RPMcK

My Feedback: (1)

Shubova
Hobbsy and bawls and others have already given yuou most of the answers about the FA 115 and the velocity stack (or lack of one) that fits. One of the LHB I talked to last week was not aware of the 115 either. Guess it's fairly new. As for what I have found concerning the velocity stack. The one you posted the link to will bolt on but the bore is too small for the 100 and up size carb. I'm not sure about the 92. That is what Horizon Tech Support was telling me is why they don't recommend it for that engine. I wish there was one that actually fit and if anyone finds one please let me know. Right now it looks like the 100 thru 125 are orphens. Has anyone by the way done an actual bench test with and without the stack? How about it Hobbsy?

Regards, Ron

sodbuster 1

Installed an RC Specialties Turbo muffler on my 1.00 this weekend and am having trouble getting the engine tuned right again.

Seems like no matter where I set it it has a hesitation transitioning from low to high which it didn't have with the stock muffler and manifold/pipe.

Had to lean the low end almost 2 turns to get a somewhat reliable idle and I believe I ended up having to richen the top end 3-4 clicks to get it run halfway decently.
Am I doing something wrong here?
High peaked at 9,600( richened to 9,200) running an APC14 x 8 and 2,200on the low end

retransit

My Feedback: (18)

I doubt the muffler pushed it out of tune. I bolted on an RC Specialties muffler on a Saito 1.20 and a 1.25, replacing the originals. I had no issues with either one except that it sounded better than stock and picked up some RPM. Maybe you should be checking fuel, fuel filter, glow plug, valve clearances, etc. The muffler works just fine on my engines.

Bob

w8ye

My Feedback: (16)

I've run the Turbo mufflers on a half dozen different Saitos and there were never any tuning problems

beaver180

My Feedback: (10)

Hey Soddy ( and anyone else )...

What type of prop are your using? Could it be you are using too light a prop? As far as I understand four strokes require a heavier type prop to give "flywheel" weight and effect, where by the engine can idle, at lower revs and spool up smoothly.

I know this to be pretty much right as a guy I know was trying to use a light weight wooden. It wasn't until he changed to a heavier nylon/glass filled ( MAS Classic ) of the same diameter and pitch that he got lower and reliable idle speeds and the engine performed, ran-up much better. Another guy said he could have used a heavy prop nut of washer instead to get the same effect.

Is this right guys?? Could this be something that new to 4 Stroke owner don't realise??

I'm always learning

Cheers, Paul

RPMcK

My Feedback: (1)

beaver180. Sodbusters problem probably doesn't have anything to do with the prop since his engine seemed to be running to his satisfaction before and he doesn't indicate he changed anything but the muffler. That said I agree with w8ye. I have one of RC Specialties mufflers and am happy with it. It most likely is a fuel delivery problem or a tuning problem. But then I'm sure someone smarter them me will have the answer. And maybe it is the prop (?). But he says he's running an APC prop. Are they as heavy as the MAS props?

Ron

beaver180

My Feedback: (10)

Yeah I probably could have worded myself somewhat better... I do know that Master Airscrews ( especially the Classic's ) are heavier than the APC's

Maybe the more knowledgable can enlighten me about prop types to use with 4 strokes ( Saito's as I have two, 150s and 180 ) and their flywhell effects.

CFN, Paul

RPMcK

My Feedback: (1)

Paul - I'm sure not one to be second guessing anyone about four strokers since I've never had any experience with one until I bought my Saito 180. It's made a fan out of me and I'm about to add another one to my collection - as soon as I can make up my mind wheather to buy a 91 or a 115 to power a 60 size Fokker Tri-Plane project waiting in the wings. I will be really interested in knowing what you find to solve the problem with your 100 Sodbuster This forum has been a really valuable source of information to me - as I know it has to others. Ive learned a lot (and I thought I knew everything)[8D]

Ron

cpsdd56

Hi all i'm new here and need some help with a problem I cant seem to find a good answer to anyware else. I have a great planes stuka that weighs a little over 8lbs.Its powered with an FA100 my first 4S and i'm thrilled with it. Now to my problem,I cant stand the look fo two blade prop i'm using now. I'm not looking for a speed demon just good scale speed. On the bench it spun a 14x8 Zinger pro at 9600 with 15% fuel. I would be willing to give up some rpm to throw a larger 3 blade prop. It seems to me that the fa100 has more power than this plane needs. Any advise will be greatly appreciated. Thanks

indgroove

I am having trouble tuning my Saito 100 engine. Hand no trouble tuning the Saito 56.
Can anyone give me tips. I follow the instruction in the manual but when I was ready to adjust idle it was like I never made any adustments. How do you guys tune your Saitos?
Thanks,
Indgroove

RC Specialties

sodbuster 1,

I run the same prop on my 1.00. The usual change when installing the TurboHeader is a richer run on the high side which requires a readjustment. You did not mention whether the low side adjustment solved the hesitation. The 400 rpm below peak leaves it running a little rich and is a personal preference. I tune from 200-300 off peak myself, to conserve fuel and reduce the mess. Other problems as mentioned could be causing you problems. Let me know how it turns out.

