Fouled plugs

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Cteodorski
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Fouled plugs

Postby Cteodorski » Thu Apr 20, 2006 4:42 pm

Can someone describe the symptoms one would normally experience with fouled plugs?

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Vatch
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Postby Vatch » Fri Apr 21, 2006 9:34 am

As in how the bike would run, what the plugs would look like, or what was causing the plugs to be fouled?
'99 1500 Drifter

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DammitDan
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Postby DammitDan » Fri Apr 21, 2006 1:32 pm

What I've found is the bike will run "rough" with fouled plugs, as in the cylinders won't fire correctly. If a plug is completely oil fouled it could keep it from firing completely.

It's easy to check though. When you pull the plugs the outside bottom edge should ideally be a light tan color, and the center diode a dull silver-tannish.

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Cteodorski
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Postby Cteodorski » Sat Apr 22, 2006 11:22 am

My question was what behaviour does the bike exhibit when the plugs are fouled.

When I got my bike the original owner said you have to ride it with the choke open for several blocks for the bike to warm up sufficiently. My mechanic says "You never ride with the choke open".

Well, my bike seems to be having issues now and when I pull the plugs, it seems that they are always fouled and I'm trying to determine if my issues are because of fouled plugs. I'm trying to figure out if the previous owner or my mechanic is right....

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Vatch
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Postby Vatch » Sat Apr 22, 2006 4:22 pm

I always ride a few blocks, usually on half choke, but sometimes on full choke. Granted I'm no mechanic, but I don't understand how riding with the choke pulled out would do harm.
'99 1500 Drifter

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Ibsen
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Postby Ibsen » Sat Apr 22, 2006 5:09 pm

It is correct that you will need to run it with a little choke for the first 1/2~1 mile after you have started the engine from cold. But not with full choke. That will foul the plugs eventually. And when the plugs gets full of soot, the bike will run sluggish. What normally happens is that when the engine runs well without any choke, and is reaching full operating temperature, the plugs will clean them self. But if you only run short rides, and with the choke on, the plugs will collect more and more soot, and finally they will foul. The reason for fouling is that the soot, or more correct, the carbon that builds up on the plug tips will eventally act as an insulator, and prevent them from sparking.

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Volker_P
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Re: Fouled plugs

Postby Volker_P » Tue Apr 25, 2006 12:53 am

I think the CB 650 needs the choke quite long compared to other bikes, so do not worry too much about the mechanics statement. However he is right to claim you should not run with choke unnecessarily as this could cause fouled plugs as already said.
I would first make sure that the choke opens completely which means two things: First, the choke wire should have no load when pushed down completely. Second, the flaps should be horizontal. The flaps are connected to the choke lever only by weak springs which means that they do not need to be open just because the choke wire is down. The choke cam is divided into two parts for 1+2 and 3+4 so probably only one side would be affected in this case. Do all four plugs look the same? Other options could be a plugged air filter or wrong spark plug heat value. What about your ignition timing?

I would check these things, clean the plugs by a soft wire brush and go for a ride to get the engine really warm for at least 15 min or better more and check the plugs again. If you still have the same problems, maybe jetting is wrong or some carb parts may be worn.

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Vatch
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Postby Vatch » Tue Apr 25, 2006 8:32 am

Iginition timing or even firing sequence. The wires to the plugs went to the wrong cylinders on my bike when I bought it. Fixing that certainly helped.
'99 1500 Drifter

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Volker_P
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Re: Fouled plugs

Postby Volker_P » Tue Apr 25, 2006 8:52 am

Firing sequence? Hmm, 1+4 and 2+3 ignite simultaneously (circuit in series) so mixing up these would have no effect. If you mix up e.g. 3 and 4 (as I managed again after my second camshaft exchange), it is running only on two and two exhaust pipes will stay cold. This time I recognized it quite early but I remember some years ago I blew a hole in my old exhaust with the explosion into the open valve. :? I would guess the symptoms do not fit to bad firing sequence.


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