could someone help me out with with my os120 surpass it is broken per manual but when installed in the plane (inverted) it will not idle, any suggestions will greatly appreciated

I would opt for a glow driver, your glow plug is drowning in fuel.

If it's not the pumped version check the height of the fuel tank it should be level with the carburetor.

thanks for the info the fuel tank is set up according to the manual. centre a quarter inch below the needle it just wont idle at less than 4,000 rpm i have leaned it out to the max and worked back up but to no availe

i think your tank needs to be lower.....to check...try adjusting idle mixture with the tank nearly empty....if it idles , then lower tank....i run all inverted engines with at least 2/3 of the tank BELOW the needle in the carb.... I assume that you had it running perfectly in the upright or side-ways position prior to attempting this inverted installation...os #f plug?

Two things, have you adjusted the low end needle and have you replaced your glow plug since you ran it through break in. When ever I break in an engine I replace the original plug with and OS F plug after the break in period.

use a RC long plug for inverted.......

use a RC long plug for inverted.......

If your tank position is satisfactory, then you will want to lean the low end. I suggest leaning low end until you notice that the engine appears to die, but re-ignites. At this point you will want to richen ever so slightly. This will give you the lowest idle rpms. If your idle is not satisfactory at this point, you have only two remaining options. First, tighten your wheels in order to slow your taxi speed to the flight line. Or second, rig an onboard glow driver. The driver is simply a locking glow plug head that is wired to switch and 2000 mah sub-C battery. I use a Radio Shack single sub-C battery holder. The weight is marginal on my quarter scale planes. You can use 1 AA battery but you must charge it after a flight or two. I charge my sub-C with a Sirrius Charger after two or three flights. Hopes this helps.

RevGQ

thanks again for all your help. I ran the motor in on a test in the inverted position and now that I have read these replies realised that the top of the tank was in line with the needle valve,I thought that I would have problems during this but did not, but I installed the tank in the plane as per manufacturers instructions (dumb) I shall have to rebuild my tank mounts in the fuse, but in this balsa usa citabria i have plenty of room to do this, maybe the maiden flight is not so far of as I thought. I'ts nice to be able to bounce things around with like minded folks. again, thanks