside down or side mount for ease of hand starting. Otherwise they will run however you mount them.

Andy

Paul_BB

Thanks Andy,

It won't get flooded too easily ?

Paul

AJsToyz

That really depends on where your tank is mounted , if the tanks to high , the engine can flood. After filling the plane I turn my plane and radio on and set it for about half throttle. Then I'll plug the exhaust with my finger and give it three flips. I'll set it back to just above idle , 1/4 throttle at the most , hook the glow plug up and it usually starts in one or two flips.

Andy

healingover

My Feedback: (3)

Hobbsy,

Thanks for the help. We will back the idol speed screw on the 73gk out a bit then use the radio to set everything.

Thanks again

Steve

NM2K

My Feedback: (14)

-


Not to be argumentative (who me?), but my ST G2300 handles the 18x8 with ease and its a 1.40 two-stroke, as everyone knows.

I'll have to mount up my Saito 1.80 and run comparisons between the 18x8 and other prop sizes that have been mentioned here. Of course, it depends upon the airplane that one is flying too, as to whether a propeller is suitable or not.


Ed Cregger

RPMcK

My Feedback: (1)

Right you are Ed about the prop needs to match the airplane. Be sure and follow through with your investigation and let the rest of us know what you learn. Thanks! Oh BTW aren't two strokers suppoose to produce more power the four strokers anyway? Oh yeah, but four strokers produce more torque, or so they say. Oh well, whatever. Your experment should be interesting.

Ron

cpsdd56

Hello all I asked for some advise a couple of days ago on a Great planes stuka with FA100 and got nothing. Am I not giving enough info? or not asking the right way . Any help would be greatly appreciated. Thanks

beaver180

My Feedback: (10)

Pretty sure the general rule of thumb when going 3 blade is to drop an inch in daimeter... so if your running a 14x8 you'd go 13x8 three blade.

When the prop is spinning you can't see whether or not it's got 2 or 3 blades, maybe ( and just a suggestion ) get a suitable looking 3 blader just for static looks and use the 2 blade for flying??

Someone else, with 3 blade experience will chip in now I'm sure

Cheers, Paul