"
My '85 xv1000 backfires when I let off the throttle. It doesn't do it all
the time...sometimes worse than others. I put new plugs in it...didn't
help.
What can cause this?"
I assume you mean out the exhaust. Do you have aftermarket pipes? You
hear it much more with louder pipes, but I think it happens quietly with
the stockers too. Causes (some already have been posted):
Pilot screws too lean.
Exhaust leak at head.
Emissions control - AIS
Regarding the AIS (air injection system), it consists of the chrome pipes
that run from the LH chrome pod to the exhaust ports, as well as the stuff
in the LH pod. It puts air into the exhaust and WILL cause popping on
decel. Plugging that system has no negative repercussions (unless your
state inspection would notice and object) and will decrease this
significantly. The simplest way is to plug its air intake with a thimble -
the intake is a thimble-sized rubber hose, open on one end, on the backside
of the pod. It is totally reversible if you don't like it - just remove
the thimble. On my 87, I removed the whole kit-and-caboodle, and plugged
the holes in the ports with pipe plugs.
One more thing. On 86+ models they installed a Coasting Enrichment (CE)
system. The purpose of this is to reduce that popping for emissions
reasons. Your 85 does not have this feature, meaning it will be a little
more prone to popping.
Jeremy
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