berge

Hello,
I nave a new os 155 pumped installed in a 1/4 scale Space Walker { engine is inverted} When the the plane is flown through manevures the engine belches smoke and falters when the plane is inverted It comes good as soon as the palne is returned to level flight. BUT once I have used about half the fuel up and fly inverted the engine runs normal and does not falter with very little smoke fram exhaust !!. This is my first pumped motor and I understood that that pumped motors did not suffer these sort of problems The tank is in its normal position behind bulkheadand the center is just above carby. Any suggestions as to the problem ? Thanking you Berge

Bax

My Feedback: (11)

You likely are using fuel tubing that's a bit small. That's why you have positional changes. Enlarge the fuel tubing from the fuel pickup to the engine and you'll likely notice no more difficulties. You may need to drill-out the clunk in the tank to enlarge the fuel passage. Install larger metal tubing in the tank. You may need to replace the tank with one that can take the larger tubing.

berge

Thanking you very much for your reply,I will go ahead with the changes you suggest and will advise . Itcertainly makes sensein what you say. Berge

berge

Made changes as suggested and found a vast improvement.I also leaned out the bottom needle a little more { putting it 1 full turn in from recommended setting !} and all is well . Thanking You for your advise Berge

Bax

My Feedback: (11)

Please realize that "recommended" settings are only starting points. ALL engines will have to be adjusted from there to get the best performance and handling.