TT Pro 50 in Rap 50 v2 burnt out

[me]

Hi,

I have just started flying a new Rap 50 V2 with a TT Pro 50 engine. I've had
about 1/2 a gallon o ffuel through it.

The other day, it was noticeable leaning out in the hover, so I put it down
to have a look. The final fuel line from the header tank to the carb was
full of bubbles.

I tried opening up the needle a rew clicks, which helped, but it was
noticeably down on power.

Next flight, same thing, up to a hover, leans out (and climbs quickly), land
and have a look. Bubbles not so visible, so opened the needle a couple more
clicks, and tried again. Now it's over rich, needing about 80% stick to get
off the ground.

Took it back to the shop for their opinion. They found the plug loose, and
reckon that this has been drawing air, and running lean. They reckon the
loss of power is due to the bore wear becoming siginificant as the engine
warms up.

I pulled the engine out, and lifted the head. Head bolts were not tight
(i.e. no 'snap' as they came loose). Visible wear on the chrome in the
liner.

Put it back together, and tried again. after 30 seconds of hovering, power
goes. lots of ubbles in fuel line. Looks like they are travelling from the
engine to the tank.

So, questions -

1. Can a loose plug cause lean running ?
2. Can bore wear lead to pressure travelling backwards from carb to fuel
tank ?
3. As this engine has had only 1/2 a gallon of fuel through, should this be
a warranty replacement ?
4. Anyone got an OS 50 engine for sale ?

TIA

DA

[Douglas Kaip]

I would check the fuel line upstream of where you see the bubbles.
Perhaps your clunk line has a hole or crack in it. Once you find and fix
your air leak set the needles to factory and then try again.

I bought roll of Sullivan fuel line and found it to be defective.
Though normally a good fuel line, the entire roll was filled with pin holes
and it would either weep fuel or allow bubbles like you describe.

Douglas Kaip

[S-Man]

Douglas Kaip wrote:

> I would check the fuel line upstream of where you see the bubbles.
> Perhaps your clunk line has a hole or crack in it. Once you find and fix
> your air leak set the needles to factory and then try again.
>
> I bought roll of Sullivan fuel line and found it to be defective.
> Though normally a good fuel line, the entire roll was filled with pin holes
> and it would either weep fuel or allow bubbles like you describe.
>
> Douglas Kaip

Also make sure the pressure line from the silencer to the main tank is
not leaking. You'll get bubbles in your fuel supply line if you don't
have enough tank pressure.

..S.

[Beav]

"S-Man" <w8an@NOSPAM.sbcglobal.net> wrote in message
news:VTSLc.566$NN7.423@newssvr16.news.prodigy.com. ..

> Also make sure the pressure line from the silencer to the main tank is
> not leaking. You'll get bubbles in your fuel supply line if you don't
> have enough tank pressure.

I wonder how those people who don't use pressure manage then? Pressure (or
lack thereof) will not produce bubbles in the feed line. For there to be
bubbles, there has to be air introduced, and if there's somewhere for the
air to enter the line, then pressure would (if anything) INCREASE the
incidence of bubbles.


--
Beav


Please note my E-mail address is "beavis dot original at ntlworld dot com"
(with the obvious changes)

Beavisland now lives at
www.beavisoriginal.co.uk

[RECKLESS LOONY]

On Thu, 22 Jul 2004 15:09:59 +0100, "me" <me@home.page> wrote:


>Put it back together, and tried again. after 30 seconds of hovering, power
>goes. lots of ubbles in fuel line. Looks like they are travelling from the
>engine to the tank.
>

Your engine is overheating due to lean running hence power loss. You
must get this lean run problem sorted out first then see how the
engine runs.

Hole(s) in tubing as others have mentioned would do it. How is that
clunk in the fuel tank is it fully into the fuel? A bad vibration in
the heli can cause the fuel to foam up I certainly had this problem
once in a Kalt Space Baron when the fuel in the due to vibration ended
going around as if in a washing machine and that resulted in a lot of
air bubbles in the fuel line.

>So, questions -
>
>1. Can a loose plug cause lean running ?

No. A loose glow plug results in loss of compression thus engine rpm
will be down. If you are leaning out which from what you write you are
this will also result in a loss of power.

