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Yes I did gap the plugs properly. This wasnt the first time I had changed
the plugs and I made sure to gap them correctly each time because I have
read other posts from this newsgroup in the past that emphasized that as
well. The caps were also snapped into place properly. However, I gapped
the plugs to .020 and not .015..... I will consider doing that.

I could be wrong (and Im not trying to start a long posting with this
problem) but Im pretty sure it wasnt flooding because it ran a little past
idle (you know, a little past that rough area of idle) and warmed up while I
was at the hangar and then while I taxied down the 3000 ft. runway. At that
point I did my run-up and it started the acceleration normally but then
acted like it wasnt getting enough fuel (in my opinion) as I continued to
advance the throttle. It was definetly hitting on both cylinders because it
wasnt shaking like you would expect with only one cyl. firing.

Thanks for your help.

LS wrote:

> In article <3A39935B.FD03BAEB@cox-internet.com>,
> Scott wrote:
>
> Scott,
> You did say that youd just changed your plugs right before this
> happened. Are you sure you gapped them properly and the caps were secure
> on the plugs? Could have been that, if the gap is too wide, the spark is
> pretty weak...
>
> Frequently, I have to run my 447 with the choke for a while when I first
> start it up. If not, one of the cylinders will "shut off" (due to
> fuel/air mix starvation) as I advance the throttle causing it to bog
> down - it will often do this until mixture finally gets flowing into
> that cylinder in the proper amount. once its warmed up, its ok.
>
> If youre idling too rich, you can get almost exactly the same symptom.
> The engine will be idling along ok, but when you advance the throttle,
> large blobs of fuel that have collected in the crankcase will be blown
> into the cylinder, temporarily dousing the plug and shutting off the
> ignition to that cylinder. Youll barely get above idle and the engine
> will shake like a crack addict in church ;).
>
> This isnt so much of a problem on the dual ignition motors (503 on up),
> or the older points ignition motors, because of the more potent
> ignition. Our little single CDI motors, though, have only that one plug
> that can easily be doused by too much gas, especially at low rpm.
> Running B8EVs gapped at .015 helps a little bit with this.
>
> Just another data point that might help you debug the problem....
>
> LS
> AC fun racer.
>
> > Yeah, that helps a bunch. In some ways, Im glad to hear that it
> could be carb
> > icing. I would rather it be that than compression or fuel problems
> already.
> > Thanks
> >
> > "Fr. John" wrote:
> >
> > > I experienced carb icing with a 503 when I was in Connecticut. The
> engine
> > > was torn down after what you described as "bogging down" happened on
> > > take-off. We managed to get back to the airport. Anyhow, the results
> of the
> > > tear down showed that there was no damage and the only culprit we
> could
> > > point to was carb icing. Hope this helps.
> > >
> > > Fr. John
> > >
> > > "Scott" wrote in message
> > > news:3A3986F3.615D4A67@cox-internet.com...
> > > > Ran-up my Rotax 447 today before takeoff and as I advanced the
> throttle
> > > > to full power, it bogged down like it leaned out. Almost went
> back to
> > > > idle speed....well at least to a low mid-range for a few seconds,
> so I
> > > > aborted the takeoff. Never rolled on the runway. Weather
> conditions
> > > > were favorable for carb ice... which was one individuals
> reasoning.
> > > > Anyone know if carb ice is really a factor with these two-cycle
> > > > engines? It has 50 hours on it since new and has never done that
> > > > before. Fuel and everything else has remained the same. Put in
> new
> > > > plugs before running it up. Taxied it for some time after the
> > > > incident.... ran it up some more and couldnt duplicate the
> problem.
> > > > So, I puddle jumped it down the runway. It continued to perform
> > > > normally. EGT and CHT in normal ranges. Took it around the
> pattern
> > > > after quick visual of fuel lines and fuel pump, and everything
> went
> > > > well. Plugs (in my opinion) appear normal in color. Fuel filter,
> > > > although it has never been changed, appears clear and clean. Carb
> bowl
> > > > revealed no water or particles. Havent changed carb needle
> position or
> > > >
> > > > done anything to the engine that I could attribute to the sudden
> loss of
> > > >
> > > > power. Tightened plugs to proper torque. Getting time to do some
> work
> > > > on the engine I know so, does anyone out there have any
> suggestions on
> > > > why this may have happened or what I should be particularly aware
> of
> > > > when servicing the engine according to the Rotax manual? I would
> > > > appreciate any info. Thanks in advance. Scott
> > > >
> > > >
> > > >
> >
> >
>
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> http://www.deja.com/

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