Don41

Have a backfiring four stroke? I have several smaller Saito engines and none of them ever gave me a backfire problem but my new 125 (about two hours on it) is a prop spitting champ unless I start it thus

Fill tank, leave glow off and fuel line disconnected. Spin engine for one or two seconds with electric starter, hook up the fuel and heat the glow. She starts immediately and purrs like a kitten. Forget to follow this procedure though and you'd better duck because the prop is coming off (:-).

I checked the valves and even used lower nitro fuel but nothing works other than exhausting the cylinder prior to glow heat.

The start procedure is not a problem with this particular plane (Four Star 120) because the engine is upright and the fuel line exposed. I'm hoping that the beast will settle down during the next few hours because next season I'll be mounting it in my soon to be started Spacewalker. It will be under cowling and upside down. Tremble (:-)

Regards

John 38

I find my larger Saitos backfire with a vengence if I have the throttle too far open.

my start procedure is to get the engine wet by hand propping it with finger blocking silencer to blow fuel over - best done with the throttle open.

then cut throttle back to idle position, hand flick in proper direction to ensure not too wet , connect glow plug and chicken stick the prop backwards against compression -, and as long as engine was wet it fires immediately in correct direction

Jezmo

My Saito 180 is just like John's decription of his larger ones and quite different than my 91 Saito. If I open the throttle (on the 180) just a tad too much she'll kick back hard. It also likes to start rich or "wet" and that helps with the kickback. Good luck with yours.

jimcork1

My Feedback: (4)

Has anyone had an issue with saito backfire in the air. I have a 1.8 that has never backfired in the air. Yesterday while flying I pulled the throttle from wide open to full idle and turned final to land and the engine backfired once and quit. It actually did this on 2 flights but only when going from full throttle to idle quickly. Engine top end is 9500 on cool power 15% with OS F. Engine starts and runs well with normal power and exceptional good idle. But the backfire is not fun to have the prop stop. Thanks vettdvr

daveopam

My Feedback: (9)

My 1.80 has back fired in the air a few times. Like yours, it's when I went from full throttle to idle fairly quickly. One more click to the rich side will stop it most of the time.

David

jimcork1

My Feedback: (4)

low or high needle

daveopam

My Feedback: (9)

High is what I adjusted. One click stopped it.

jimcork1

My Feedback: (4)

I"ll give it a try. I normally drop 250 rpm off of top for the high needle.. Perhaps I left it a bit tight.

Did you ever have a plug do this?

daveopam

My Feedback: (9)

I never thought about a plug doing it. I have 5 other smaller Saitos that never do it. I just thought it was a little lean on the high end and was building heat in the engine. Either way the engine did keep running.

David

yojoelay

My Saito 125 kicks back badly on first start up if it is just a touch too wet. On the first start up I plug the exhaust with my finger and turn it over to bring the fuel up. Once the fuel reaches the carb I give it one more turn then hit it with glow and the electric starter. If it is too wet the backfire will kick the prop loose every time. The answer for me is not to over prime before the first run and to just start it on subsequent runs.

This motor is mounted inverted, runs on 10% fuel that I mix myself (12% synthetic and 4% castor) and has never backfired in the air. It has about 2 hours running time all up and is running a new plug (the original was replaced after run-in).

Hope this helps.

Joel

jimcork1

My Feedback: (4)

Just an FYI ,, my Saito .56 mounted inverted. I never choke it for starting. I just set the throttle just above idle and crank with electric starter. Never backfires.

AA5BY

Yep... the Saito 1.25 is tight and sensitive to too much wetness on startup. In fact, my starter won't get it over so two differing techniques are used. I normally hand prop it carefully holding the prop firmly in the full hand until it bumps.... then flipping the prop using only my finger tips against the front prop surface and even so occasionally it will numb them. The other is to use the starter and power the on board glow after the engine is spinning over. Both of these of course require starting at idle throttle setting.

Greg Wright

My Feedback: (6)

Don, it sounds as if you need to adjust the low end. When i had my saito 1.25 i originally broke it in like they said in the manual. Then i started to fly it and adjust the needles after i had a gallon of fuel through it. I no that saito's are known for there low end needles to be set pretty rich from the factory so it will just take a little bit of adjusting. I don't remember how many turns in it took until i had a good reliable idle and throttle response but just keep adjusting it. I personally never had a backfire with mine and i flew the plane pretty much every week end before i sold the motor.