HRC carb castings differ internally to the stock items, which is why the jetting can vary quite a lot from what you may use with standard carbs. 88, 89, and 90 HRC carbs all differ from one another too. As Paul says, you're much better off just using the stock carbs and air correction. It just works so well, even up to 70hp.
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Andy.
NSR-WORLD.COM
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