>2. Can bore wear lead to pressure travelling backwards from carb to fuel
>tank ?

Not a chance. In a two stroke outboard (petrol engine full size) reed
petals are used that close when there is crankcase pressure and open
when there is a vacuum. With our glow engines the crankshaft is hollow
and has a port opening at the carburettor. The crankshaft opening is
mechanically timed such that it is open when the crankcase is at
vacuum and closed when it is at pressure.

>3. As this engine has had only 1/2 a gallon of fuel through, should this be
>a warranty replacement ?

If the engine has been damaged due to lean running then it is operator
abuse and thus NOT a manufacturing defect therefore NO warranty.

>4. Anyone got an OS 50 engine for sale ?
>

I am NOT selling mine. Incidentally I have had at times lean runs
(when setting up) such that the engine got so hot that even killed the
glow plug and I have yet to have an OS engine be damaged due to the
overheating. In one case I had an OS 46 in a plane overheat badly due
to insufficient airflow through the cowl, which I seen rectified. It
also never suffered any damage.

>TIA
>
>DA
>
>

[S-Man]

Beav wrote:
> "S-Man" <w8an@NOSPAM.sbcglobal.net> wrote in message
> news:VTSLc.566$NN7.423@newssvr16.news.prodigy.com. ..
>
>
>>Also make sure the pressure line from the silencer to the main tank is
>>not leaking. You'll get bubbles in your fuel supply line if you don't
>>have enough tank pressure.
>
>
> I wonder how those people who don't use pressure manage then? Pressure (or
> lack thereof) will not produce bubbles in the feed line. For there to be
> bubbles, there has to be air introduced, and if there's somewhere for the
> air to enter the line, then pressure would (if anything) INCREASE the
> incidence of bubbles.

Not sure where it's introduced but it happened to me when a filter
between the silencer and fuel tank was clogged, and just last week saw
it happen to a bud at the flying field when his line was cracked.

Go figure.

[DA]

Hi all,

Iv'e run the Webra 50 a couple of nights now.

Was having trouble setting it up the first night, tomight was soooo
different. I ha dsome help from the guy selling the engine, who's flown
helis for years, and is a huge help.

Now, 3 tanks through it tonoght, and a gooa part of that could have been
using 1 hand. Very smooth and stable. It's set up on the rich side, and is
rough about 30% throttle, which I am happy with whilst I am learning to
hover.

No bubbles in fuel lines now, so I guess the clunk line in the main tank was
the cluprit (coming off). I just wish it had fallen off completely before I
hurt the original engine.

Still waiting for parts for the TT50, which I'll get running and use as a
spare, or maybe use, and keep the webra as a spare - whatever feels right.

Thanks for all the advice so far

Cheers

DA

[RECKLESS LOONY]

On Mon, 26 Jul 2004 22:41:06 +0100, "DA" <me@home> wrote:


>keep the webra as a spare - whatever feels right.
>

Before you decide to acquire that Webra engine I suggest you take off
the crankcase cover plate and have a look at the rear bearing and
crankshaft and see if there is any rust.



Reckless Loony
More reckless and loonier than ever Muhahaha !!

[me]

Will do. Is that a specific Webra issue, or just good common sense when
looking at a second hand, and possibly long-term unused, engine ?


<RECKLESS LOONY> wrote in message
news:4108eb4d.45762203@news.arach.net.au...
> On Mon, 26 Jul 2004 22:41:06 +0100, "DA" <me@home> wrote:
>
>
> >keep the webra as a spare - whatever feels right.
> >
>
> Before you decide to acquire that Webra engine I suggest you take off
> the crankcase cover plate and have a look at the rear bearing and
> crankshaft and see if there is any rust.
>
>
>
> Reckless Loony
> More reckless and loonier than ever Muhahaha !!
>

[RECKLESS LOONY]

On Fri, 30 Jul 2004 11:41:25 +0100, "me" <me@home.page> wrote:

>Will do. Is that a specific Webra issue, or just good common sense when
>looking at a second hand, and possibly long-term unused, engine ?
>
>
It is not specific to the Webra engine but common sense. I have seen a
lot of engines with rust in them due to them being idle for long
periods.

Reckless Loony
More reckless and loonier than ever Muhahaha !!