It is important to differentiate what YOU require, as opposed to what the ENGINE requires. If YOU require a certain nitro require, that’s fine. But don’t confuse that with what the ENGINE requires. I have actually seen, and read about Saito’s running FAI fuel. That’s, right-0% nitro. Saw that at Sepulveda RC field in Los Angeles. In addition, I have also read about Saito’s running FAI fuel a number of times.
At the opposite end of the spectrum, I have read numerous times, about RC guys running Saito’s like a “poor mans” YS. They drop the oil content, and really jack up the nitro. 30% nitro in a Saito is not uncommon in RC. Saito’s will haul the mail if you do that but; the first thing to go in them is the bearings; next you will take out the head.
A lot of confusion about 4 strokes stems from their relationships in RC. The YS and the Saito were every specifically designed, to serve the needs of different sectors of the RC community. YS are, and have always have been, targeted toward the dedicated RC competitor. Even their early-pumped 2 stroke motors were targeted there.
The extraordinary success of Saito motors is due to their highly focused direction at the RC sport flyer. Most RC flyers are not competitors; they are “Sunday flyers”. The Saito is the RC communities LA46. They are without question, the least fussy, and most user friendly 4 stroke ever developed.
It is a testament to how flexible and user friendly they are in that, they will run absolutely fine on a fuel designed SPECIFICALLY for the needs of a competition motor i.e., YS. They will also run fine, on a range of fuels that the YS simply will not.
The ONE thing the Saito’s don’t seem to tolerate is different glow plugs. They really only seem to run well on one plug, and that is the F plug. This is virtually universal throughout the RC community. In my case, I simply could not get a steady idle on my 72 without the F plug, (yes, I set idle). The other issue is, my big block had an annoying “surge” in flight without that plug.
This has caused Saito no end of embarrassment, and consequently, they contracted with a major plug manufacturer to duplicate and make the F plug. When you purchase a new Saito, the plug that it comes with, is basically an F plug “knock-off”. But rumors die hard in the RC community, and guys will still automatically chuck the OEM plug, and pop in an F plug. The OEM plug, very closely duplicates the run characteristics of an F plug, but very simply, will not last as long.
By the way, I have used an F plug in an ST46 and ST51, and it ran beautifully.