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CB500/550 / Cb500 fouling plugs once warmed up.
« on: March 30, 2014, 12:35:28 AM »
Hello
I'll describe my bike setup before the problem.
1972 cb500 (german/ netherland spec.)
649a carburetors
78 main jets
40 slow jets
1.125 turns out air screw
22mm float height (checked with tool and also a clear tube)
original air duct installed
Uni foam air filter (light dusted with K&N air filter oil)
Jardine 4-1 exhaust
d7ea ngk plugs gaped to 0.65mm
The bike starts up well with a little choke (3 degrees celsius today), slowly turn off the choke as it responds. I start riding the bike and when the bike is finally up to operating temperature (2-3 miles) the bike starts back firing/ miss firing and stalls out. Pull the plugs and I get 4 black plugs that are wet with fuel.
I believe the problem is a weak spark, because no matter what I do to the bike on the carb/intake end has any effect. I've had the filter on and off and the results are the same. The main jet set at 100 and the stock 78, no effect. Air screw adjustment does affect off idle performance, thats about it.
Any or all thoughts would be appreciated.
I'll describe my bike setup before the problem.
1972 cb500 (german/ netherland spec.)
649a carburetors
78 main jets
40 slow jets
1.125 turns out air screw
22mm float height (checked with tool and also a clear tube)
original air duct installed
Uni foam air filter (light dusted with K&N air filter oil)
Jardine 4-1 exhaust
d7ea ngk plugs gaped to 0.65mm
The bike starts up well with a little choke (3 degrees celsius today), slowly turn off the choke as it responds. I start riding the bike and when the bike is finally up to operating temperature (2-3 miles) the bike starts back firing/ miss firing and stalls out. Pull the plugs and I get 4 black plugs that are wet with fuel.
I believe the problem is a weak spark, because no matter what I do to the bike on the carb/intake end has any effect. I've had the filter on and off and the results are the same. The main jet set at 100 and the stock 78, no effect. Air screw adjustment does affect off idle performance, thats about it.
Any or all thoughts would be appreciated.