Not sure how to check for a clogged exhaust beyond what i've done so far, took the little silencer cap thing off the end, looked in there, turbine core is unplugged, it's got a wicked pop at idle and it's all coming out the end, honestly doesnt seem like its backing up at all. With a timing light on it at idle it'll sit flashing happily about 20-30 degrees BTDC. When you rev it it'll start to move towards advance about 10 degrees BTDC, then high RPM it'll whack over to full advance (where you set it to in the first place, actually) around 4-5 degrees BTDC. It's not any more erratic than any other ignition i've seen. Its for the most part spot on, but you do get some 180* ignition pulses every now and then.
I don't like inline filters either, but the tank is old, and theres quite a bit of rust in there. It doesnt feel like it's running out of gas, it'll just keep running like it does as long as i have the throttle pinned, back off and it'll still do it for a bit then clear up and putt nicely.
Dunno the needle or the needle jet size, i'm assuming its stock (doesnt look funny or different than the fisches or used parts i've pulled up on ebay). Stock carb (vm32) stock slide, stock cutaway. Float height is good, starter jet is stock, main jet is a 155, been told it is supposed to have a 170.
How do i Actually check a blocked exhaust. I can picture in my head the exhaust stream backing up under heavy load, flooding the motor, then clearing out when you back off the throttle. It sure does sound cleared but i dont know for sure.
The chinese CDI idea is very intruiging, is it literally as easy as just plugging the appropriate wires in from the harness to the box? Are the timing curves appropriate? I'd be shocked and amazed that it just so happens the ignition coil and pickups of a 1975 yamaha just happen to work with a modern AC ignition sysstem. I googled it a bit and found a yamaha zuma 5 pin cdi for two strokes, would that be an appropriate fix or does my CDI sound fine. I don't want to rip out stock equipment and mess up the harness for no reason.