[NSRCA-discussion] Question - YS140DZ

Mon Jul 21 19:22:08 AKDT 2008

Chin cowl
YES
Happened when I pulled trim to cut the engine

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From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of
adriancwong at earthlink.net
Sent: Monday, July 21, 2008 10:17 PM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] Question - YS140DZ

What do you mean by a bump? Engine bangs the chin cowl/ bellypan and cause
the damage? If in the affirmative, it usually happens when it's ran out of
fuel or on the lean side

Adrian

-----Original Message----- 
From: Lisa & Larry 
Sent: Jul 21, 2008 8:00 PM 
To: 'General pattern discussion' 
Subject: Re: [NSRCA-discussion] Question - YS140DZ 

Finally dug into this

Yep, it was the ole thrust washer and engine RPM turning faster than the
prop and spinner wanted to go

Root-Cause
After getting a new TT spinner and adapter kit and new large
thrust washer, it was obvious, I was not using the same type of lock nut
adapter kit as the replacement. Although locked, it wasn’t snug against the
prop.

Ran the 140DZ today and had a few DZ bumps during the high speed needle
adjustments, but everything held tight together and I got the high end close
now.

Turning an APC 16x11 at 8,500 RPM on Power Master 30% DZ. About 90 degrees
and very humid 80+
I suppose this is about average RPM.

The plane is a Titan is a wood kit and is 10-¼ pounds so this should be
plenty of power for Intermediate
Hopefully well get some flights in this
weekend

I still get a little bump when I cut power
What causes this
?

One was a huge bump and popped the side of the fuse
Minor damage and low
weight repair
some CA and covering

Larry Diamond

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From: Lisa & Larry [mailto:lld613 at psci.net] 
Sent: Monday, June 02, 2008 8:45 PM
To: 'General pattern discussion'
Subject: RE: [NSRCA-discussion] Question - YS140DZ

Thanks Adrian and Troy

I’ll try the sand paper trick and check everything out. I’ll also check
where my needle valve is at...

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From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Troy Newman
Sent: Monday, June 02, 2008 8:13 PM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] Question - YS140DZ

Sounds like the prop slipped on the thrust washer like Adrian stated. This
can happen. Try one of the Central Hobbies large diameter thrust washers...I
used these when we ran the 140DZ's

The 160s and 170s changed the the thrust washer to make it more aggressive
bite on the spinner. The slip will happen then the aggressive bite that is
there gets smoothed off and then its tough to get it to bite properly again.

Another little trick is to tighten the prop...run the engine a little and
get everything heated up...then stop it...Tighten the prop up again and lock
the double jam nut down onto it. Your collet behind the thrust washer can
get compressed a little and it will actually slip if the engine backfires.
Its because the collet is compressed X number of times and the grip on the
taper is not as good. This is usually only a  problem when the  when you
have had the thrust washer off the engine and the first time you tighten it
back up. If the thrust washer has not been removed from the collet then its
probably not the issue...

We did the Central Hobbies thrust washer in order to give a bigger diameter
to bite the spinner.

http://www.centralhobbies.com/engines/ys/biggrip.html

It works well. Not trying to pimp the product but it was designed to solve
this problem and also the bigger hub 3D props had this problem too. The
160's and 170's don't tend to suffer from this as much. The 140DZ has a good
bit of compression and tends to have a bigger kick....so the it can throw
the spinners loose more that the others. 

Another issue could be a little lean on the pump....this would make it
detonate a little on the throttle up. Try richen the pump just a  little bit
1/8th of a turn or so CW or (IN) if the engine is sounding a little harsh or
hollow when throttling up. 

Your choice of prop is good in that its not loading the engine too hard. The
higher loaded props will tend to spit harder when you run it out of fuel or
the engine starves and goes lean.

Check you fuel filters..if they are clogged up then you can get reduced fuel
flow and it will make the engine go lean for a split second on the throttle
up. Its amazing what a small piece of lint can do. If your fuel filter is
the screw together type check it to make sure its tight and not pinching the
o-ring to allow an air leak.

Fuel lines or tank can have a small air leak and get an air bubble in the
line causing the burp....If it burps in the air..check the prop for tight
the next you fly it. Chances are it might have slipped a little.

I have used about 60grit cloth backing sandpaper like Adrian stated, Put two
pieces back to back and CA them with thin CA and it makes a good surface
area grip. Another option is a small disk of aircraft ply like 1/8th soaked
in thin CA with the sand paper on both sides. Tighten it to compressed the
wood then CA it again and then tighten the prop back up.

Like I said the 160's and 170's are lower compression engines and don't tend
to suffer from this kickback issue as bad. In fact I have not had any
problem with it the last few years. 

You can reduce the kick on the 140DZ by removing the crank shaft ring. This
will reduce the power a little but makes the engine run smoother less
vibration and less kick if it gets an air bubble.

Also are you running the YS Bubbless tank pickup (Foam clunk) you should be
if you are not already. Talked to a buddy today that was running a 140 Sport
and put a 140DZ in his model. The foam clunk seems light but when it gets
fuel in it the weight is proper to keep it in the fuel all the time.

As always check screws, on the carb, head bolts, backplate, valve cover and
so on. An air leak from a loose screw will make the engine go lean. Not
always kickback...but it could and be causing the problem.

I hope this helps.

Troy Newman

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From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Lisa & Larry
Sent: Monday, June 02, 2008 4:41 PM
To: 'General pattern discussion'
Subject: [NSRCA-discussion] Question - YS140DZ

Ran the engine at home about three weeks ago and perfect idle, midrange, and
full throttle... 

I went to the field Sunday to maiden my Titan
Started as it usually does,
and while it was at idle I adjusted the transmitter to get it dialed in
after my Tx repair / reprogramming. This took about 15 to 20 seconds
Let it
warm up a little longer and then slowly increased rpm
About ½ throttle on
the stick, somewhere between 5,000 and 7,000 RPM I heard a low freq buzz
(sounded like an electric motor burning up
vbg)
shut it down and found that
the spinner loose (new spinner, new prop APC 16 x 11). This is the set up I
have flown with this engine for 3 years

Tightened up the spinner making sure the prop was tight and started again
and got a DZ bump
nicked spinner, not bad
Tightened everything up again,
started nice idled well, then transitioned to full throttle. Again at half
throttle, it popped, quit, and shavings of prop flew every where. It was
violent. The spinner is bent worse than I ever saw before by anyone
The prop
was intact except for the missing chunks at the hub where it hit the
spinner.

Starting procedures and equipment:

Radio South Starter with on/off switch in the off position, using a Kavan
starter turn the prop and then turn on the Ni-starter. Temperature was about
20 degree warmer on Sunday than the initial test run. Used the same fuel
from the same can, Power Master 30% DZ

Three weeks ago it was running a bit on the rich side and I didn’t touch
anything until Sunday when I intended to lean it out
Never got that far.

What did I do wrong if anything? What can I look for in the engine to repair
or correct myself or looking at?

Or do I just send it in to YS Performance?

I have a back up 140DZ and bought the last FAI 3-¼ TT spinner w/ light
backplate at Central
vbg

If I made a mistake, I don’t want to repeat it.

Your thoughts? Troy you out there?

Larry Diamond

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