I have a 140 DZ that has been going through plugs at a rate of 1 every two flights. Went out this weekend and went through 5 plugs! Two weeks ago I went through 3. Both YS and OS F plugs, doesn't seem to matter. The problem seems to have gotten worse since I switched fuels. I used to run Coolpower 30% Heli and recently swicthed to PowerMaster 30% DZ blend. I did burn plugs also with Coolpower, but not like with the PM DZ.

Here are some specifics that may help:

YS 140 DZ
prop: APC 16-12
Plugs used: YS and OS F
Pump setting: 1/2 turn IN (rich) from flush
needle setting: 2 clicks shy (lean) of 2 turns
Static WOT RPM: 8400
Elevation: 5300 ft.

With respect to the needle setting, I do seem to have a funny "double peak", one at the above setting and another at about 2-3/4 turns out. However the richer setting is slightly less in RPM (8200) and feels too rich in flight (loads up during throttle up and leaves a lot of smoke trail)
I have tried to go leaner, but I get detonation and and some banging at the mid-range transition. It really doesn't like to run at anything less than what I have listed. I have heard of others at my altitude running much leaner than this (1 to 1.25 tuns on the needle).

I haven't messed much with the pump....I have run it flush and 1/2 turn IN from flush, where it seems to work a bit better (better transition from idle).

Any suggestions??

Thanks,
-Erik

Dr Erik Richard,

long time no talk brother. Good to see you are still in the modeling group up there in Colorado. I'm in PHX AZ area now.

On your DZ:

Try going a bit richer (IN) on the pump. The funny double peak thing is common on the 140DZ's...You are likely a little lean. Since the needle has very little response from the 2.75 to 2 turns open the 2 clicks is probably a little lean.

Also a concern is metal floating around inside the engine. This will eat plugs as well. Bad bearings and the likes can be hard on plugs too.

I would richen the pump (IN-CW) say 1/2 turn and then re-peak Back it off about 200 -300 rpm from that peak value. It might be 3-4 clicks rather than 2 clicks. The 140DZ has a pretty flat spot on the needle like you describe. The too rich to too lean is a broad band say 1/2 too or more but you want to be closer to the lean side than the rich side.

I don't have any direct experience with the newer PowerMaster DZ blends...I had trouble early on 2002 and went to the Cool Power from the Powermaster at the time. I'm sure the newer stuff for the DZ's Powermaster is good...I know a few guys that are running it. Mark Atwood (ohio) is one and I also Dave Villwok (Pac Northwest) was running PowerMaster as well.


I always found my 140DZ ran best a little richer on the pump and a little leaner on the HS. I was around 1.25 turns on the HS and about 1/2 to 1 turn in from flush on the pump.


Try that and let me know. You can find me over in the YS engine forum regularly. I don't always hit the pattern forum forum...but I have been helping out Richard and YS Parts and Service over in the RCU YS forum for a little over a year now.


Troy Newman