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Yamaha XS650 help needed
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I have a 1980 XS 650 sidecar rig in need of some diagnostic expertise.
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Have you talked to the folks at the Society of the 650?
How about the XS650 discussion group?
Sometimes a marque/model expert can be really valuable. Good luck!
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Cutting to the case.....it runs at idle, but will not rev beyond idle. It
just falls flat on its face. Burbles, pops, spits. The problem started
about 5 miles after filling the tank. Cleared up briefly, than reverted back
to the not running above idle. I drained the tank and put in fresh gas. I
pulled the carbs X2 and cleaned them to no avail. I replaced the CDI unit
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You could have petcock flow problems... verify
that fuel gushes out the petcocks when on. This
is not as simple as it sounds, since your bike (I
owned a '79) has vacuum-operated fuel. See
if the symptoms go away when you turn the
petcocks from Auto to On. My XS petcocks
ended up giving up the ghost when I ran
gasahol through them... had to glue up the
weep holes with epoxy and use them manually
from then on.
You could also have fuel passages or jets plugged...
the low-speed mixture needles may need to come
out. Did you find lots of grot in the fuel bowls?
Look for symptoms of rich or lean... the 'pop'
sounds lean, the 'spit' sounds rich... more research
is necessary.
__
Steve
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suspecting there was a problem with the ignition not advancing. I have had a
CDI unit puke before causing intermittent problems. . I can pull either
plug wire and the revs drop, from idle, the same amount. What ever the
problem is, it effects both cylinders equally. I see a strong spark at the
plug at idle, and it weakens as I attempt to rev the engine. I have cleaned
the plugs and tried a fresh battery. Actually, I run it off a car battery
in the sidecar trunk. Coil, perhaps? Also, I do not think there is a
problem with the tank petcock. I tried running the bike with the petcock
set in the prime position. Any help much appreciated. I cannot afford to
take it to a shop, but I really would like to get the beast running again.
FYI, here is a link to pictures of the rig.
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I had an old van that sat in my driveway for a few years before I got
around to getting it ready to sell. It would hardly run above an idle
too. It turned out that all the rust that had accumulated in the exhaust
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Hi Steve,
Yea, I ran the bike with the petcock on 'prime' and gas flowed freely. When
I pulled the carbs, I did not not see any junk in the bowls and I cleaned
the jets. The thing that makes me think it may be an electrical issue is
the fact that both cylinders seem to be equally effected and both carbs seem
to be getting gas. If one carb was junked up, I should still be able to rev
a bit above idle. But there again.......
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How do the plugs look? Got timing light?
Verify the centrifugal advance/points are OK...
check battery voltage. You may have done
the headlight switch mod... does it idle the
same with the headlight on? GL...
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blew into the catalytic converter when I started it, plugging the exhaust.
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Hi Steve,
The plugs look good. First, I cleaned them. Later, I had one spare new
plug, and tried it, also. No points and condensor on the
bike.....electronic ignition (CDI)....replaced it X2 with used units....no
such thing as a new CDI, anymore. Lights are bright and the horn is loud. I
have an air horn as well as a bright running light on the sidecar. Tried a
known good car battery just recently, too.
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Don't know how your exhaust could have plugged up.
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