Help required OS 70 - 4 Stoke (Acro WOT)

Sorry Lee, I didn't mean to sound too technical. One thing that came to mind is............Can you see the throttle barrel through the carburettor intake? Does it rotate OK when you operate the throttle stick? More important, can you see a hole the same size as the intake when you open the throttle? If not, go to the menu on your transmitter and reverse the throttle servo. I mentioned the "clunk" this is the weighted end of the fuel line inside the tank. Sometimes in a vigorous "arrival" the clunk gets pitched towards the front of the tank. This means that fuel can't get through because the clunk isn't down in the rear of the tank. Check with an empty tank, hold the model nose up and give it a good shake from side to side, you should be able to hear the clunk rattling. If it doesn't, a couple of sharp taps with your hand on the fuselage side close to the engine should dislodge it. One more thing might help. Perhaps there's some dirt around, either in the clunk inlet or, more likely in the carburettor. Take off the fuel line, remove the main needle, attach a clean piece of fuel tube to the nipple on the carb, and blow. Just one more thing, OS four strokes seem to like OS F plugs best, expensive but reliable.

Brian, I will refer back to my earlier post,

Quote" I did say you needed to sort that throttle linkage out. If it was to start you may find it is going flat out or at least half chat and not an ideal surprise. That prop is also a scythe and not forgiving. The carb barrel is not getting full travel and by the look of it, it isn't closing down to an idle position either. The throttle control rod link is hitting the engine mount bolt. This is because the carb has been turned round"

Carb and throttle need sorting first. Then whilst the engine is off, check fuel lines. Without having full control of throttle he will be going round and round in circles. That's my 5 penny's worth.

Should have read the whole thread, sorry Phil.

ok update:

Me and john been playing for couple hours, cowl off etc etc, stripped right back now.

Found out the throttle servo needed reversing as open was closed closed was open, so at least now its going the right way,
still not starting though !!!! doesn't seem to draw fuel in?? and now it seems to be almost locking up, I remember phil mentioning something like hydrostatic locking!

So back to the drawing board and more scratching of heads !

I am trying to picture in my mind how far you have got. It is a not easy to help when not able to see the animal in the flesh.

Okay, so the throttle barrel is now shutting closed and when at full throttle the link stop just hits the engine bolt now I imagine? Yes?

Not drawing fuel? It must be if your getting hydralock (excess fuel in cylinder). Don't force the engine over compression, you may bend the conrod. Either pull the glow plug out and flick it over or wind carefully backwards so that the exhaust valve opens and dumps the fuel out through the exhaust.

Are you able to creep up to the field Tuesday? I should be there most of the day.

We know you have good compression so valve clearances are acceptable.

yes valve open right way now the throttle servo is reversed , getting worried about this locking up though :dry: