#1: Really Strange Problem With 2005
Virago 250 [SOLVED] Author: lub997,  Posted: Fri Apr 09, 2010
3:36 am
I am having a really strange
problem with my 2005 Virago 250. I started it up last winter on an
extremely cold day and it didn't seem to be running quite right and I
figured it was just because of the cold as it usually takes a long time to
warm up unless it is 90 degrees outside, which it of course wasn't, so I
rode it anyway and it did not get better as it warmed up and I ended up
completely losing all power about 20 miles from home and had to ride it
home going 10 miles per hour on the side of the highway because that was
all the power it had. It was still running though. Upon getting it home
and inspecting it I noticed that I could hear a strange noise as if the
cylinder were opened up and I could hear the inside of the engine. It was
a sound a lot like the sound that happens if a spark plug comes out on a
car engine while it's being driven if anyone has ever heard that noise. I
also noticed that the plastic intake manifold was getting some pretty bad
cracks in it, so I figured that was likely the problem as that explains
both power loss and being able to hear the inside of the motor. So, I
ordered a new intake and put it on, only to find that now it would not run
at all, so I checked the compression and the rear cylinder had wonderful
compression, but the front cylinder had very low compression, so I took it
apart and figured out that the exhaust valve was bent, so I got that
replaced and got the valve seat machined and it was still low on
compression, but was able to run now. It would only run on the rear
cylinder though. The front was still not working. I could tell this
because if I removed the spark plug wire on the front cylinder it made
absolutely no difference in how the engine ran. It was clear that it was
only running on the rear cylinder. The rear cylinder appeared to be
running quite well though. So, I took apart the front cylinder again and
found that the intake valve was also ever so slightly damaged, and it was
enough that it was affecting the compression, so I replaced the intake
valve too, and put it all back together, and even cleaned the carb and
replaced the air filter and the spark plugs just for good measure, and now
the front cylinder runs wonderfully, but the rear cylinder appears not to
be running. The front cylinder warms up, but the rear cylinder feels cold
to the touch and if you remove the spark plug wire on the rear cylinder
now, it seems to make no difference in the way the engine runs, as if it
is running only on the front cylinder now. This makes completely no sense
since I changed nothing about the rear cylinder which was originally
running great. I have checked the spark on both cylinders, the timing on
both cylinders (both the marks on the cam gears and at the viewing hole on
the magneto), adjusted the valves on both cylinders, it has to be getting
air and fuel or the front cylinder wouldn't be running. I have even tried
removing the fuel tank and seat to inspect all the wires to make sure none
have any bare spots grounding out on anything, and none were. It has all
of the elements that are supposed to make an engine run, spark, timing,
compression, fuel, and air, and yet it is only running on one cylinder
which makes no sense as the one that appears not to be working is the one
that was running perfectly and I changed nothing about it. Currently the
compression is wonderful in both cylinders, it still appears to be running
on the front cylinder only, idles wonderfully, and dies if you give it any
gas, even if you adjust the choke. I wouldn't think it could be a
carburetion issue as it has one shared carb that is split off to both
cylinders by the intake manifold, so if the carb is working well enough to
run one cylinder logically it ought to be working well enough to run the
other cylinder as well. I am out of ideas, and would like to hear any
ideas anyone else might have.
Last
edited by lub997 on Sat Apr 10, 2010 8:47 am; edited 1 time in
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