ive got a p51 with a inverted saito 100 ..i was told it needed a onboard warmer for glow plug. (it dies when warmer is takin off) i know it should shut off after half throttle or so, or it will burn out the plug. does someone make something like this? i have a trainer plane that i fly, but the mustang is my 1st built plane, and would like to get it running. i also read on a post about 4stroke fuel is crap and to use heli 15-30%.is that right? also it has a custom exaust, that doesnt use the breather off the crankcase. it seems to suck fuel fine..is that ok? any insight would help

Originally Posted by supachronic2001

ive got a p51 with a inverted saito 100 ..i was told it needed a onboard warmer for glow plug. (it dies when warmer is takin off) i know it should shut off after half throttle or so, or it will burn out the plug. does someone make something like this? i have a trainer plane that i fly, but the mustang is my 1st built plane, and would like to get it running. i also read on a post about 4stroke fuel is crap and to use heli 15-30%.is that right? also it has a custom exaust, that doesnt use the breather off the crankcase. it seems to suck fuel fine..is that ok? any insight would help

I have a Showtime 90 size with a Saito 125 in it mounted inverted no onboard glow with no problems. I noticed with both my Saitos after i started them with glow driver on and then removed the glow driver then it would stall the fuel mixture is to rich i would lean the mixture a little then it would run fine. The fuel i use is either Omega or Cool Power 15% with no problems at all. The breather off the crankcase does not hook up to the muffler anyway just point the line towards the ground thats it!!! The muffler fitting goes to the fuel tank to pressurize tank to feed the engine fuel. Hope this helps.

I have never had any problems with mine being inverted. You should be fine.
nick

if you have not already, lean the Low end a couple turns in, they come set very rich for break in. you will know the low end is lean enough when at idle you can pinch the fuel line and it will almost die (drop in rpm's) immediately. also you should be able to run at idle for a long time and punch it with instant response (if it dies, it’s too lean, if you get a big plume of fuel and oil it’s rich)
use a OS F plug they are $$ but last 1-2 seasons and are probably the best plug you can get.
4 stroke fuel is not needed any 15-30% nitro fuel will run it, with 30% it will run the smoothest and transition the best. Also Check your top end first and check it with a tach, 4 strokes are hard to tune buy ear and you can be lean on the high end very easily.

What are you running for a prop? If it were me a 15x8apc would be what I would use.

thanks for the tips. it has a 15x8 on it. if it ever stops raining i will try to lean it down some and see what happens. i know its running rich but i was scared to lean it down too much.

Another thing to watch is that many of the P51 ARFs have quite a high tank position. This is fine if you're fitting a 2-stroke engine but often the carby on a 4-stroke ends up much lower than the tank center-line when mounted inverted.

If the carby is too low, fuel will siphon from the tank to the carb. To get the damned things ti idle like this you have to lean them out so much that they end up cutting on transition.

The only reliable solution to this is either the onboard glow or a cline regulator.

Hopefully your tank position isn't so high as to suffer from this problem.