'80 xj 650 running badly when warm

Had my xj for a moth or so now. It was in not the best shape when I got it. Cleaned about a sand pit full of sand out of the carbs and got it to run ok, the rubber boots from the carbs to the motor when completely split so yesterday I got them on and she runs beautiful when cold but once warm it starts to run badly. Seems like it is starving for fuel. Have not been home to check the plugs, on my way home from work ill leave the fuel petcock on prime that will eliminate the possibility of the vaccume diaphram not letting enough fuel in

Any other suggestions for what could help? Or what the problem could be?

I'll put some new plugs in next week as well and see what the coils are like

Thanks for any help

 

Classic symptom of out of spec valves. Check/Adjust valves & probably a carb clean/rebuild/sync.

Cold start circuit (choke) may be not closing fully.

Check air filter condition as well. Dont leave on prime without motor running. Might flood the crankcase with gas if the carbs need work.

Good luck.

 

Bingo. Start there. Get your valve clearances in spec, and do a compression test. Service and properly set up the carbs and you should be good to go.

But start with the valves.