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Big Al

1987 Yamaha Big Bear How To Test CDI

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Hi, I’ve also found bad connections in the spark plug housing. Reach in there with a slot head screw driver and unscrew it and check it out. 

Just sayin’ 

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On 9/5/2018 at 3:56 PM, bryanta0502 said:


If someone could find the link to this i would like to check it out. Sounds very interesting.

Any update on this? I'd be interested too.

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Wow. Everyone is all over the place on this. 

Great looking bike awesome find lucky you! 

The cdi is a working or non working component.  So the fact that it fires up I would say it’s good.  

Now since you have all the plastics off and everything is exposed I would take your time and unplug each plug one at a time and clean and add electrical lube and reconnect. 

A good eye glass screwdriver allows you to get in and scrape clean the contacts of all the plugs.

after that go through all the wires that are attached with a bolt or screw, grounds, battery connectors and the starter relay .  It’s very possbale that the starter relay is no good and a much cheaper part to replace. Keep in mind the electrical system is big! That means the coil wires, ignition, handlebar controls, regulator etc. do it in sections and move on to the next section.

After all this is done if it still does the same thing it hasn’t cost a penny before you start guessing and buying parts and all bad connections are ruled out. 

Put a fresh battery in that baby and see what you got.

Lastly is I’ve had a bad cdi box and one way that it will not perform is if it has moisture inside. Simple stupid way to get that out is to put it in the oven for 10 min on 250! Make sure the oven is on 250 before you put it in and no more then 10 min. Take it out and cool off and try it. 

Good luck and keep up posted.

 

 

 

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