Ok, picked up a saito 91 4-stroke today....its going in my 4*60 that im building...

My first time with a new engine (my other plane is a nexstar, comes already broken in)

So i made up a nice stand to break it in on....very stable, nice setup...

Due to a wrong recommendation from the guy at my LHS, the spinner doesnt fit on (the cone, the backplate fits and holds well, just the cone doesnt fit over the 12-8 prop)

Since i didnt have the cone on, i used a chicken stick...

After a while of adjusting the height of the gas tank (too low, not holding its prime, too high it drips out of the carb...fun) i got it straight, got it to hold its prime, now im happy, checked glow plug and ignitor, good....ok, 3...2...1....spin....POP.....and prop comes loose....

Ok, maybe flooded, did that once with my nexstar (with the electric starter, just spun the prop off) ... took off glow plug, spun it up a few times, even inverted it to make sure...

Put everything back together....spin it a few times, spins good....no binding out of the usual, spins through a few revolutions without tough binding....

Put glow ignitor back on, spin with the chiken stick...it tried to start but was backwards...got a little combustion, but only made just a little bit of a turn....spin it again...loud POP

again, prop loose....put prop back on tight...check for flooding, nothing....

Im not going to try it with the chicken stick again....going back to LHS tommorrow and getting a good spinner...and will try it with the electric starter...

Anyone have an idea what the pop was....im not sure if it was the prop spinning back and hitting my chicken stick....or if it was something bad...

Im kinda nervous about hurting this engine in any way....not cheap....but i cant see what im doing do any damage on a motor thats supposed to last a while...im not (As far as i see) doing anything rough or out of the ordinary....

Hope i get some replies, will be a coupld of days before i try again, my dad is headed out of town for a couple of days, and i dont want to start it up alone....just incase something bad happens....

thanks
Joshua

I did this with my .46 AX , after trying and trying til i was blue in the face ! The next day i went and got the proper cone and used my electric starter and it fired up within 5 seconds .

rjm1982,
Ok, you're more than likely not going to hurt the motor, so relax. Backfiring a 4-stroke will definitely throw a prop, but you know that by now, just feel lucky that you didn't do it in the air and loose a prop and spinner. I'll try to answer all your questions, but if I miss one please let me know.

For break-in you can take the spinner and backplate off. Tighten down the prop nut as tight as you can get it. Throw away your little 4-way wrench and get a box end wrench and a glove. With the 4-way you'll never get it tight enough. Use a box end wrench to tighten it, oh yeah, the glove is for the hand holding the prop so it doesn't cut your fingers. Don't worry, you're not going to be able to tighten it enough to damage and threads, but that's why you should use a box end so you don't slip and round off you nut.

After you get the prop tight, prime the motor but don't get too much fuel in it. Too much fuel (or being too rich) is the main reason for a backfire. To prime the motor, open the throttle to full (make sure you DO NOT HAVE YOUR GLOW STARTER ON), cover the end of the muffler, rotate the prop until you see fuel pulling into the carb, and then turn the prop through another compression cycle. Then take you finger off the muffler and rotate the prop through a few cycles to pull the fuel into the motor. Then connect your glow igniter and try again.

A trick you can use for starting a motor without a spinner is to pull the rubber insert out of your electric starter and turn it around. It will have a small hole in it that you can fit over the prop nut and rest the silicon up against the prop. Before you do that turn your motor over in a clockwise direction to just before it hits compression, then put the starter on it and try to start the motor.

Hope this helps.

Hi Joshua,

The Saito is a great motor. Please follow the instructions with regard to running in R I C H to the letter. I will bet the noise you heard was a backfire and the nut coming loose.

The spinner can be modified to suit your prop. Dremel to the ready.

Once the motor is primed, with the glow plug igniter removed wind the motor backwards until you feel the compression. Now power up the plug and flip the motor backwards. It will fire and start forward. When the motor is run in you will find the back fires go away and unless you change fuel, plug or prop size will not need any tuning. Dont forget to set the tappets after run in.

Out of the box you will probably find the low speed adjust is super rich. Not an issue for run in but my last two new Saitos required considerable adjustment once run in for smooth transition.

Cheers,

Colin

Chicken sticks are nice , but you can sit their all weekend fooling with it or get a starter. Even the best of engines can be a pain to start and if I had to rely on a chicken stick, I may as well use my finger cuz thats the only way I'll see any "action."

I just broke-in my Saito .91 and it was very easy for me to start despite it being my first 4-stroke and inverted. I followed the directions given by Saito and cranked it for a few seconds with an elec. starter and I didn't even realize it was running until I pulled the starter off.

As for the prop coming loose, if you don't have the "safety nut" on, put it on. This is the second nut that "jams" into the primary nut. When you use a spinner, the spinner adapter acts as the "safety nut".

I strongly suggest using an electric starter.

Make sure you are running the engine RICH during breakin.

After the engine is broken in, if the engine is not "putting out smoke", it is too lean. You need to have the engine "smoking".

Yeah, the lock-nut was on...just kicked loose on the backfire....

Im getting a spinner today so ill be able to use the elec. starter....

And i have it set to what they say (leave low-speed alone, high speed 2 1/2 turns out...)

thanks guys....

As a side note....after i tried last night....now there is a little clicking in the valves, i can tell if its the exhause or intake....it wasnt there when i first turned it over straight out of the box....is it normal for it to pick up a little noise...(not loud, and the valves work fine)

Clicking is a sign of a valve out of adjustment. My OS manuals say to adjust the valves after the first hour of running. I do it after the engine comes off the test stand, 2 tanks of fuel for break in. I then check them again after an hour, and then another hour after that. I'll give you a hint for keeping track of when to do you maintenance. I use a flight logging program to keep track of all my RC equipment. Get Flight Log from Shawn Lammers, www.lammers.ca. Set up and log all of your time with each engine. After every flight session log the flights and then print out an overdue maintenance report and it will tell you if it's time to check your valves, or any other maintenance you've set up.

