This is the second and final report on the Saito 40A break-in. The motor has nothing short of tremendous torque. In fact, I would go as far as to say that the 40A appears to be more powerful for its size than my 72.
This particular 40A came well set-up by the factory and passed all my initial checks without any adjustments or modifications - nice touch. My 40A needs a somewhat tighter valve spec than my 72. The head configuration on the 2 motors is different. That is fine with me, as I will set them anywhere I can get the motor to go through the pattern reliably.
Right now, the motor will just barely hold a reliable 2500 rpm idle and that is because the fuel does not have enough nitro in it to keep the plug lit below these figures, (the fuel is for my high compression 72). I haven’t taken it up much beyond 8,000 rpm and don’t really plan to at this point in time, as it is still new. In addition, I don’t think it is necessary to run the motor much above those rpm’s because that is not where it makes it power.
The fuel economy of this motor is nothing short of unbelievable. Where as, you pretty much need a full gallon to break in a Saito 72, the 40A can probably get by on half a gallon before careful first flights. My 40A just loves the oily, high lubricity custom fuel that I use, and a slightly higher nitro version of this fuel is what I will be using. As for props, anything under 11” diameter appears to be a waste of time and power.
It is my opinion that the breather nipple in the 40A position, (front side high) does a better job of lubricating the “front end” of the motor than the breather nipple position of the 72, (front middle low). To no surprise, the 40A appears to be breaking in faster than the 72, no doubt due to smaller all around bearing surfaces.
I found absolutely no discernible operating difference between the new Saito 4 stroke plug and the venerable OS Max F plug. That said, one of the main differences between the OF Max and other 4 stroke plugs is LIFE SPAN!! All things being equal, you are still far better off with the OS plug because it is less likely to crap out on you in the middle of an overhead eight. The OS Max plug in my Saito 72 has been operating reliably for the last 5 years! Among RC flyers, they don’t debate this, if its 4 strokes of any brand except YS, its OS Max on the plugs, period.
The one thing that has been definitive for me has been the use of the “old school” 1.5 volt hobby battery as opposed to the modern 1.2 volt nicad drivers on the 4 stroke plugs. It has been my experience that four stroke motors need a hot, bright light to get the party started and the 1.5 volt battery simply delivers.
If I was going to “pick planes” for the small block, right off the bat, I would look at ships with thicker than normal airfoils. Ideal ships for this motor would be a Skylark, a profile Cardinal, maybe even a scaled down Patternmaster; or planes where the venerable Supertigre 46 would normally get the call. I would avoid ships like some of the Old time legal planes, like the Barnstormer, Tucker Special, Jamison Special etc. It’s my feeling that this is just too much motor for this class of plane.
The big question, would I put a 40A in a Nobler? You bet!! A well built Nobler, say a good kit or scratch built version; forget the ARF, would absolutely be deadly. Granted, you are going to have to hang it out at the end of some relatively long lines, but, if I wanted a combo for serious local Classic and Expert work, this would have to rank right at the top.
In summation: If you are serious about obtaining first time 4 stroke experience, I can’t see any better route then the Saito 40A. While the motor is no longer officially imported into the Unites States, you can still readily obtain them direct from Kaz Minato. Money well spent.
Milton G. Graham
Topic: Proparc Saito 40A Break-in Pictures (Read 1351 times)