Hi All,
I have fit a YS DZ 170 into a Black magic and have been struggling to get everything running this season so far. After a few setup errors, I finally got the engine to start up, but it only runs for a few seconds and then very abruptly dies. I also tried to bump the throttle a few times and that always was met with a strong ending that appears to backfire as the spinner was knocked loose.

I am running a 19X11 APC, on Cool power 20% heli fuel

Before start of this season, I sent the motor to Richard at YS performance and had him replace anything not up to snuff (new pump diaphragm, new read main bearing) and run the motor to insure it ran OK

I did not touch anything during these attempts, other than to start with the high end needle to between 2 and 3 full turns out

The backfire leads me to believe I am lean on the low end, but I am not very experienced on these engines - I know there is a regulator screw that functions somewhat as a low end mixture - The screw is currently flush with the housing, per Richard's suggestion and the way I got it

I have not been able to get the motor to run more than 5-10 seconds without loosening the prop, or spinner accompanied by an abrupt end each time

Any suggestions out there? - I really want to make a go of my older 2 Meter ship on glow - just for sport flying

Thanks to all who respond

(1) Ask Richard what fuel he used and what prop he ran on it would be a good start.

However, if it's an pre-low oil, pre-cdi (ie early glow) DZ170 then a 19x11 is a bit on the large size, and dropping back to something around a 17x13 or similar might help?

I have a DZ170cdi and the regulator needed to be turned out from flush well over 1/2 a turn and the main needle set to about 3/4 turn out. I've never run mine on Glow but the guys who have seem to suggest running the main needle around 1.5 turns out. Somebody may correct me on that though.

When I've had a horrible time finding an initial setting for the regulator, I've found starting the engine at the desired higher throttle setting helps rather than trying to bump the throttle while it's running, but again I've only ever done this with the CDI version.

I hope some of this helps??

The trouble with adjusting YS 160 and 170 is that if you have the high end needle to much out - like more than 2 turns you have to decrease the pump by turning it counter clockwise for running smooth on idle and vice versa. As mentioned above - set the high end needle somewhere around 1,75 turn out and the pump is setted so halv the cone part of the pump adjustmend is visible - like 1 - 2 mm out of the "house"

In the instruction manual I think there are stated that you have to set the full throtle adjustment first and then adjust the pump thereafter to have smooth and low idle and smooth transistion from idle to full throtle.

I ran my YS on 17 x 13 and 18,1 x 10 (APC).

Good luck with your YS

Definitely lean on the low end. The reg screw position sounds about right though, so maybe a blockage/restriction somewhere?

FYI - Glow versions need to be 1/2 turn richer on the reg.

If it ran well for Rich, then I would check your fuel system (tank and plumbing) before you start 'adjusting' the engine. And definitely check with Rich for the fuel (nitro and oil %s) and prop he used.
Good Luck!

Ah, yep. I missed the bit about Richard running it.

So it could be a plumbing issue or maybe a blocked fuel filter.

Also, if the 19 x 11 is bigger, then that would make it run lean.

Funny story with my new DZ200cdi I sent back to YS japan 'cos it wouldn't idle as I thought it should.

I got the "runs fine, no problems to see here" story and they sent it back. The prop driver FELL OFF when I took it out of the box??
For my sanity, I've decided I just don't want to know what happened to that engine in Japan...

A loose driver is fairly common. They don't always lock up tight. Don't have too really.