Best "Tool" for DIY is a Clymers Repair Manual. Tells how to leak down test, check head for warp. Not a fan of reusing gaskets, the head is a one use only gasket.
What plug you using?
Not sure on your procedure. Warm bike up on old plugs. Install new plugs. Ride WFO banging the gears, no pussy riding. When it stops pulling hard in 6th, pull in clutch and kill engine.
Read or chop plugs.
Cost of splitting cases , little bit of 3bond.
Cost of debris 10X size of bearing clearance taking out engine, minimum of$900.00 !
Plus while it's apart you can throw in new crank seals !!
Do you know why it had low compression? Just worn out?
Can't see well enough on this tablet, but is that normal/usual amount of chamfer on ex port ?
Is bad piston from dome with less carbon ?
If it was fuel mix why is one piston worn considerably more?
Was this builder assembled ? Leakdown tested before running ?
Tested before disassembly?
A quick douche with a spray can is NOT cleaning them. Must completely disassemble and soak or ultrasound. Must be able to blow air through all passages and see light through jets and sides of main jet/emulsion tube.
Not stepping on driveline toes, but what about a bowl from Yamaha? Carb parts Warehouse or Sudco?
Here's a free clue : when two carbs are 50% of one Genuine, it may be junk.
Yep, just get new fibers and steels, ditch the rubbers. Make sure to adjust at clutch, then at lever and use wet clutch compatible oil. Might be able to get good/decent clutch in S A, if not see about getting one shipped.
Well, go back through everything. Make sure everything is clean and tight. No rubbed bare wires. Figure out how to bypass both switches. Check leads to coil and coil ground.
Has feeler gauges but uses paper to set gap, why ?? Thickness of card stock varies greatly.
Where did this new coil come from ?
Have you inspected the grounds? Ohmed coil and plug caps???