Hello!
I was trying to repair my Yamaha GT80 for 2 months now. I got compression tested, new spark plugs, new carburetor and I was ready to fire it up, but have found that I have no spark. I used to have spark before on that engine and it was good, but yesterday, when I tried to start it, there was none. I checked voltage with my multimeter across ground and spark plug cap and got more than 600 volts for sure. But when I plug spark plug it gives spark very rare, I would say almost no spark. What could be the problem? I cleaned ground spot on coil, checked for resistance and it was in range. Only thing that wasn't right, as I think, is that there is no resistance across ground and plug cap. Can it be the problem?
Thanks in advance!

Page 63 of service manual has useful info for specs on points gap/coil/condenser.

Consider verifying plug is not cracked, points are opening/closing/making contact.

You just wrecked the meter.

Plug has electrolyte on the porcelain.

cliff

Meter is still working, nothing bad with it. What did you mean when saying plug has electrolyte on the porcelain? Did you mean spark plug? and how could it be a problem? Thanks

Sometimes a residue is one the center porc. and is conductive enough to waste the spark inside of the cavity.

No spark on tips of center and ground strap.

Mostly carbon. Sometimes silica from sand blasting. A few with acid cleaning.


cliff

Now I get it. Thanks. I tried 4 different ignition coils and one of them worked, so I guess that was a problem. I also connected it directly to spark without plug cap. I started it with starter fluid and it worked for a couple seconds.  Only left is to fit it back on bike. Anyways, thank you for help