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Dave-Saratoga

magneto?

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Dave-Saratoga

while doing repairs on BGB as discussed in a previous thread, I had set the cowl yp on to of the gas tank/battery. While standing up one time - i accidentally knock the cowl in contact with the positive terminal of the battery.

This caused some smoking and heating of wires. However - i immediately pulled the cowl away from the terminal - turned on the ignition key and the engine started right up.

So I continued repairs to the bgb, reassembled rear end and thought I was done. ha!! when i went to start the engine, the generator turned as normal but there was no spark. Inspecting some of the wires coming from inside the cowl I did notice that some had melted. So I undid the wire to the keyed ignition undid all the wire connected to the generator (mostly from the voltage regulator) and engaged the generator with a jumper cable. Still no spark

I'm thinking I'm looking at having to pull the engine and replace the magneto. it an electronic magneto so no points or condensor.

any input guys? XX(

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PhanDad

I think somewhere the insulation is gone from the kill wire - anywhere along the path from the ignition switch to points cover to under the tin to the mag. If it's touching ground, no spark.

If you're lucky, it'll be outside of the engine tin.

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BLT

First guess for now is your mag wire insulation has an open spot and grounded somewhere . There should be two wires on an insulated board on the points box cover. On goes to mag, the other to key switch. Disconnect and separate both, then try to start engine. If it runs, my guess is you have a problem with other wire. You can stop engine by grounding the wire that disappears into blower housing.

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Dave-Saratoga

BLT - did that.

cranked the generator off my jeep battery. deadman wire was loose and disconnected from ignition key switch and just dangling. wire to plug from magneto seem flexible and not fried.

i took it down to a simple circuit

i should have had spark from magneto by just turning the flywheel with the generator. NO? i thought so. no spark. brand new plug

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PhanDad

If any of the dangling wire, including the part that goes under the housing tin is touching ground there is no spark. So if it not touching external, then it could be touching under tin. Check that wire for continuity to ground. If it shows continuity, the tin has to come off.

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Dave-Saratoga

continuity check

wire coming from key switch - one end on wire one end to frame

key off - 0 ohms

key on 20 ohms

deadman wire coming from magneto

20 ohms

spark plug wire from magneto - 20 ohms

reconnected wires from key switch to magneto

20 ohms either on and off

magneto and/or wires grounding out

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dentwizz

If it is an electronic mag(not points) the transistor set can be killed by a battery source. The windings are not all that thick or capable of handling current. The good news is they are not that expensive other than the work to take it out of the engine.

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Dave-Saratoga

hahahha yeah great.

6 hrs of pulling the engine later -........

lol

all that after rebuilding the bgb

ah, ya gotta love these old machines

ok sarcasm works sometimes

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Dave-Saratoga

guess it depends on supply in beer fridge lol

i just bought a 90 degree air wrench at harbor freight. it took 5 mins to do that this morning. used to take hours - or so it seemed - with a socket set

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timflury

Is this a Magnetron coil???

The Magnetron requires 300rpm minimum for it to make a spark.

Not only that, is the engine pre 1981 vintage???

Was the flywheel sent to Briggs to have it repolarized??

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