1990 SP backfiring and generally running like garbage

[hvguy]

Does it still charge the battery?
There's only a few things it could be.
RevLimiter
Regulator/rectifier
Relay

That engine only has a single phase charging system by the looks of it.

i checked the rectifier and its good, ( thats the aluminum square block with wires coming from it) relay? possible but the only relays are for starting and thats a large starting contactor, perhaps a rev limiter, however my luck is both of the ones i have are bad, maybe if I can find one on ebay for cheap ill replace it, until then ill just stick to the "nobody else drives this" policy

and I think your right about the single phase charging since I only saw one coil out of place behind the flywheel (2 for the spark plugs 1 for charging)

and yes its charging, I started with 12.4v, cranked the engine and it started climbing to about 13.1 or so.

 

[Mekanix]

i checked the rectifier and its good, ( thats the aluminum square block with wires coming from it) relay? possible but the only relays are for starting and thats a large starting contactor, perhaps a rev limiter, however my luck is both of the ones i have are bad, maybe if I can find one on ebay for cheap ill replace it, until then ill just stick to the "nobody else drives this" policy

and I think your right about the single phase charging since I only saw one coil out of place behind the flywheel (2 for the spark plugs 1 for charging)

and yes its charging, I started with 12.4v, cranked the engine and it started climbing to about 13.1 or so.

Wiring diagram confirms its a rev limiter.

do a google search for that model service manual and you'll see it on page 94