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@BrickMan
Finally figured out why my old bike runs bad occasionally, giving symptoms of lean AND rich seconds apart from each other....
1) Someone previous has changed carbs to another of same make and model, but different variant which had a vacuum pet cock on it, found this really early one, blocked it, but then found internally with the carb today that the spring thats mean't to keep its little flap shut was broken. So depending on load its been pulling vacuum down on the cv bellows on one carb, roll on throttle slow = no problem, jump on it = behaves like shit.
2) Both emulsion tubes worn, some holes too big from wear, main bore down the centre ovalised and then a pile of gritty congealed old fuel jammed near the base.
3) Needles worn (changed them a few years ago, but think the worn emulsion tubes have really made them wear fast).
4) Had altered needle height severely myself to try and get it leaner (as always running rich).
5) valve clearances way off on one exhaust valve, cam lobe is potentially keeping it open as zero clearance in it. The other exhaust valve is perfect though. Both inlets are slightly tight, only just off bottom of spec.
6) blown out gasket between manifold and rear pipe.
Will see what happens when I put it all back together with all new bits. Graphite doughnut for exhaust cost a fortune and had to import from Germany FML. Japanese carb rebuild kits surprisingly not that bad price wise via Canadian ebay seller, quality of them feel really nice.