Magnet scrapes against coil

Fletch

New Member
Aug 8, 2018
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Hey guys, I finally joined so I can talk to you about the issues I'm having with this motor. Since getting it running again, I have no torque at all. On straights it runs good, but as soon as I hit even the slightest incline at all, it bogs down to nothing. So, I've been going over the motor looking for issues.
One issue I found is that the spinning magnet which should never actually touch the magneto coil is grinding on the bottom leg of the coil, and the top leg has a pretty wide gap where it should be closer. It runs like this, but I can hear a sneak from it rubbing. I grinded down one magneto coil I had to stop the rubbing, but that still leaves huge gaps between the magnet and coil and looks ugly. I have tried different coils and magnets and have determined none of those are out of shape. It is either the holes weren't drilled properly making the coil sit too high and rubbing the magnet, or I'm wondering if the crank is bent. If I am not mistaken the magnet attaches to the crank? I've never taken the crank apart and wouldn't know what to do if this was the problem. Anyone experience anything like this? I can give more details later. Thanks
 

crassius

Well-Known Member
Sep 30, 2012
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USA
there is a raised, circular boss cast into cases - as the screws for the stator are just getting tight, wiggle it a bit to get it to sit squarely on that boss - this will give you proper clearance all around
 

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
6,608
416
83
Los Angeles, CA.
Normally, you would simply use a small flat-head screwdriver to pry the magneto over to adjust the gap (then tighten the screws)... You might consider just buying a new magneto & starting fresh at this point.

As far as your up hill power issue... have you done anything to the engine recently that might help us track down the problem??
 

Fletch

New Member
Aug 8, 2018
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I was using the phone earlier and am now at a computer, able to sit down and get into more details. I tried replacing the magneto coil and the magnet with ones from another motor, and they both continue to grind, so I can say it is neither of those at fault. I tried using a flathead screwdriver to try to pry it in the correct position, but it was more than just a bit off, where you might use the flathead to do fine adjustments. I vrealized that the screw hole for the crankcase cover right below the magneto coil was pressed tightly against the magneto coil, and grinded down some spare material off of it without getting too close to the screw hole, and was actually able to get the magneto on quite a bit closer. There is still a slight rub, and a bit of squeaking from it, but it is much better. I will try to keep working at getting my magneto centered.

As far as other modifications, it's kind of a long story.. This bike has been sitting outside for the last 2 years while I have been incarcerated, and I was having issues with it before I was incarcerated. If I recall correctly, this thing was burning through magneto coils, and I had assumed it was the stock CDI and went with an aftermarket CDI. This would've been shortly before my incarceration. I recall having this thing running and being able to crank right up any hill without a problem. I know at some point I had went from a 44 tooth to a 40 tooth sprocket to go faster, but I believe I was still able to climb hills with it like that. My memories a bit shot. So anyway, when I got out, I wanted to fix it. I tore it all apart and cleaned up everything while I waited for parts to come. I replaced many parts at once, but none of them too major.

I replaced my CDI, went from bikeberry's $20 one to the $30 one with the on/off key switch, but I assume the keyswitch to be the only difference.
Replaced the clutch pads
Added an air filter (didnt have one)
Went from the stock intake to the shorter cylinder matched one
Been experimenting with different cylinder heads and head gaskets from my graveyard
A bunch of other minor thihngs completely irrelevent to this issue...

I was thinking I was getting a bad spark, or maybe a bad seal in my head gasket, but now I have no idea... It runs great at higher RPMs. If I am on a nice straight away, especially if right after going down a hill, I will crank right along at 30 MPH and I can feel the powerband in it. But I hit even the slightest elevation and I immediately lose all power and have to pedal up the hill while holding the throttle all the way in, just to keep the engine barely puttering enough to not stall out on me. I'm tempted to just order a larger sprocket so I can hit the power band at a lower speed but I really feel like that's more of a band-aid than a solution. The motor should have a lot more torque than I'm getting right now. I'm only 140 pounds. I'm getting desperate here, I'm running out of ideas.

I had a video of my bike on youtube a few years ago...it's a bit different now, but it gives you the idea, so here you go

I did replace the carb, and the CDI as mentioned before, and I have not been using the same head as on this video
 

Tyler6357

Well-Known Member
Mar 15, 2012
1,120
163
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Santa Barbara, CA
Maybe when it gets on an incline it's not getting enough gas. You should try it without that bottle booster thing. Maybe it has an air leak when you to uphill and put a big load on it.
 

crassius

Well-Known Member
Sep 30, 2012
4,032
155
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USA
often times when the rotor hits stator and can not be aligned properly, it is because the main bearing on that side of crank is bad - try prying with your screwdriver under the crank to see if it moves up and down a bit
 

Fletch

New Member
Aug 8, 2018
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Thank you for your reply, I will try this tomorrow. I hope I do not have a bad bearing. I have 2 old motors laying around I tried splitting open, just to practice on so I would know what I'm doing when I'm working on a good motor, and I couldn't get either one of them apart for the life of me...i imagine if I need new bearings, I'll need a new motor..
 

crassius

Well-Known Member
Sep 30, 2012
4,032
155
63
USA
many people find a new motor is cheap enough to avoid the hassle of fixing an old motor plus the expense of the repair parts