OK, I've mounted this beauty on the test stand and I'm getting ready for it's maiden tank.

It will turning a 14x8 4-stroke prop, I'll use 18% nitro w/20% castro, and keep her under 4K RPM's for 2 tanks.

Now what? Tune? Better Mix? Adjust? Etc...

Newbie to 4-strokes and don't want to mess it up.

Thanks!

I just about have one of these broken in now (about two gallons of fuel). I was also new to Saito and 4-strokes and breaking it in was quite an adventure. I am glad to hear that you have yours mounted on a board. If I had it to do over again I would have done it this way on a board, instead of on the plane:

Saito says to start it up the first time with the main mixture adjustment 4-5 turns out and the low speed mixture screw flush with the surface. This is an extremely rich condition- it will run rough, go through fuel very fast and make quite an oily mess. Make sure that the motor is very well primed, especially at first. If the motor gets lean it will backfire quite violently. I destroyed two props and an aluminum spinner due to backfires until I recognized this trait. If you plan on using an electric starter then use a plastic spinner until you have the motor adjusted and stable. And use a locking nut and make it very tight!

After you run the first tank or two I would begin adjusting the high end and use a tach to get the RPMs up to at least 8500 RPM. This should correspond to the mixture screw being around 2 to 2 1/2 turns out. Then I would go back to the low end mixture and start turning it in until there is no noticable drop in speed at idle when the glow plug is removed. You will probably have to turn the screw in around 2 turns to reach this point. Don't be in a rush and let the motor go through a few more tanks of fuel as you adjust it.

After about a gallon of fuel you should be able to lean the motor to a "normal" condition, which should be around 1 1/2 to 1 3/4 turns out. Then go back to the low speed screw and try turning it in further to get a smoother idle and reduce fuel consumption to a sane level. If you get too lean then the motor will want to backfire or quit when you advance the throttle. You should end up with the low speed turned in 2-3 turns from its starting point.

The motor really loosens up with time and RPMs will increase for a given setting as it breaks in. After two gallons I am flying it at around 9400 RPM peak with a 15-6 prop. And it goes through a 16 oz tank of fuel in a little under 20 minutes.

Good luck!

Here's a good site for you: saito-engines.info/

DON'T mess with low speed needle for initial break-in. They come from the factory pretty much right on. For the first few tanks of fuel run the high speed at about 5 turns out for a saito 91 or larger, as for 91 or less keep it at the 2.5 turns out. Also keep in mind not to exceed the 4000rpm mark while on the first few tanks of fuel. These are not 2-strokes, and require not only a little more cash to buy, but a little more tlc.

I believe that the Saito manual says that you may have to leave the glow starter attached during the initial run-in. This is because the initial factory settings are so rich that the motor may not keep running without it! With the factory settings, the motor that I just broke in would drain a 12 oz tank of fuel in about 6 minutes of idling, even after leaning out the high-end. The factory low-speed mixture is good for initial break in, but not for flying.

I agree that you can't be in a rush. This motor is not an OS 46FX and it really needs the break-in time. And it needs to be kept very rich during the break-in process. But my experience is that the low speed mixture must be leaned to "reasonable" before the motor can be flown, and this would be best done while still on the stand. I began adjusting the low-speed mixture during the 5th tank of fuel, which is about 1/2 gallon, and slowly worked my way to the current setting over the next gallon. This is what I tried to describe in my previous post.

So, Shubox (and others)- how much fuel would you run through the motor before starting to adjust the low-speed mixture?

When you adjust the low speed needle, remember that it is not air bleed (unless it's a 30) so you turn it clockwise to lean unlike an airbleed carb. Saitos costs a lot of money but well worth it.