Toilet not dumping water

[hovel in a bog]

My elderly Dudley 88 failed. I know now I could just have replaced the flapper, but I bought a new one. Fitting was pretty easy, but it just does not dump the water, trickles out, not fully round the bowl, and just carries on and on. I have found if I lift the ball valve to stop the water entering, the syphon does go glug glud and stop eventually. I am left with a stirred up tissue in the toilet at best.
I have checked the water level is right, the outflow is clear, the pipe down from the cistern is clean, under the rim is clear. The lift of the piston is straight and the right height. I cannot find anything else to fiddle with.
Any ideas?

 

[CBW]

Did any of the previous syphon diaphragm get through to the pan/flush pipe? Photo of new syphon arrangement? Is it dual flush?

 

[hovel in a bog]

Thank you so much for replying. The old Dudley 88 still had its diaphragm, with a split, but it still dumped the water, although needed a few pumps which is why I changed it. Not a dual flush. I have looked at a number of videos on the 88 and am sure it is fitted correctly (difficult not to really!). It looks exactly like the old one. The tank it sits in is an old "new reverso" made of some sort of bakelite I think.
I have now found that if I run the cold bath tap fully, the syphon does reset, but it still does not dump the water. I have tried different levels of opening the stop cock (which is outside) but this does not seem to make a difference.
I am beginning to think I should just dig a hole outside!

 

[CBW]

You didn’t fit the old one by mistake did you? Check the new one has a diaphragm. I can’t see why opening a bath tap would help with the siphon. Check the lugs on the siphon too.

 

[Fred Blogs]

The only two reason that a siphon type valve that you have wont work is the delivery pipe is blocked or the bit of bent wire from the handle isn't lifting the diaphragm enough.

 

[hovel in a bog]

No, the old one is sitting on the shelf. Have checked the diaphragm, the yellow lever is pulled straight up to the full length to lift the diaphragm. I have checked all pipework is clear. New ball valve lever etc, water flows well into the tank.
If I dont let water return to the tank by holding up the ball valve, the syphon does reset and stop trickling water into the pan. Otherwise it is a continual trickle and fill situation.
I dont seem to have lugs...

 

[jeff the gasman]

You’ve pushed the flush pipe too far into the pan.

 

[hovel in a bog]

Thank you for your response. I thought about that and measured it, it is 0.4 in the cystern and exactly where it was before in the pan, but I will give it a go pulling it further out.
Back to the stop cock in the road....
Is water supposed to shoot out around the yellow pin that lifts the flapper?