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Past Due
04-25-2019, 01:24 PM
Hello all,
I've been hanging around this site for a year. I have never been much of a joiner, very much a loner but figured it was time to get involved if I wanted to ask questions. You folks seem like a great bunch. The patience that has been extended with some of the silly questions is incredible! Hopefully I can be the recipient of some of that patience.
I have an '85 Honda ATC 200S that I have put WAY too much money into restoring it. Powder coated everything, new plastic, new tires, new seat, new bearings, fresh cylinder, new to me cylinder head and valve work. I have always been able to fix things or figure them out but this one has the best of me. After assembly and checking my handywork I rotated the engine checking for spark. The spark is very weak, barely visible in a lighted garage. I started on diagnostics: cleaned every connection on the wire harness with contact cleaner and small wire brushes then checked for continuity at all connections. Checked specific ohms readings at every pin on the CDI unit verifying readings to the Honda service manual. New coil and wire even though the old coil's resistance checked out via the service manual (primary and secondary sides). Checked the resistance at the pulse generator... within service manual spec. Removed the handlebar kill switch so that it was not part of the equation. Added an auxiliary ground from the frame to the engine (bad grounds can cause you to pull your hair out!) Verified proper continuity at the exciter coil, resistance was 200 ohms. Every harness and frame connection was installed with dielectric grease. Replaced the original rotor with a known good unit (not sure that the old had lost any magnetism??) And yes, a new spark plug.

After all of that, I have the same very weak spark. What the heck am I missing? Thanks for your helps!

PD

350for350
04-25-2019, 08:49 PM
Two things come to mind. First, have you checked the air gap on the pulsar that's on the end of the cam? Too big of a gap or even some dirt on the magnet could lead to a weak spark. Second, have you tried to actually start it? Sometimes the spark will look weak while you're cranking it over, but will still be good enough to burn the fuel in your cylinder.

shortline10
04-25-2019, 08:59 PM
Try checking the spark in the dark , if it shows a blue spark it’s good enough , these machines are known for having a weak looking spark .

Past Due
04-26-2019, 11:09 AM
Two things come to mind. First, have you checked the air gap on the pulsar that's on the end of the cam? Too big of a gap or even some dirt on the magnet could lead to a weak spark. Second, have you tried to actually start it? Sometimes the spark will look weak while you're cranking it over, but will still be good enough to burn the fuel in your cylinder.

Thanks for the reply! I have checked the gap, but it would be worthy to double check it. No, I have not tried to start it, I was trying to make sure everything was "set" before I started tugging on the beast. If that is just the way a spark looks on this thing but it runs fine I'm going to throw something!
Thanks again.

Past Due
04-26-2019, 11:13 AM
Try checking the spark in the dark , if it shows a blue spark it’s good enough , these machines are known for having a weak looking spark .

I'm going to do that tonight. I'll report back. Thanks for the input. I think my Clymer manual said something about a "fat" blue spark. If what I have for a spark is fat, then I'm going to start Sumo Wrestling.
Cheers!

shortline10
04-26-2019, 12:18 PM
Definitely not a fat blue spark and very hard to see any spark under light .
I usually pull the recoil and spark plug and run a drill on the 17mm flywheel nut to check for spark on these motors .


I'm going to do that tonight. I'll report back. Thanks for the input. I think my Clymer manual said something about a "fat" blue spark. If what I have for a spark is fat, then I'm going to start Sumo Wrestling.
Cheers!