I've had this bike for years, tinkered on and off with it, but never really dug into it until recently. For the longest time, it would just not start, not even a puff with starting fluid. And that was with 125psi compression and good spark. Tracked down my woes to bad crank seals, swapped those out, (re)cleaned out the pilot jet, primed the oil pump, and cleaned the points and finally got it running the other week! It's fairly low miles (2880km or 1790mi. It's a JDM bike.) and always been in either a shed or garage so internals and all that are fairly clean. Put about 70mi on it riding around (and learning to ride, it's my first bike) before running into trouble the other day.

I had just bumped up the pilot jet one size and had the bike idling to test, it was a big improvement on throttle response from idle, definetly what the bike wanted. Anyway, I was making the last few adjustments and trying to get the brake light switch working correctly when the engine make an awful screech noise and seized. Couldn't even kick it over with the kick starter after it cooled. I didn't think it had overheated, it wasn't even that hot to the touch, must have seized the piston cause the oil pump died (it had good flow out the bleed screw, but no pumping action with the throttle held wide open and turning the pump by hand).

I pull the head off, all looks ok, gently tap the piston with a brass rod and a 't the piston. There's a tiny gall spot and some scoring down below the ports, but nothing that looks too bad. Used some fine sand paper to remove the aluminum from the bottom of the cylinder and stoned the high spots on the piston per the manual, rings look a bit wonkey in that spot, but who knows if that's new or old? Engine is still locked up hard though, must be crank bearings. So I pull the engine out of the bike and start tearing it down, pull the flywheel off annnnnnnd one of the magneto screws had backed out into the back side of the flywheel. Whelp, that's an easy fix, do both magneto screws up with loctite this time and put everything back together and put the engine back in the bike and fill the tank with pre-mix (cause the pump is dead, I will rebuild that over the winter).

Here is where the fun starts, it made about two puffs while kicking and that was it, nothing after that, even with starting fluid. Ok, back to this mess, check spark, got spark, have fuel (starting fluid), nothing. Check compression, 115psi, not bad. Maybe timing got messed up, check that, oh, that sharpy mark on the flywheel is 1.8mm BTDC, good job past me. Clean the points with a super thin fine file and then set the timing, it was off. Probably from the magneto getting out of place. Anyway, now I have nice strong spark set at the correct time again, more starting fluid and

Ok, recheck compression and it's 90psi now. The heck? Spin it over fast with a drill, yep, 90psi. Put half a CC of 10w30 in there cause maybe the oil from when I put it together gave me my first good compression number? Yep, back up to

TLDR: Took the top end off cause I thought I had sized it, turned out to be magneto screw backed out into the flywheel. Put everything back together and now compression is only 90psi and I cannot get the bike started when it was running great just the other day. What are the odds rings will fix my problem or should I look elsewhere?

Also, what material are the rings made of for these? If they are chrome I need to deglaze, if they are cast iron, should be able to just slap them in and go.

Leaving this open ended cause I am sure there will be several more problems I run into on this bike (I already know the blinkers aren't working right and the front fork seals are shot. It will be fun seeing what other issues I find as I resurect this bike)