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Discussion Starter · #1 ·
Just a question for you guys. I'm looking to start doing all of my bike repairs myself and with still not being familiar with the location of everything on bikes, I'm just wondering. I know the spark plugs are in the cylinder heads, but do you have to take the top of the heads off to get to them? Or do you just pull out the black cable running into the head and have access to the spark plug that way? Just for reference, I've got a '79 CX500 Custom.
 

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Welcome to the forum. Don't be shy about asking even simple questions. Likely as not, there are other folks wondering the same thing.



Just pull the wires out of the valve covers, and using a 18mm socket with an extension insert into the plug well. Your bike's tool kit may also have a plug wrench in it. When the plug is completely loose, just poke the wire back on top of the plug and push down a bit. Then you should be able to pull the plug out of the well with the wire. There are some dedicated plug sockets that use a foam insert to grasp the plug and you can withdraw the plug with the socket.



Inserting is just the opposite, but get the threads on the plug started with your fingers before you put a wrench on the extension. It is easy to crossthread if you use a wrench to start. With your fingers, it is almost impossible to crossthread.
 

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Discussion Starter · #3 ·
Thanks for the clarification. I'm going to pick up a set tomorrow and throw em in. I hope this'll help improve my gas mileage and make the bike start easier.
 

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Before you pull the plugs, be sure there is no debris in the plug well. A good shot of compressed air should clean it out.



A factory service manual is a good thing to have and read.
 

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Don't forget to gap the plugs too! If possible, take a picture of the old plugs and post on this forum. It's pretty easy to tell if your mixture is on or off by looking at the plugs. They should be a light tan colour. Mixture is all part of gaining better mileage as well as ensuring your combustion is at maximum.
 

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Discussion Starter · #7 ·
Good call on the compressed air. I have an 18mm plug socket that I'll be using tonight, if that doesn't work, then I have another one for my mower that should do the trick. The plugs I have are pre-gapped, so that shouldn't be an issue. I'll check the condition of the plugs and I do think it is running on the rich side. I should be getting another 5-8 mpg, seeing as how I got about 44 on my last fill-up and I dont ride the bike very hard, its not cold, and I do a lot of highway riding. Any MN riders out there who'd be able to help me adjust my mixture screw if needed?
 

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Not sure about the CX500 tool kit (or if the bike you have still has it) but the tool kit in my GL500 has a proper plug socket. Proper in that it has the rubber "bushing" (not sure what else to call it??) that protects the porcelain of the plug, and it grips the plug securely so that it can be pulled out easily.



If you are in a bind a thin walled 3/4" socket will work but it is best to have the proper sized one.



Not sure of your experience wrenching, but be sure not to over torque the plug into the aluminum head. As a farm kid I did plenty of mechanical work but all on heavy, crude, cast-iron implements, when I got into bikes, I had to learn to apply a little more finesse and less raw muscle.







I paid the little extra and went with Iridium plugs, don't know if I will recoup the cost in fuel economy but I like to pamper my ride.
 

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Discussion Starter · #9 ·
Yah, I read on another thread that you want to tighten them a half turn past hand tight. Thats all I'm probably going to go.
 
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