Today's Message Index:
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1. 04:33 AM - Re: Dry Black velvet Plugs (Thom Riddle)
2. 05:08 AM - Re: Dry Black velvet Plugs (Rich L)
3. 07:07 AM - Re: Dry Black velvet Plugs (lucien)
4. 02:51 PM - Re: Dry Black velvet Plugs (Roger Lee)
5. 02:56 PM - Re: average water temp of 912/914 (Roger Lee)
6. 03:12 PM - Re: Exhaust Spring (Roger Lee)
Message 1
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| Subject: | Re: Dry Black velvet Plugs |
Don G.
I had the black dry plug problem on both plugs on #1 cylinder only and it took
me a very long time to determine the cause. I had very similar operating conditions
too. I finally found a small gage white wire somewhere in the ignition system
that was not completely broken but partially so. I repaired it and that
fixed the problem. I'm still not sure where schematically the partial break was
in the diagram but repairing it did fix the problem. It is still a mystery to
me how that single white wire could cause BOTH plugs on a single cylinder to
blacken.
--------
Thom Riddle
N221FA Allegro 2000 912UL
N197BG FS1/447
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It has been said that man is a rational animal. All my life I have been searching
for evidence which could support this.
- Bertrand Russell
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Message 2
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| Subject: | Re: Dry Black velvet Plugs |
I have had the same problem on my 912uls since 0 hrs. I also screwed the mixture
in 1/4 turn with no change. I have balanced my carbs twice now and the two
forward cylinders still have the "black velvet plugs". It continues to run great
with 150 hrs on it now and all the numbers are well within specs (EGT,CHT,
Oil & Water Temp, etc).
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Message 3
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| Subject: | Re: Dry Black velvet Plugs |
Rich L wrote:
> I have had the same problem on my 912uls since 0 hrs. I also screwed the mixture
in 1/4 turn with no change. I have balanced my carbs twice now and the two
forward cylinders still have the "black velvet plugs". It continues to run
great with 150 hrs on it now and all the numbers are well within specs (EGT,CHT,
Oil & Water Temp, etc).
I had this problem on my 912uls and there were 2 causes:
- overly rich idle, I have to run my idle mixture screws in 1/2 turn from the recommended
setting (1 turn out overall).
- carburettor vent lines running outside just tucked into the float bowl spring.
The vent lines have to be connected either to the intake airbox if you have
one or routed into the air filters if you run those. The carburettors will run
rich (and very much so at higher altitudes) unless the vents are at the same
atmospheric pressure as the intakes in front of the venturis. This requirement
is in the Rotax documentation. I bought some brass fittings at lowes and put
them into holes in the back of my air filters. Fixed the rich running completely.
The cylinders closer to the gearbox do run a little richer than the other two on
my motor as well, probably due to slightly different lengths of the intake runners
for the two banks of cylinders......
LS
--------
LS
FS II
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Message 4
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| Subject: | Re: Dry Black velvet Plugs |
Hi Guys,
The length of the intake manifolds combined with each of our different engine setups
in different planes can cause our plugs to look different and even have
that dry black velvet coating. You won't have that when you are running at operational
speeds (i.e. 4800-5200rpm). This is usually caused in the low rpm range.
There can be more than one cause. Try one cure at a time until it goes away.
If it doesn't don't panic your engine still runs good as many people will
attest to.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Service Center
520-574-1080
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Message 5
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| Subject: | Re: average water temp of 912/914 |
180F-220F is very normal for this time of year. If you are using a 50/50 coolant
then 248F is max. In the winter it might be lower in the 165F range. In the
winter the warmer the better (i.e. 180F-220F)
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Service Center
520-574-1080
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http://forums.matronics.com/viewtopic.php?p=188821#188821
Message 6
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| Subject: | Re: Exhaust Spring |
Roughly how many hours on each set of springs? Like Guy stated, make sure you use
a nice thick wide bead of hight temp silicone pressed into and on each spring.
When they are getting worn through then the mounting loops and the springs
just have to be changed. Make sure all of you have these springs safety wired.
The wire goes through the center of the spring and around each mounting loop.
The safety wire should be slightly lose as it is not meant to hold the exhaust
together and need to be able to move some. The safety wire keeps the springs
from going places you don't want them if they break or come off. Use the .041
wire. Are the springs strung too tight?
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Service Center
520-574-1080
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http://forums.matronics.com/viewtopic.php?p=188823#188823
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