gas blowing out of intake...?

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15 Jun 2012 00:25 #529222 by battlecat
gas blowing out of intake...? was created by battlecat
i've got gas... coming out of my 1 air intake. backfires. lots of backfires. anyone....?
p.s. happens around 4000 and i have pods.

'79 Kz650b3 RAT. Used to ride an immaculate cb750. it was boring.

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15 Jun 2012 08:29 #529261 by Tomolu5
Replied by Tomolu5 on topic gas blowing out of intake...?
Did this just come out of no where, or has it been taken apart recently?

Mine:
04 Honda rebel 250(wifes)
04 GSXR 750(bolt on galore)
98 CBR 600F3(filter, pipe, adjustable cam sprokets, dyno tune)
76 KZ900A (LTD gauge pods, crash bars, LTD(style)pipes, dyna coils and ignition,headwork and mild port cleanup by cavanaugh racing, K&N filter pods, heck I dunno.

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15 Jun 2012 23:38 #529475 by Patton
Replied by Patton on topic gas blowing out of intake...?

battlecat wrote: i've got gas... coming out of my 1 air intake. backfires. lots of backfires. anyone....? p.s. happens around 4000 and i have pods.


Would check condition of the oil to determine whether gasoline has entered the crankcase.

Good Fortune! :)

1973 Z1
KZ900 LTD

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  • gd4now
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  • Denco where did you go?
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15 Jun 2012 23:52 #529484 by gd4now
Replied by gd4now on topic gas blowing out of intake...?
I would check the intake valve setting for that cylinder, it may not be closing fully. If you do you should check them all.

1977 KZ650 B1
Pods and Denco header


OLD KAW OWNERS SMILE ALOT

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16 Jun 2012 19:38 #529680 by battlecat
Replied by battlecat on topic gas blowing out of intake...?
it has been taken apart many many times recently.

'79 Kz650b3 RAT. Used to ride an immaculate cb750. it was boring.

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16 Jun 2012 22:00 #529701 by Tomolu5
Replied by Tomolu5 on topic gas blowing out of intake...?
Seems kinda like a valve lash/camshaft timming type issue, any chance your a tooth off?

Mine:
04 Honda rebel 250(wifes)
04 GSXR 750(bolt on galore)
98 CBR 600F3(filter, pipe, adjustable cam sprokets, dyno tune)
76 KZ900A (LTD gauge pods, crash bars, LTD(style)pipes, dyna coils and ignition,headwork and mild port cleanup by cavanaugh racing, K&N filter pods, heck I dunno.

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19 Jun 2012 21:46 #530404 by battlecat
Replied by battlecat on topic gas blowing out of intake...?
there is a very good chance that i am a tooth off. There is a very good chance that i am a little bit off everywhere. This bike has been parked behind the barn for a while....

and yes patton, the oil smells like gas...?

'79 Kz650b3 RAT. Used to ride an immaculate cb750. it was boring.

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19 Jun 2012 21:59 #530408 by Patton
Replied by Patton on topic gas blowing out of intake...?

battlecat wrote: ...the oil smells like gas...?


Regarding fuel intrusion into crankcase - - -

Say, for whatever reason, excess fuel is getting past the float valve.
Fuel level rises inside the float bowl.
Fuel reaches overflow level, where overflow circuit is supposed to allow fuel to escape before rising higher.

Say also, overflow circuit is clogged, for whatever reason (anywhere from tube entrance inside float bowl through exit from hose underneath bike), or carb doesn't have an overflow circuit.
Fuel level keeps rising, beyond overflow level, and on up into the carb throat.
This can happen with the bike parked or while riding. Thus, a perfectly functioning petcock is desirable, but isn't a panacea.

Fuel rising up into the carb throat flows both ways, back toward air box or pods, and forward toward the engine.
Fuel flowing back toward the air box or pods, can drip out of the pods or go into the air box.
Some air box designs allow an escape route for the incoming fuel.
Other air box designs permit the incoming fuel to flow through the crankcase breather tube into the crankcase. This is why some folks prefer to route a different crankcase breather hose to underneath the bike.

Fuel in the carb throat flowing forward toward the engine proceeds through the intake ports/valve into the combustion chamber, and flushes down around the piston into the crankcase.

Sometimes, fuel intrusion into the crankcase will be evidenced by an otherwise unexplained increase in the indicated oil level. For example, the sight glass may appear "full."

Would recommend changing both oil and filter.
And clearing the overflow circuits.
And correcting whatever condition is allowing excess gasoline to pass through the float valve, which is often crud or grit at the interface where the float needle fits into the seat orifice.

Good Fortune! :)

1973 Z1
KZ900 LTD

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