Lots of black smoke (hard to start)

[Nauty]

Hi. I've just rebuilt a Z482 to go in my boat (engine is a Beta 10)
Sorry for it not being an orange tractor although I do have a Kubota front cutting mower as well.
I got it in a sorry state although hardly used, 144hrs.
Bores were de-glazed , new rings and new gaskets all round. Put it all back together and set it up with water for cooling and the control panel supplied.
So it belches out black smoke and won't start unless I use lots of heat. When it runs it's fine, not much smoke, responds well to throttle and no issues at all.
Then if you turn it off and go to start it again immediately , it belches out black smoke and won't start unless you use lots of heat again. I'm thinking it's getting way too much fuel on start up.
I removed injectors, ultrasonically cleaned them although they were very clean and all seemed good with them.
Still exactly the same issues.
Any ideas anyone.
I didn't touch the injector pump , just put it straight back on with the same shims.
It's never been torn down before I did it.

 

[whitetiger]

A lot of black smoke can be too much load on the engine while starting, inadequate glow plugs, timing off, restricted air intake, injectors, injection pump, low compression, etc.
Cleaning the injectors in an ultrasonic cleaner is just a feel-good action. It is a waste of time, the injector must be popped off to check the pressure and spray pattern. They can shine like a diamond in a goat's butt and not function at all.
You should perform a compression test and have the injectors professionally tested and calibrated. It is very likely if you had the engine completely disassembled, the timing gears are timed incorrectly.

Check the air intake for obstruction.

 

[Nauty]

A lot of black smoke can be too much load on the engine while starting, inadequate glow plugs, timing off, restricted air intake, injectors, injection pump, low compression, etc.
Cleaning the injectors in an ultrasonic cleaner is just a feel-good action. It is a waste of time, the injector must be popped off to check the pressure and spray pattern. They can shine like a diamond in a goat's butt and not function at all.
You should perform a compression test and have the injectors professionally tested and calibrated. It is very likely if you had the engine completely disassembled, the timing gears are timed incorrectly.

Check the air intake for obstruction.

Thanks for the reply
No load on engine at all.
Timing was done correctly and once started runs perfect.
New air filter
I guess I could get the injectors tested , just no one within 80 miles of here that can do it , same for compression test.