rcFp

I have just finished breaking in a new saito 72 engine.
i tried to break in the engine as the manual says while keeping the engine under 4k rpm for at least 15 m.
i used the following setup
1) fuel - morgan 15% 4 stroke fuel
2) master airscrew 13/6

there are several things which i not sure about and i would be very happy for your help :

1) i got min rpm of 2600 under that the engine is rocking and making hammer like noise . is this rpm is good enough and why the engine is so rocking and making the banging noise.

2) i tried after an hour of running the engine to reach max rpm .max rpm was 9300 is this good enough and should i keep it reacher for the next few hours

3) during this first hour of breaking in the engine i got something like 7 backfires. why so much and is there something for me to do ?

4) the engine should be installed on morris fun fly . this is my first four stroke and and seems to me that is has quite a lot of power and vibration. is this setup is valid/safe ... ?

5) after just an hour the muffler was fully covered with dried oil stains (new muffler version) is it supposed to happened ?

sorry for all this Q but this is my first four stroke

thanks

FlyingPilgrim

My Feedback: (26)

Your .72 will only idle smoothly after it has been broken in a little more. Hammering at low speed sounds like you are trying to get it to idle at a lower rpm than it is capable of running (until it's further broken in). If you're getting backfires, richen up your mixture. It doesn't sound like it's totally broken in yet. Keep it rich until you get some more run time on it. Varnish on your muffler is normal. If it bugs you, take some steel wool to it to clean it up.

PigMan Buggerus

My Feedback: (6)

If you want to avoid the stains on your muffler, try going with a totally synthetic oil fuel. I use WildCat ys 20/20 blend in my Saito 100 and I haven't seen any problems with the muffler getting stained..

I would also recommend that you don't use a fuel that has less than 20% oil content. It's what saito recommends, so I imagine it's important.

JB Rekit

My Feedback: (3)

The reason why it is knocking so much at the low rpm is b/c your low end setting is too rich. When you let it idle for 30 sec to a min and floor it does it blow out tons of white smoke? If so you need to close the bottom end needle a little. Just 1/8 turn at a time (clockwise). If you go too far with it then when you floor it, it will just die. Then just open it back up 1/8 of a turn.

And the bottom end effects the top end so as you are leaning the bottom end you will probably need to keep checking the top end b/c that will probably need to be richened.

ilikeplanes

I had a lot of trouble with my 72. It wouldn't idle, the mid range was too rich, and I couldn't seem to find the "right" prop. Everyone told me I just need to wait for it to break-in. I waited and waited, and finally, after over a full gallon of fuel, it started to behave. I use 10% CoolPower with no problems. Almost everybody at my club uses 10 or 15% CollPower in their Saitos. At least 50 engines and countless years all running well.

I wont go into tuning, there are as many opinions as engines on this subject. I will say though, you need to give the engine time and be willing try different needle settings. If you lose your baseline, refer to the manual. You'll get it eventually.

On the other hand, my Saito 120 started first flip, was tuned and running perfectly in ten minutes. I was so confident in this engine that I flew my brand new Ultimate (three months on the building board) on the second tank of fuel. I flew three times that day and never had a single problem with that engine. The Saito 120 is a dream.

rcFp

It seems from your answers that the knockings are common at this stage
so what i would like to know is :
1) can i install the engine on the plane and continue the breaking in process on the air
2) is it safe to install it at this stage on morris fun fly
3) 9300 rpm seems a bit low what do you think

FlyingPilgrim

My Feedback: (26)

By all means, install it and run it. Just keep it rich until you have it broken in. Use a tach and make sure you are at least 300 rpm below peak. Don't worry, it will eventually reach a higher peak, just don't rush it or you may cause damage from running lean. Read the manual and adjust the needles according to the directions. As it wears in, your idle will get better. Enjoy it, they are wonderful engines.

Pilgrim

SpaceCase

My Feedback: (4)

So from the idle (Low) screw being flush with the throttle arm hosing, whats a good refrence point for a 72 saito being optimal? I'v been trying to adjust it with some difficulty. You really should go in in 1/8th increments? Iv read you might be looking at one to two full turns in, is that right?

PigMan Buggerus

My Feedback: (6)

SpaceCase,
Mine went in at least a turn, I am not for sure how much. What I did to set my low end,(I would only recommend doing this if you are running the engine on a bench, or in some other fashion where there is no danger to getting your fingers in the prop) was to bring the engine throttle down to as low of an idle that it would reliably rermain running, then lean the low end. if the RPMs pick up, lower the throttle again. Continue doing this 'til you can no longer lower the throttle without the engine dieing. If it isn't safe for you to try to adjust it this way, start with a little larger than an 1/8 of a turnat a time, say a quarter turn, then start making smaller increments as you approach optimum. As always be careful of your fingers, don't do what I did, it was painful, and took about 2 and 1/2 months to recover from, broken bones and all.