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Gas dripping out of airbox on KZ1100
- KYKZ1100
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1981 KZ1100A1 Shaft
2007 BMW R1200R
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- Patton
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Fuel reaching the airbox may drain down through the crankcase vent hose into the crankcase and contaminate the oil. (See image below).
Fuel flowing forward may go through the intake port and enter the combustion chamber where it flushes down past the piston and rings into the crankcase.
Would sniff-test the oil and examine its physical condition to help determine whether fuel contaminated oil might be an issue. It's bad enough in some cases to cause an increase in the apparent oil level.
Where there's fuel intrusion into the crankcase, it's best imo to change the oil and filter, and correct the problem before allowing any fuel to reach the carbs.
Good Luck!
[Click on image to enhance view.]
1973 Z1
KZ900 LTD
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- TeK9iNe
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- What did you do!?!
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If not, I would seriously recomend doing so...
Good luck!
Motorcycle Shop Owner/Operator
79 Kawie Z1000 LTD
81 Kawie Z1000 CSR
83 Honda VT750C A
85 Kawie GPZ900 A2
86 Zukie GS1150 EG
93 Yamie XV1100 E
Lucky to have rolled many old bikes through my doors
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- KYKZ1100
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Is a bad float valve the only way gas could get into the air box or cylinder when the engine isn't running?
I can't remember if the rebuilding kits had both the float valve and the seat or just the valve. Whichever it had I replaced.
1981 KZ1100A1 Shaft
2007 BMW R1200R
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- Patton
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...Is a bad float valve the only way gas could get into the air box or cylinder when the engine isn't running?....
If the float itself is leaking or sticking or maladjusted or broken or has lost buoyancy for whatever reason (such as becoming "water-logged"), it can fail to push the float needle into its seat, whereby the valve remains open.
Good Luck!
1973 Z1
KZ900 LTD
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- KYKZ1100
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1981 KZ1100A1 Shaft
2007 BMW R1200R
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- Patton
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Thanks. I've had a problem with exhaust popping since I got the bike. I'm going to take the carbs off to install larger pilot jets to see if I can fix that so I'll check the floats when I do that. They looked good last time I had the carbs apart.
Hoping the clear tube test has been done to assure correct service float bowl fuel level.
In otherwise perfect carbs, too low fuel level could cause lean condition (with exhaust popping), and too high could cause rich condition.
Sometimes, slightly enriching the pilot circuit via the adjustment screws will reduce or eliminate the popping.
Any doubt as to integrity of the carb holders or attachment of carbs (such as a loose clamp)? As an air leak could cause popping.
Good Luck!
1973 Z1
KZ900 LTD
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- KYKZ1100
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1981 KZ1100A1 Shaft
2007 BMW R1200R
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- Grantl
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You should look at the petcock as well as the float valves.
Best of luck,
Grant.
1981 KZ1000 CSR
1983 KZ750 Project Bike
1990 550 Zephyr
1994 KZ1000 P
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- KYKZ1100
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Sounds like your petcock is not shutting off the flow of gas when the bike is turned off. I'm assuming your bike has a vacuum actuated petcock. If this is the case, the flow of gas is overcoming the sealing ability of your float valves and once the level exceeds the travel of the floats, the gas overflows into your airbox--and possibly down into your crankcase via the crankcase vent hose.
You should look at the petcock as well as the float valves.
Best of luck,
Grant.
It makes sense that both the petcock and at least one float valve would have to be bad in order for gas to be leaking when the engine is off. I'll add rebuilding the petcock to my list.
1981 KZ1100A1 Shaft
2007 BMW R1200R
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- greek023
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Jim
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- hocbj23
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