Thanks everyone, bike is running great now. Of corse I did find the real problem after all was just the vacuum line to the fuel tank valve, but now I have clean carbs too.
Next problem: where to find body parts for 82 sx400j, side covers, I broke the left one trying to get the carbs out (yes, I’m a dumb ass) and the right was missing when I bought the bike. I have tried e-bay but no luck yet.
What other years will fit mine if any?
And does anyone have the part numbers for these side covers?