Jim

Hobbsy

My Feedback: (102)

You should have leaned the LS needle after you put 20 minutes or so on the engine, the TurboHeader had nothing to do with the rich midrange. The two or three clicks richer on the HS needle is to feed the extra 200 to 300 rpm you're getting out of the engine now.

RC Specialties

Thanks Hobbsy, you explained it better. There still may be other issues if the engine is not stable.

Jim

Michaelh

My Feedback: (4)

The thing is, he said he leaned the LS to get a reliable idle. Not a reliable transition.
Id start the tuning over again on that one

crashnburnrc

My Feedback: (1)

Big-Mo. Sorry I didn't know I was treading on "your" thread. Just trying to get some questions answered. I'm fairly new to this hobby and need to get an engine in top running condition. I just wanted tips from everyone on any procedures that I may not think about. I can rebuild deisel truck engines, but have no idea where to start on this.
Thanks for watching my back Ol' Fart.

beaver180

My Feedback: (10)

Hiya Bawls.... just found this, may be of interest to all that haven't seen it...

VELOCITY STACKS http://www.macspro.com/velocity.asp

Rudolph Hart

Hi hobbsy it was a 13x6apc prop.I got all low rpms at peak,around 9 to 9/4 or 5 and it sounded like it was really grunting,but my God did it hiss and spray your fingers,it was kinda back firing at times and sounded like it wanted to chew my head off,repeatedly.I run that fuel in my hyper seven race engine at night,when you back off the throttle it backfires and barks at you with blue flame out the exhaust and they don't call it "we fu$k em" fuel for no good reason.Seen some old motorcycle single bangers run like that with jets you could read a newspaper thru.

Rudolph Hart

Welcome mate

Big-Mo

My Feedback: (5)

crashnburnrc: No dude i was just yanking yer chain , giving ya a hard time. It's an Open Thread about Saito's just go with it. I hope you get your engine running real good real fast ! .

Sorry if i sounded a little gruff. lol
Don

Hobbsy

My Feedback: (102)

Mike, that is why I settled on the procedure I now use the set the LS needle on fourstrokes.
First, make sure the LS needle is richer than it needs to be,
Second, peak the HS needle and leave it peaked,
Third, begin leaning the LS needle 1/8th turn at a time, checking the transition and top rpm after every other change.
Saitos will run very rich and idle very well when set rich so the transition has to be the governing factor in the final setting as you already stated. Since the LS needle controls the mixture for 80 to 90% of the rpm range it has a huge effect on fuel economy.
Important, keep reducing the throttle opening as the idle improves from improving the mixture. At some point one of the 1/8th turn changes will make a bigger difference than the previous one, you're getting close. It's possible by continued leaning to get a very slow idle rpm but be too lean, the transition will be hesitant, (or non existant) from being too lean and the HS needle will be ineffective. The needles are adjustable so you can adjust so don't be afraid, anything you do you can undo. Easy peazy.

Note how far in the LS needle is on my 1.25.

RPMcK

My Feedback: (1)

Hobbsy, Thanks for the picture of the LS needle on your 125 and your refresher on tuning procedure. The thing that really caught my eye is the "home made" velocity stack. After all my complaining about not being able to find one that actuall fit the 100 thru 125 It made me slap my head and say -"why didn't I think of that?" You just gotta' think out side the box. Thanks!!

Ron

Hobbsy

My Feedback: (102)

Ron, what I did was take one of the standard velocity stacks and remove the aluminum funnel, bore the hole out in the steel bracket, not easy, its hard stuff, then split a piece of K&S tubing and silver solder it in the bracket. If you wanted to go to the trouble you could probably get a piece of K&S the proper diameter, I chose slightly larger than the venturi diameter, and eliminate the splitting. William Robison and I worked out the approximate length and the 45 degree slash. The K&S tubing does not take kindly to being flared, it splits. The K&S tubing pretty much comes in 32nd of an inch increments I just split it and reduced the diamter of a larger piece because its what I have.

RPMcK

My Feedback: (1)

Thanks Hobbsy, From what you say I assume the angle of the "45 degree slope" is a factor as well as the length? I'll probably be trying this on a 115 when the time comes. Any suggestion as to how to determine the proper configuration? (length angle of slope and so on?) I'm no engineer but I assume there is a way to determine that. Actually building one is no problem - I'm fairly good at that - but figureing out the right configuration might be. But thanks for the information .

Ron

w8ye

My Feedback: (16)

The K&S tubing might be a lot more malleable, (workable without splitting) if it is heated up and quenched.

Use Hobbsy's picture to get a relative length. It is not that critical.

RPMcK

My Feedback: (1)

Thanks w8ye - I'll try heating it as you say. Is the K&B tubing brass or copper? I've used the heat and quench on copper spark plug gaskets but have never tried it on brass. After the descussion with Hobbsy I was thinking (now we're in trouble) that maybe one could take a velocity stack for one of the bigger engines (180?) and remove the bell and use it on the other base. Course making it out of tubing would no doubt be cheaper - the bigger stacks are relatively spendy. Maybe someday I'll look at it a little closer. Thanks again. Gotta' go work on my Giant Super Sportster. Wife says I can't play with anything else until she at least sees the Sportster taxi tested.

Ron