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Author Topic: cb500/4 plugs problem  (Read 1157 times)

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Offline emilios

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cb500/4 plugs problem
« on: May 11, 2009, 04:12:29 AM »
Hi
I have just finished my cb500/4 1972 and run for about 120 miles..
Yesterday i had problem with starting and then i found that number 2 and 3 plugs were dead.
I changed them and now runs great,like before.
My question is do i have to worry for something or check something??
I had problem with the old one coil and i put new one for cylinder 2 and 3...
Points are new..
I bought coil from a company in London and they said that can fit only to cb500/4 and some other bikes but i dont remember..
Any idea?
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Offline Lars

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Re: cb500/4 plugs problem
« Reply #1 on: May 11, 2009, 05:37:56 AM »
Not an expert on coils, but what did the two 2-3 spark plugs look like when you got them out? Any indication on running lean or rich? Since both went dead, I would assume this has to do with your new coil, lets see what the experienced guys says. I am curious, as I am into coils at the moment, too.
Lars
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Offline bryanj

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Re: cb500/4 plugs problem
« Reply #2 on: May 11, 2009, 08:04:17 AM »
What plugs you using
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Offline emilios

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Re: cb500/4 plugs problem
« Reply #3 on: May 11, 2009, 10:59:17 AM »
Quote from: Lars on May 11, 2009, 05:37:56 AM
Not an expert on coils, but what did the two 2-3 spark plugs look like when you got them out? Any indication on running lean or rich? Since both went dead, I would assume this has to do with your new coil, lets see what the experienced guys says. I am curious, as I am into coils at the moment, too.
Lars
plugs look dark
and plugs where D8EA
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Offline hymodyne

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Re: cb500/4 plugs problem
« Reply #4 on: May 11, 2009, 11:02:30 AM »
coil issues perhaps. check for spark from each plug with a spare attached to the boot
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Offline emilios

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Re: cb500/4 plugs problem
« Reply #5 on: May 11, 2009, 11:32:59 AM »
Quote from: hymodyne on May 11, 2009, 11:02:30 AM
coil issues perhaps. check for spark from each plug with a spare attached to the boot
but i did that and spare plugs spark ok...so i changed plugs and bike run in 4 cylinder again...
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Offline TwoTired

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Re: cb500/4 plugs problem
« Reply #6 on: May 11, 2009, 11:37:33 AM »
The stock plugs for that motor are D7EA, which is a hotter plug.  Not sure it will cure the plug fouling issue though.

Might have to go through the carbs and note settings and jet sizes.  Clean status, and air screw settings, etc.

Old air filters can make plugs soot up, too.  But, I expect you already addressed that.
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline emilios

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Re: cb500/4 plugs problem
« Reply #7 on: May 11, 2009, 11:52:02 AM »
Quote from: TwoTired on May 11, 2009, 11:37:33 AM
The stock plugs for that motor are D7EA, which is a hotter plug.  Not sure it will cure the plug fouling issue though.

Might have to go through the carbs and note settings and jet sizes.  Clean status, and air screw settings, etc.

Old air filters can make plugs soot up, too.  But, I expect you already addressed that.
Carbs have new stock jet sizes(100 main,40 slow)new stock air filter..as for air screws i never understand how to set them rigth...i know that manual say 1 1/2 turn out but only that.
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Offline TwoTired

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Re: cb500/4 plugs problem
« Reply #8 on: May 11, 2009, 12:42:01 PM »
If the air filter and exhaust is stock, the stock air screw setting is fine.

The main and slow jet are only two of the carb's settings/metering devices.  Check the FAQ for a chart listing others. But, the main needle size, taper, and clip position is pretty important, too.  There is also "clean" to consider, especially for the emulsion tubes.

Cheers,
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline Lars

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Re: cb500/4 plugs problem
« Reply #9 on: May 12, 2009, 06:25:57 AM »
I recently got a CB 550 I cleaned up for sale. It had a 4-1 muffler on which I replaced with the original 4-4. The carb needles had been set to a higher posistion with the 4-1 on, and with the 4-4 on the engine ran too rich and plugs turned black. Checked the needles and reset the circlip to the middle position, and everything was OK.
However, I still think you might have an issue with your 2-3 point or the timing, coil....
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Offline emilios

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Re: cb500/4 plugs problem
« Reply #10 on: May 14, 2009, 11:18:44 AM »
I finally check totay the 2-3 point and i found that was more close that it should be..
I hope that this is the problem...i set the point at 0.30 mm
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