#1: 82 XV750 front cylinder not firing
(SOLVED) Author: mkelsho, Posted: Thu Jun 03, 2010
2:22 pm
My xv750 misses under 3000rpm.
At idle its like the front cylinder isnt even firing. If i give it slight
throttle, and put my hand over that cylinders exhaust i can feel the
random bursts of heat and compression, but at high revs, the engine doesnt
skip a beat, but takes its sweet time returning to idle. On top of that, i
get a constant backfire/popping from that cylinder. No matter what, even
at idle. I can stop the backfiring by setting the pilot over 4 turns out,
but doesnt effect the sputtering. Ive tried everything, ive checked for
vacuum leaks, with carb spray and propane, removed the mcv, put the mcv
back on (the only thing that concerns me about that is on the vacuum line
there is a T connector with one end of the connector has a pin hole, and
the other two ends are normal size, im not sure if the pin hole goes
towards the carb, the mcv, or the petcock), cleaned (x4)/sync the carbs,
new o-rings on manifolds, wd40 all connections, moved the ground wire,
switched the coils, replaced spark plugs/wires, brand new battery. I
thought it might be the battery, so i hooked up a jumper pack to the bike
with no change. I also checked for spark, it is constant. I thought maybe
weak spark, but even with a weak spark, i shouldnt be getting cold air out
of the exhaust. I havnt checked compression, but i assume if it were
mechanical, i would have problems at all rpms. If i give it a little
choke, she runs perfect. Im not sure what else to do, this has to be
fixable. I need help please
Last
edited by mkelsho on Mon Jun 07, 2010 2:06 pm; edited 1 time in
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