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Outside rich inside lean! Help
- jmoney05
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What could cause this? Any input is welcome,
1978 Kz650D
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- 4TheKZ1000
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could be a bad rubber intake boot. They can dry out, rot and crack letting air in creating a lean condition.
Lean is caused by two methods.
1. to much air to fuel. Proper fuel flow / to much air.
2. not enough fuel. Proper air flow / restriction of fuel / not enough fuel.
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- kaw-a-holic
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Jon
1977 KZ1000a1
Mesa, AZ
Phoenix Fighter Project
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- Patton
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jmoney05 wrote: The two outer cylinders and very rich while the inner two are fine. VM26 s on a 1978 kz 650 D
What could cause this? Any input is welcome,
If not already done, would assure correct fuel levels by performing the clear tube test.
Incorrect fuel level can result in too lean or too rich mixture in an otherwise perfect carb.
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1973 Z1
KZ900 LTD
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- jmoney05
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The bike was running so rich that my oil was getting contaminated and all four plugs were solid black. So I changed the oil and put new plugs.
I had the carbs off and changed the jets ( they were all the same ) from 117.5 I jetted down to 115 and also put new needle and seats, and now is my current situation with the outside cylinders plugs reading solid black.
The bike runs a lot better since re-jetting but is still way off.
1978 Kz650D
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- jmoney05
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1978 Kz650D
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- Patton
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Often results from a leaking float valve, accompanied by an imperfectly functioning overflow circuit.jmoney05 wrote: ... bike was running so rich that my oil was getting contaminated ....
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1973 Z1
KZ900 LTD
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- martin_csr
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Are they oily black or sooty black?jmoney05 wrote: The bike does have pods, I'm sure there is no vac leaks. The inside plugs look decent the outside plugs are solid black.
The bike was running so rich that my oil was getting contaminated and all four plugs were solid black. So I changed the oil and put new plugs.
I had the carbs off and changed the jets ( they were all the same ) from 117.5 I jetted down to 115 and also put new needle and seats, and now is my current situation with the outside cylinders plugs reading solid black.
The bike runs a lot better since re-jetting but is still way off.
What ignition system is on the bike & does it have the stock coils?
I'm thinking it might be poor spark, possibly from a bad 1-4 coil.
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- Patton
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While there might also be an ignition issue, gasoline intrusion into the crankcase likely resulted from a carb problem.
The scenario is that raw gasoline rises up into the carb bore and is sucked into the combustion chamber, from where it then blows out the exhaust and/or washes down around the pistons and rings into the crankcase. Under such condition -- basically flooded -- , the cylinder likely fails to combust. And the spark plug gets dripping wet with raw gasoline.
Hopefully, the new float valves have remedied the issue of gasoline intrusion into the crankcase.
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1973 Z1
KZ900 LTD
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- Patton
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In any event, would also assure that the overflow circuits are clean and clear. Because a new perfectly functioning float valve may later start leaking (for whatever reason), and when that happens, the overflow circuit needs to be working.
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1973 Z1
KZ900 LTD
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- jmoney05
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1978 Kz650D
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