Exhaust popping on decelleration...

Okay, admitedly, I'm a green newbie at engines and wrench work.
Since getting my bike, I've taken a slight interest in doing some
of the work that it needs myself ($60 an hour? ouch!). I had
the bike (1980 GS1100L) serviced, and the mechanic said he could
not do much to adjust the carbs because the boots on them are leaking
a lot of air. I know I need to get these boots replaced, I just
need to find the time.

Okay, now to the question for you gearheads out there. Can
the engine running lean cause the bike to "pop" out the exhaust
a lot when decelerrating? When I'm going at a good clip and then
just totally let off the throttle, the exhaust goes pop-pop-poppop-
pop-poppop... Is this a symptom of running too lean, or do I need
to look elsewhere?

Thanks!

- Eric

 

I had the same problem with my Yamaha XS750. I took the carbs off and
cleaned them really well, changed the plugs, ran super unleaded gas + gas
treatment through the tank. In the end, I couldn't get rid of the popping
noise. I found it is easier to tell people that you adjusted it that way on
purpose because it sounds cool.

Joe

 

The air getting in past the boots is responsible for the pop. Replace
the boots.

Charles

 

When you figure it out, could you let the rest of us know? There have
been plenty of people trying to get their motorcycles to make those
sounds, and their's just run too good and keep idling down like
they're supposed to.

Any help with getting a bike to do what yours is doing would be
appreciated.

 

The Suzuki Savage 650 Single (all model years) also backfires upon
deceleration and the common theory is that EPA-mandated carb mixture
settings (too lean) are the culprit.

At least your bike doesn't have the mixture adjustment screw plugged with
brass to avoid owner tampering. I'm going to Dremel mine out when I've got
some time to kill...

However, in your situation it could well be the carb boots.


--
Dirk
(aka "!bungle")
'96 LS650
(aka "Rhino")



"Well, you may be a lover but you ain't no d-d-dancer"

 

Haha. I'll let you know.

Thanks to everyone for the tips! I'll replace the carb boots as
soon as possible. If that doesn't fix it, I'll look at adjusting
the carbs, etc. Now I just have to find the time. ;-)

- Eric, destined for an auto shop for radiator hose in the near
future to replace the carb boots. heh

 

87 Honda Rebal, great starter bike, it's been starting for 3 yrs.
Only have to lean out the carb very 30 miles or less to keep it
from poppong out the exhaust pipes, and lossing 10 mile an hour.

 

I'm not really a mechanic, but it is my understanding that there can
be a lot of reasons for the popping. The largest concensus is that
your bike is probably runing a bit lean, I do believe.

The boots would make a difference, but keep in mind it can be a whole
bunch of different things.

In a proper exhaust system there should be some back-pressure through
the exhaust to the engine. Too little, or too much back pressure can
cause the valves to not open / close properly and that also can create
your popping sound, not to mention other various pre/post ignition
problems.

Some bikes, do it normaly, though I don't think yours is supposed to
and is probably indicitive of some other issue.