weak spark on 3.5 tec.

#1
I'm refurbing a 3.5 Tec for my Manco Chopper project and can't get the spark as strong as I would like. This is an old edger engine, points/magneto ignition system with an iron flywheel.

All has been checked and rechecked, everything (coil, points, wires. condenser, flywheel has been changed, changed back and changed again... nothing seems to make any difference. Just a damn weak spark when spinning it over by hand.:shrug:

I've got another (blown) engine with a similar ignition system with an aluminum flywheel that generates a much better spark every time. (No, the aluminum flywheel won't fit 'cause of the different crankshaft size/taper)
Besides, the iron flywheel should, in theory, generate a much stronger magnetic field.

I'm wondering if it's really normal and I just can't spin it fast enough by hand to really get it to light up. I'm to the point of assembling the damn thing and just trying it with the pull starter and see what happens.

Any thoughts or suggestions would be seriously appreciated.

mardyn
 
#2
well given the the other fly wheel gives you better spark , i would say you possibly have weak magnets . put it together and pull the rope . if it starts good if not you may need a magnet recharge or a different flywheel
 
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#3
Tried a different (iron) flywheel this morning... same song, second verse-no change in spark or intensity.

I changed the complete magneto module, cleaned all the contact grounds, have tried two flywheels, repositioned the timing and air gaps.. nothing seems to make a difference.

It's quite frustrating.

mardyn
 

TomH

New Member
#4
Tried a different (iron) flywheel this morning... same song, second verse-no change in spark or intensity.

I changed the complete magneto module, cleaned all the contact grounds, have tried two flywheels, repositioned the timing and air gaps.. nothing seems to make a difference.

It's quite frustrating.

mardyn
I feel your pain. Going with an ignition module next myself. TomH
 
#5
is the other motor newer then the one your working on? is it possible that you are looking at the best spark that the iron motors will make you have . and trying to compare it too a much better coil ? say the blowen motor has a better spark then the good(iron flywheeled ) motor could ever have ?
 
#7
Reassembled the engine.... pulled it through with the recoil starter, spark now seems more significant than spinning by hand.



I'll put some fuel & oil in it soon and see if it'll run.

mardyn
 
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