SJ running weak

[shockwave538]

Having an issues with my SJ. Had been running well for about a year since rebuild, could’ve used some minor tuning but pretty good overall. Recently pulled the engine to rebuild my midshaft. Now it feels weak. Has almost no bottom end, and tops out at 39 mph, had previously gotten it to 42-43. Compression and spark are normal. Checked all exhaust parts for leaks, and riding with hood off didn’t help. Fuel check valve and filter are clean. Haven’t broken into intake yet. TIA

90 SJ, stock 61x/62t with lightened flywheel,
Dual 38’s, 1.5 N/S, gold spring, 130/70 jets

 

[shockwave538]

Update: Pulled intake and reeds were fine. Gonna check carbs next. What in there could maybe cause this? Or something somewhere else?

 

[shockwave538]

Everything on side of carbs looks clean. Also pulled grate, prop and wear ring are normal. Next thing could possibly be a bad exhaust gasket? Please, anyone else have a thought?

 

[DylanS]

Everything on side of carbs looks clean. Also pulled grate, prop and wear ring are normal. Next thing could possibly be a bad exhaust gasket? Please, anyone else have a thought?

Resolved? Any cavitation? Maybe midshaft isn’t sealed well. Did you do a leak down test?

 

[shockwave538]

Went through everything down to head and exhaust off, found nothing. Checked electrical again, coil secondary read open even though it was running both cylinders and showed sparks. Later tested everything in ebox, all good readings. Buddy thought maybe stator was running weak though it tested ok, which may also explain the various electrical failures I’ve had in my last ~40 hrs. Having someone good go through everything in there now, stator is the last thing left. I the meantime, I just got my ADA head and B pipe installed!