geo29

This my first 4 stroke engine and I'm having problems getting it to run properly. It will idle good but it isn't very smooth at full throttle and the transition from idle to full is always sluggish. If you leave it run at about 1/2 to 2/3 throttle it sounds like it is labouring. Adjusting the needle valve and idle setting doesn't seem to help and I've tried adjusting the valves which hasn't helped either. Perhaps I am not adjusting them properly.
Any help, tricks, or tips would be greatly appreciated. By the way, it has an OS type F glow plug and for fuel I'm using Omega 15%.

Thanks.[img]i/expressions/face-icon-small-confused.gif[/img]

TimC

Is this a new engine geo29? This sounds like maybe your too rich on the idle mixture. The idle screw effects the mixture up to about 80% throttle. The manual gives good directions for valve adjustment. The fuel and plug choice sound good. Poor compression shows up at idle first, so that's probably o.k. If it's a used engine, maybe the bearings should be looked at. Run it wide open and lean it for max rpm, then richen it for about a 300 rpm drop. Now adjust the idle for a good transition. If it burbles with lots of smoke, lean it some. If it bogs down or dies with no smoke, richen it some. A 1/8 turn on the idle screw at a time is about right. I use an 11x7 MA on my .52.

geo29

Thanks for the tips. It's fairly new.....about 10-12 tanks run through it with an APC 11x8. I'll try and set the idle mixture and see what happens.

ballgunner

My Feedback: (1)

Four strokers seem to be inordinately slow to break in. Mine, a Magnum .52 took almost 6 months of flying to reach its peak. The difference between the Magnum and an OS is negligible after the same length of breakin.
It just seemed like an eternity before it jumped up to top performance and then it just happened between one flight and the next. OS the same way. Have patience.

rctrax

One thing I could say is make sure you have adequate exhaust valve clearence. Make it on the high side of the tolerance window[.008 or .009] rather down near .004. I have one of these engines and it gave me so much trouble at one time that I was ready to throw it away. until a friend suggested I set the exhaust valve clearance open more. That made a new engine out of it. It now flies flawlessly. I fly it every day. Some of those engines were quite sensitive to valve tolerance.

geo29

Well, I re-adjusted the exhaust valve and re-adjusted the idle mixture and the engine work excellent. Thanks for the help.