rv4pilott

My Feedback: (1)

Hello, I have a brand new YS DZ70 engine that refuses to start! It is mounted on my test stand like I always do with a new engine for break-in. It will not draw hardly any fuel. The line from the regulator to the high speed needle valve is full of fuel but the line from the needle valve to the head has just a little bit of fuel and a bunch of bubbles. I have tried opening and closing the throttle while turning with the starter to get it to fill that line and fire but not even a pop! This is my second YS so far, having excellent luck with a YS 63. The main needle is open 2 turns as they say and I have tried three turns as well. The plug is an OS F type and brand new. Check it with the igniter and it is fine. Any help you can give is appreciated! Thanks.... Jeff D.

allenpl

Remove HS needle - spin the engine - fuel flow freely?
NO? - check pump/reg output.
YES - disconnect line from barrel to injector - HS say 3 turns open, WOT spin engine - free flow from barrel?
NO? - remove barrel and back flush.
YES - reconnect line and remove injector - spin engine - free flow?.

Fuel system has to be absolutely clean and protected with a suitable filter.

Club member has one of these with this fault from new intermittantly - barrel back flush fixed this one - YMMV

This engine is extremely powerful for it's size and needs careful handling.

IMO using fuel less than 30% nitromethane is not a good idea.

arnstein

Have you tried to increase the pump pressure (turning the regulator clockwise)?
Has your engine a white diaphram?

Arnstein

rv4pilott

My Feedback: (1)

Hi Allen, I did remove the high speed needle and there was hardly anything coming out of it while spinning the engine. At first I disconnected the line from barrel to injector with needle open 3 to 4 turn and almost no fuel flow. I also turned the regulator clockwise (looking at it from front of engine) clockwise almost a full turn. Still no luck. It has to be something in the regulator. Can I unscrew the regulator and take it apart to look for some kind of junk inside it? I put a brand new tank on my test stand for this. Actually the tank is the one that is going in the airplane. Before even fueling the tank I put two brand new filters on my fueling setup and pumped a bunch of fuel through it to make sure the lines were clear, then fueled the tank. It must be something that was in the regulator from manufacturing. Why do you ask it if has a white diaphram? Thanks for your replies, it has to be something in the regulator. Should I take it apart or can it be flushed out? Jeff D

rv4pilott

My Feedback: (1)

Hey all, I found the problem......... I took the rocker arm cover off and saw that the pushrod on the left side was not going up and down while turning the crank. If that does not go up and down the regulator is not being operated ! This engine is going to be sent back! Defective from the factory......... Jeff D

airraptor

My Feedback: (66)

that DZ engine is very strong and even better than the regular 70S in the 8000-9000 rpm range. it will also turn up if needed at 11x14 at 11,000 on 50% nitro.