Between them, Jackson (137no) and new overseas player Schmulian (153no), born in Cape Town but who has lived in New Zealand from the age of nine, smashed 32 fours and six sixes as they beat the record 304 set by Undercliffe’s Mark Gilliver and Mark Chapman in 2000.
Methley responded gamely but still came up 88 runs short.
Champions Pudsey St Lawrence were given a fright by Bradford & Bingley after being restricted to 178-9 which included a half-century from Barrie Frankland.
Muhammed Afridi hit 68 in Bees’ reply and they were just four short of victory when Archie Scott took their last wicket off the penultimate ball.
Christian Silkstone hit seven sixes in making 108 and put Lightcliffe on the way to a 33-run win over Undercliffe, and a 5-18 spell from Conor Harvey saw Farsley crash out for 75 in reply to Townville’s 136.
With Azeem Rafiq taking 5-54, Wrenthorpe came up four runs short of victory against Cleckheaton despite the efforts of Irfan Amjad (68no).
Josh Holling took 6-35 as New Farnley were dismissed for 145 and Hanging Heaton recovered from 14-2 to chase down the revised target with four wickets in hand.
Simon Tennant hit a century and took 4-31 as Woodhouse Grange put down a marker in Yorkshire North with a 141-run win at defending champions York.
Mark Jackson (76) and Will Hunt (79) led Sessay to 258-5 and even an unbeaten 107 from Umair Khan could not stop Castleford dropping short.
A century opening stand between James Wharton (49) and Finlay Bean (62) looked to have put Yorkshire Academy on the way to topping Stamford Bridge’s 195 but James Keast turned things round with a 5-53 spell.
Sam Drury’s century and David Snowball’s 5-14 came to nothing as Scarborough’s domination of Beverley Town was halted by rain.
Tom Geeson-Brown (4-32) was Harrogate’s top wicket-taker as they dismissed Dunnington for 147 to win by 75 runs while Clifton Alliance won by three wickets over Sheriff Hutton Bridge, who were bowled out for 123 after being 70-2.
A 5-47 spell from James Stuart saw Sheffield Collegiate crumble to 122 as Doncaster Town maintained their 100 per cent start in Yorkshire South.
Haseeb-Ur Rahman (100no) and captain Sam Drury (138no) put on 245 as Treeton raced to 324 and a comfortable win over Elsecar.
Whitley Hall needed nine off the final over with one wicket left to overtake Wakefield Thorne’s 225-8.
But Greig Batty (60) was caught by James Wolfenden with them still five short.
Mark Cummins hit a half-century as Tickhill eased past Hallam’s 126-8 and Harpreet Singh Bhatia top-scored with 60 as Barnsley beat Aston Hall.
Louis Kimber (60) was the main contributor to Cleethorpes’ 202-8 and even though Dave Rodgers responded with a half-century, Wickersley fell 20 runs short.
In the Huddersfield Premiership, Steve Whitwam followed up a knock of 66 with a 4-45 spell as Golcar beat Shepley.
Marco van Bijon took 6-19 as Almondbury Wesleyans slumped to 98 and even though Frederick Walker (5-30) raised hopes of victory, Armitage Bridge scraped home by one wicket.
James Grosvenor (110) and Siraj Sajid (43) led Moorlands’ successful chase of Kirkburton’s 264-5 in which openers Andy Smith (73) and Alex Schofield (140) put on 170.
A sixth-wicket stand of 89 between David Hester (60) and Chris Thompson (47) helped Aire Wharfe champions Otley to victory over Rawdon.
James Hall (55no) and Paul Dover (33no) steered Ilkey to a three-wicket win over Adel and into second place in the early table.