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1988 Yamaha Big Bear - No Spark/Won't Start

toolman0114

By toolman0114
in Yamaha ATV Forum

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toolman0114

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About 2 months ago I took drove my big bear from the garage and parked it in the shed, no problems. I started and ran great.

Today i tried to start it and it wouldn't fire. i pulled the plug and put it nxt to the cyinder and ther was no spark. I put a screwdriver in place of the plug, in case it was a bad plug, and same thing, nothing.

I checked the 30 amp fuse but no idea what to check next, or how to check it. I highly doubt it's the CDI box, or stator, I don't believe they would just die like that.

Any suggestions????

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  • 2 weeks later...
toolman0114 Explorer

toolman0114

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No I'm really confused.

I tore off the front plastics to check connections, still nothing.

Went out a couple days later to show a buddy who stopped by, and it started right up.

The next day I put the plastics back on but didn't have time to finish, it ran when I was done for the day.

The next day I finished putting it back together, and again it wouldn't start. I reached under the front plactics and giggled the wires and it started, I drove it around the yard and it died. I again giggled the wires and it started and ran, then it died and I haven't been able to get it running.

any suggestions? could it be a loose or broken wire, or could it still be the stator/pick-up.

:aargh::aargh::aargh::aargh::aargh::aargh:

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toolman0114 Explorer

toolman0114

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Check the kill switch and the wire going from the kill switch to the terminal board. because it kills the spark to shut down the engine.

I see the wires coming from the kill switch, it goes to a 3 prong plug, from there I can't find where it goes. where is the terminal board located? if i pull that wire off the terminal board will that elimanate the kill switch from the equation?

how about this:

from what my wiring diagram shows the kill switch has a black & a Black/white wire. the black goes to ground the B/W goes to the cdi unit. Am I correct to assume the kill switch grounds out the system much the same as a lawnmower grounds out the spark plug to stop it?

If I were to cut the B/W wire where it comes from the kill switch would that eliminate the kill switch? I could always solder it back together.

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toolman0114 Explorer

toolman0114

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I FOUND IT! I FOUND IT!!

I pulled the front plastics off again and started giggling the wires one harness at a time, what I found was when I shook the leads going to the key switch it fired, then died. I shook it again and it started, briefly. The bottom plate on the key switch is held onto the main part by 3 locking tabs, the plastic was so dry and brittle that one tab was missing, and the main body was cracked. I pushed it together and hot glued it in place and it starts/runs great. I ordered a new key switch. Thanx for all the help and advice.

This is by far the most helpfull board on the internet.

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