engine woes

[George Kennie]

I purchased an MDS-58 in the spring for my Javelin after purchasing
one at the WRAM show. I selected the MDS because it's almost a 60 in
displacement, but is housed in a small case making it quite light
for the power output.
In it's original configuration it had serious carburetion problems.
Subsequent visits to the local hobby shop disclosed that they were
shipping newer releases with a second generation carburetor touted
as the "C2". Being frustrated with the performance I was receiving I
called the distributor and was advised to return the engine and they
would make it right."Wow!, great service, eh?"  Well 3&1/2 weeks
later I received the engine back with the new "C2" carb installed.
The new unit was about 1/3 larger than the original, requiring
additional cutting of the cowl.Early flights were not perfect which
I attributed to the fact that I had left the adjustments as set by
the distributor, which they recommended. Subsequent flights only
went downhill. Yesterday I decided that I was going to concentrate
on getting this engine finally adjusted correctly. Off to the field
I go and get everything set up." First I'm going to get that low end
spot on and get rid of that hesitation". Fuel it up, turn it over a
couple of revs while choking and yup it's drawing fuel. Attach the
igniter and spin it over with the trusty Kavan and
rrr,rrr,rrr,rrr,rrr,rrr,rrr,rrr,rrr ,.....man, is this thing ever
going to fire? Try a different plug!
rrr,rrr,rrr,rrr,rrr,rrr,rrr,sput,sput, vroom(not a big vroom, I'm
just off idle). Anyhow, I finally got it going enough times to
finally adjust the low end where it would hold idle for a full
minute at about 2K rpm and cleanly transition to full power and do
it consistantly.Aha, I finally got this buggar clicking! O.K., now
I'm going to fly this bird so I proceed to taxi out to the center of
the runway(which takes a few bursts to 1/2 throttle)and advance to
full and the son-of-a-gun quits dead! Stick it back on the bench and
restart it and it still transitions faultlessly from idle to full
power. Go to 1/2  throttle or just a whisker below and it will run
about 20 seconds and abruptly quit. Play around some more and I
finally get it to run at 1/2 throttle for an extended period of
time,but now, when I go from 1/2 to full it quits about 2 clicks
short of full power.Decided that maybe the pressure is too high
causing it to load up at mid-range so I disconnect the pressure line
and try it again. The only difference is that now the high speed
needle is very insensitive, but all the same conditions still exist.

I can only conclude that the carb design is faulty and would warn
prospective buyers to proceed with caution.
I had previously(about a month and a half ago) installed a carb from
a ST-40, which is a perfect fit, and the engine ran well.
I think what I might do is try a Perry, but I need some help with
the Web-site. Can someone help me with that? I think Varsane sold
out to someone named Conelly or something like that.
Thanks for listening to my tale of woe.
Georgie

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