Canardman

My Feedback: (7)

I just finished a P-51 with a Saito 100 4/stroke. Seems to idle ok and dies out at full throttle. Someone said an ign. pack may cure that. I have set the "high" speed jet in and out. seems to make no difference. I would be grateful for any help.[&o]

Campy

My Feedback: (1)

On board ignition is to prevent the engine from dying AT IDLE.

It sounds like a fuel problem. Larger engines "tend to get thirsty", especially at high rpms. You will need to check the following items:

1. Is the fuel line the correct size ? I am not certain if the Saito 100 uses medium or large fuel line. If it uses large fuel line, make sure you also change the line INSIDE the tank going to the clunk AND the brass tube that goes through the plug.

2. Observe the fuel lines CLOSELY while the engine is running, especially when moving the throttle to full. Are the lines collapsing ? If they are, you will need a fuel line with a thicker wall.

3. If you have an inline fuel filter, remove it.

4. Is the pressure line from the muffler/crankcase firmly attached to the tank AND the engine ? Are there any pinholes in the pressure line ?

5. Are you using the "stock" glo plug or an aftermarket ? If you are using an aftermarket plug OR the stock plug has been used for awhile, try an OS "F" type plug.

Hope this helps.

apalsson

My Feedback: (1)

Or is it possible that the fuel tank is touching a hard surface in the airframe so vibrations at full throttle cause the fuel to foam?

MinnFlyer

My Feedback: (4)

Does it quit when it's been running wide open, or does it quit when you go from Idle to Wide open?

staggerwing

My Feedback: (5)

Are you sure that it's not running too lean. You should drop the high needle setting back 300-400 rpm from max. Remember that it leans out more when flying.

Stick Jammer

Is this Saito brand new? If it is, it needs to be broken in. You want the needles set very rich for the first couple of tanks to the point of raw fuel coming out of the exhaust. You'll most likely need to leave the glow igniter attached for the first two tanks (on the ground of course). As mentioned, on-board glow is typically set up to come on at low throttle. MinnFlyer has a good question, maybe a little more info would help to get you the best answer.

Canardman

My Feedback: (7)

I do have a fuel filter on it, I'll run it w/out it this weekend. It dies out when you reach about 3/4 throttle, and just quits when you open it all the way. The tank is wrapped in foam. I have opened the high speed valve about 8 turns out with no effect. The fuel filter seems to make sense. I thank you all for the advise. I have several things to try this w/e. [sm=thumbup.gif]

jaka

Hi!
It sounds as if you have dirt in the carb fuel intake. Clean it out and see what happens.
No an onboard glow ignitor (at idle) is not necessary!

Regards!
Jan K
Sweden

piper_chuck

My Feedback: (12)

Curious about this recommendation. Many people say always use a filter. Others have said never use a filter. Can you elaborate on why you say to use one?

bbbair

Let's not forget the basics, has the Propeller been balanced?

If not it could cause vibration that will make the fuel foam, engine over heat, tuning will be impossible and so on.

Is the propeller snug on the shaft or is it wobbling? A shim may be required.

Always check the basics, they are the first things to be over looked and the easiest to correct.

rc-sport

My Feedback: (12)

It too rich, 8 turns is an awful lot for the Saito. I have 2 Saito 100's and the high end is open about 2.5 turn, 3 tops. CLose your top end needle all the way and open it 2.5 turns then give it time to warm up then try it. Also how old is the glow plug? Is it the original you used to break in the engine, if so replace it with an OS F plug.

Campy

My Feedback: (1)

I did not say to use one. I said if there is one, REMOVE IT. An inline fuel filter often restricts the fuel flow, and if it is not changed on a regular basis and becomes dirty IT WILL restrict the fuel flow. Engines need an unrestricted fuel supply and large engines use A LOT more fuel than a smaller engine. In addition, it is also another thing you need to check if/when a problem occurs. I have been flying for several years now and do not use an inline fuel filter. I have had no problems at all.

As you initially stated, there are different opinions on this, as well as which brand of radio is the best, Armorall in the fuel to stop foaming, ect.

Richard L.

My Feedback: (24)

If an inline fuel filter got dirty, then it did its job of keeping metal shavings and other crud from entering the engine, which could have scored the cylinder wall/piston and clogged up the fuel passages. An inline fuel filter is much cheaper than an engine overhaul.

jaka

Hi!
Get rid of the on-board filter!!!!
Never ever take eventual problems up in the air...they belong on the ground.
Always use a good big auto paper filter in your fuel supply..never ever use those small hobby filters on board a plane or helicopter....they always clog sooner or later.....!!
Regards!
Jan K
Sweden

Richard L.

My Feedback: (24)

Like I said above, a clogged fuel filter is cheaper than an engine overhaul.

What prevents the crud coming out of the exhaust from re-entering the tank through the muffler pressure line?

Sullivan Crap Trap is a big, high flow fuel filter that's transparent so one can easily tell if it's starting to clog.

Don't use at least two fuel filters on YS engines and you will be sorry.

Stick Jammer

Canardman,
You still have not told us if this engine is brand new or if it has been broken in already. 8 turns out on the high speed needle is typically WAY too much fuel for a Saito 1.00.

rc-sport

My Feedback: (12)

Don't worry about the fuel filter, your way to rich.

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Your idle needle may be set to lean.