[Kiwi]

Dick,

Hands down yours is the best advise so far.

I'm on a lunch break so no rambling novels this time but heres my opinion on running in gas engines.

The number one and absolutely critical part is the oil mix. READ THE MANUFACTURERS RECOMMENDATIONS AND DONT MESS WITH IT.

If you happen to be a long way off the beaten track like me and you cannot get lawnboy or Amsoil etc then use the best mineral based two stroke oil you can find. Any reputable chainsaw manufacturer or oil manufacturer will be OK. Remember these guys sell more saw engines than RC will ever see so they know whats cool and whats not. Plus half the RC engines on the market today are built from saw engine barrels and pistons.

DO NOT!!!! run the mixture rich as excess fuel will wash the cylinder walls with the excessive gas and that breaks down the oil film. That equals heat, wear and eventually seizure. But at the same time dont what ever you do run the engine lean. My ideal is to tune the engine so it peaks the high RPM and holds it for 20 seconds or so. The hold is critical as when you bash the throttle to full the engine will suck a slightly richer mixture and you think you have it set. Dont beleive it. Run your full throttle for that 20 seconds and make sure it does not lean out or loose rpm on you.

OK now go fly. The mixture you have just set is all wrong once your flying and the air turbulence, ram air effect etc starts to come into play. Fly your first flight doing some nice easy stuff. No hovering etc. Listen to the engine and vary the throttle use all the way through the range. As often as possible. If your engine burbles a little in the mid range leave it. Dont try to lean it out yet what ever you do. But make sure at your full throttle setting the engine has power and does not fade. Fade is generally a lean mixture. If it fades on a vertical up line land and open the high needle an 1/8th or so. A little at a time is what works. Once your happy that your engine is running good (I did not say perfect) go fly your 5 gallons or so. Every flight the engine will sound better and run better. It will get more and more powerful as the bearings, rings etc bed in. Above all be patient with it.

Another small observation I have made over the eons is when the engine is new you will get a fair amount of black residue in the mufflers. That is normal as all the wearing in is producing a fair percentage of that stuff. Once you get that first three or four gallons through it it will go away and at best you will end up with just black dry soot. When you get that your engine is pretty much ready for the next step.

That means going and adhering strictly to the manufacturers recommendations. If they say 100:1 do it. If they say 80:1 do it.

But most of all tuning a gas engine is a long process. The good part is once you have it you very rarely ever need to go play with it again. It's set for life so to speak.

Now I missed lunch again>!!!


Kiwi