tuning an O.S. 46 LA

[luke]

hi ,
ever since ive owned the 46 la engine i find it almost impossible to tune it correctly. :!:
i have other O.S. engines (.25 fx, .91fx, 1.20 fx and never had a problem tuning them, the difference is that when leaning out the engine , you can definitely hear a pitch change.
but when leaning out the 46 you keep leaning it out , and dont hear a pitch change at all !
and what i find aswell is that to get it to run properly you have to make it run terribly rich.and if you tune it to where it should be the head of the engine gets very hot.
by the way i was using an 11x6 prop , i wander should i try the 10x6 or an 11x5 prop.
or has anyone had a similar experience , or know of a trick to tune it properly. mabey its just the l.a. series of engine
thanks
luke

[Fred]

Hey Luke,

Hmmm, I haven't touched a .46 for years now, but I guess you already checked the basics and seeing your list of engines, you know how to tune them   .

Just in case, check carburator + needle for dirt etc etc
Change the plug (to hot if that was a cold, to cold if that was a hot...)
Change the fuel, 0 or 5% nitro (don't know what you are using right now)
Is that a brand new engine ? the running in has been made properly ? Might need more...
Check for any defects, traces on the O ring, piston etc etc.
Check for leaks on the cylinder, carb etc etc...

And let us know !  :?:

In 23 or 24 years of modeling, I only have 1 engine that never run for more than 30 seconds... :evil:  :evil:  That was a Magnum 46.. Tried absolutely everything possible, spent days on it...
Finally, went back to the dealer to have another one... Running fine this time! It seems that one serie had a known defect... :!:  :!:

Hope this help

Fred

[luke]

hi fred.
ok the facts :
fuel: 5%
glowplug an OS no 8
the engine probably has had mabey 4-5 hrs use
looking through the manual, it seems that i may need a tacho to tune it right, its rated for an rpm of 15,000 at optimum settings , but this cannot be reached when stationary , it seems that in the air the motor unwinds and THEN reaches th 15,000 rpm , ah i dont know , its kinda pissin me off at the moment :evil:

[Bill Hodges]

I had basically the same problem with an LA 46.  I found that I had an air leak around the carb.  I sealed the gap between the carb and crankcase with high temp silicone and the problem disappeared.

Bill Hodges

[JohnPearson]

Hi luke

I had a SC 53 ABC which when you adjusted the high speed needle, it would never reach the top revs. I checked the engine over, stripped the cab down and cleaned it, used various props etc and 10% fuel, still no good. I solved the problem by borrowing a cab from a friend with a simliar engine, tried it and the engine ran sweet. The problem was in the cab, just poor quality in the manufacture.

johnp