riot3d
Posts: 953
Score: 100 Joined: 2/8/2005 Last Login: 5/20/2013 From: oakland,
CA, USA Status: offline
|
Taylor, I'm surprise that you're having so much trouble with the 170. The original 140 DZ did have some issues, but was fixed when the 160 came out. The 170 - both the regular & the cdi version has been bulletproof for me - & the 175 is even better. Let me ask you a few questions:- 1) Did you ever break-in your engine on a test stand? If yes, for how long & how much fuel? I usually put in at least a gallon of fuel on a stand, get to know both the high & low settings well, before installing it onto the plane. Once installed onto the plane, it usually only takes me about five minutes to fine tune the pump & will be ready for flying. 2) Assuming the engine is broken in on a stand, did you ever check the valve clearance before your first flight? The way you check them is to turn the prop until the valves are in top dead center (TDC), then grab the front & back of the tappet & rock it back & forth, there should not be any play on both intake & exhaust. However, don't over tighten them. 3) You mentioned you've changed the regulator, does it mean the diaphram, or, the whole pump? If it's the diaphram, where is the adjusting screw now? If you already have hundreds of flights, then I will suggest changing the regulator spring, the pump valve springs & the pump valve as well. 4) At this point, I suggest returning everything back to factory default - high speed needle at 2 turns, pump adjusting screw flush with housing & run the engine again. Also check all of the screws - throttle body, head ...etc. Make sure they are all snug but not over tighten. Also, check the filter & fuel lines. After you have started the engine, let it warm up by gradually advancing to full throttle. Adjust your high needle to max rpm, then back off about a 1/4 turn. Point the nose upward to 45 degrees at idle, if it speeds up, richen the pump. If it slows down, lean the pump - 1/8 turn at a time. 5) Depends on what size of prop you're using, 7,600 is ok but sounded like a bit under prop to me, & 2,300 idle is too fast. If it is properly adjusted, you should be able to slow it down to 1,800. I'm using a 20x10.5 PN on 30% heli fuel, maxed at 7,100, idle at 1,700. 6) The foam clunk will definitely help, but shouldn't affect the engine that much. 7) When you raise the nose of your plane, does the idling speeds up, or, gradually slowing down before it stops running. If it speeds up, the pump is lean. It sounded like the engine is not yet fully broken in, hence giving you all the problem. Be advised, when you tune the engine on the ground, make sure either the bellypan or chin cowl is off. Otherwise, you can over heat the pump & making it runs erratically. Hope this helps. Adrian
Hide Signatures
|