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diagnosis before I buy??

1139 Views 8 Replies 4 Participants Last post by  dezz
Hey guys, glad to have found this forum and look forward to engaging with y'all.
I need some help though , just recently decided to get me a bike and start riding again. However I need some help.

Going to look at a 2012 Grizzly 300 tomorrow, gentleman that has it is 70years old and said he bought it new to use on farm, he says it is in very good shape and all factory condition. He told me that it keeps " blowing ignition modules" says he had a friend replace it , rode a few weeks then it happend again to him..I think he has a good price on it .. $800 obo so I would like to pick it up if it is as he says it is.. any known issues with these bikes on this issue? Any way I can bypass so I can at least hear the motor run? I have a background in industrial maintenance, but no wiring diagram. I don't mind fixing shorted wires, connections etc, but I don' want to be buying stators, cdi's etc.. any help will be much appreciated
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Welcome to GC. We have some members who are good with electrical. They should be able to give you some guidance.
Sounds to me there is either a chafe in the wiring harness causing a short, or possibly the voltage regulator has failed and is putting out too much voltage, frying the module.

I would also like to know what he is calling the ignition module. Is it the CDI he means?
Thanks for the response guys,
Yes I agree sounds like something is contacting where it shouldnt. I was also curious about the "ignition module". He did mention that he bought a replacement on Ebay for $70 new if that gives you guys any clues , I'm curious myself... guess I will take a meter with me this afternoon and see what I can find out . Is there a schematic somewhere that I can find out what the components should read with a meter on them?

Thanks again
You can get the Yamaha Service Manual through tradebit, costs $14.95 as a download.

Yamaha Grizzly 300 service manual repair 2012-2013 YFM30G
Got to take a look for a few minutes today. It was the CDI box that has went out twice on him. He replaced it and rode for a few months , then it went out again. I couldn't see any breaks in the wiring without stripping the wiring bundle.. he did mention that the battery spilled over sometime in this cdi problem. Cdi box was bulged. I'm wondering if the battery acid got to the wiring .. any ideas guys? Already talked him down to $600 . Want to go look again tomorrow as we ran out of daylight today.. thanks for the help
I don't have any helpful info for you other than it may take some time digging through the wiring to find the problem. But at $600, I think I'd be willing to take a chance on that bike if that is the only known issue and the rest of the bike looks good.
I don't have any helpful info for you other than it may take some time digging through the wiring to find the problem. But at $600, I think I'd be willing to take a chance on that bike if that is the only known issue and the rest of the bike looks good.
Agreed. You could probably part it out and get your money back if you had to.
The battery boiling over and a fried CDI is indications of a high voltage....more than likely caused by a failed voltage regulator.
Start by inspecting the harness. If there is no problems found, replace the CDI to get it running then check charging voltage at the battery...especially mid-range RPM's. If higher than 14.4 volts, voltage regulator is toast.
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