On a side note, this program is a good reality check of how much time you spent flying, I'm talking about actual time in the air and not time spent at the field. So far for 2005 I have just a hair over 6 hours in the air!!!

Hope this helps.

Couple more questions....

Did i read right that to start a 4-stroke with a chiken stick, you spin in backwards?

And as far as trimming the spinner, its off by a good 1/8 inch....dont you have to worry about gettting the balance right?

I know, i worry too much....just so much money....

And as far as a flight log...yeah, im looking into that...

And here is a pic of my homebrew break-in stand....it fits over and screws down onto a saw-horse...works pretty good (well, feels pretty good, we'll see what happens when i spin her up...)

Yes, you heard right. By flipping the motor backwards. What happens the the motor hits the compression and flips back, causing the motor to turn counter-clockwise and start.

Your test stand will work, but you need to anchor it down. The motor is going to pull very hard and you don't want it coming loose when you are anywhere near it.

1/8" is not too much to trim off of a spinner. Just make sure you trim the same amount from both sides so that it stays in balance (more or less).

So much money? Wait until you hit 5 figures. It doesn't take long.

Hope this helps

wow....thought those were supposed to thumbnail....oops...sorry...

Yeah, it gets anchored...i screw it to a sawhorse....which for some reason or other, had large dowels on the legs, and we will put a little weight on the back ones just to be safe....if this thing could move a sawhorse, i would be very impressed....

Hi Josh, just my two cents. Breaking in a 4 stroke with a chicken stick can be done, but it's MUCH easier with an electric starter. I figured it out after my first engine, I didn't think it was possible for a 4 stroke to run backwards but they will if they're rich enough.

Some break in suggestions, not mine but from an old guy out at Fentress who's Saitos always seem to run just a little bit better than everybody elses. In other words, he knows what he's talking about!

Rich, rich rich. First couple tanks of gas thru the engine shoudl be so rich you can't run it without the glow starter. Hard on the starter, but good for the motor. Then you can start leaning it out. You do have a tach, right? He (Willie) considers minimum break in 1 gallon of fuel thru the engine on the bench, NOT SYNTHETIC! Don't run castor oil in a Saito, but for break in you want something a little less "slippery" than synthetic. Helps the engine's moving parts seat in better. Dont't exceed 4k rpm for the first 1/2 gallon or so, just keep it ticking along. Personally, I don't consider a Saito really broken in untill it has at least two gallons thru it, then I'll start leaning it out and really looking for peak performance. Adjust the valves after your first gallon of fuel, before you mount the engine on the airplane. If you need help I'll be out at Fentress this weekend.

Andy

Yeah, im definatly running it through rich for break it...and im gonna trim this spinner so i can use it to use the electric starter....

And no, no tach right now...i know that jose has one, so once i get it broken in (not going to stay at full throttle too long during break in...and im not really gonna lean it out much till i get it on the plane and at the feild where you guys know what is going on....plus im pushing it on money as it is...ive pretty much spend my tax return and it hasnt even came in yet....

Cya this weekend...and oh yeah.... BUDDY CABLE BUDDY CABLE BUDDY CABLE ... just kiddin, i know i shouldnt be relying on other people...but damn, every time i go to debbies i spend at least 100 bux...i gotta stop that...

If your only spending $100 when you go to the LHS then I'm going to take you with me on my next trip to the LHS. Maybe you can keep my spending down to ONLY $100!!!

It works...its alive even....hahahaha

Sorry, im happy....i got it running today, just trimed the spinner a bit....got it on, and within a second of putting the starter on it, it was going strong....

Started it 3 times...each time was the same....only ran for about 2 minutes total.....was in my garage (raining) and just wanted to try it...damn this thing smokes alot more than my 46fx (then again, the 46 isnt set so rich....)
maybe its just me, but i like the smell of the glow fuel.....


Anywho...thanks for the replies...

btw, i checked the valve clearences, they seem to be good...but im still getting a clicking noise...it sounds like its comming from the botom of the pushrods?

I'm assuming this is with the engine not running? Normal. A word of caution about your engine stand though. I would get rid of that chip board and use a good piece of hardwood. As oil soaks into that chip board it will soften and could break loose around the engine bolts. I've broken in a couple of Saitos on a bench mount attached to a saw horse and while there's no chance of it getting airborne, my Saito 1.00 would slowly drag the horse along the pavement at full throttle after a gallon of fuel and the needles were tweaked!

yeah, the particleboard is going to go bye-bye....i did give it a few coats of toungue-oil just for a little extra (it soaked it up good, and now the fuel just beads up on it....)

but im going to make a new one with a better mounting system (so i can custom fit to different engines) and make it all out of hardwood sealed with laquer or somehting....


I know what your talking about though, it was dragging my sawhorse around even at just above a smooth idle....

He (Willie) considers minimum break in 1 gallon of fuel thru the engine on the bench, NOT SYNTHETIC! Don't run castor oil in a Saito, but for break in you want something a little less "slippery" than synthetic. Helps the engine's moving parts seat in better. Dont't exceed 4k rpm for the first 1/2 gallon or so, just keep it ticking along. Personally, I don't consider a Saito really broken in untill it has at least two gallons thru it, then I'll start leaning it out and really looking for peak performance. Adjust the valves after your first gallon of fuel, before you mount the engine on the airplane. If you need help I'll be out at Fentress this weekend.


Now I am confused. If it's not synthetic oil and it's not castor oil, then what is it? I am new at r/c and I have only heared of those two types of oils.

Castor only during break in. Sorry, I tend to ramble on a bit at times.

Andy