If you have no PJ's and stock #128 MJ's, then you are asking for trouble!
I have rebuilt 2 motors in the last 12 months for people who have suffered blockedPJ's due to dirty fuel! Both motors went pop on full throttle at high rpm.
Get some big mains in there, or the PJ's back in place. Also consider re-plumbing the air corrector hoses back to the stock configuration, or at least set them up as recommended by HRC with the rest of their settings.
Stock NSR250 jet settings can be found in the new Technical section. I guess I better look at doing some diagrams to show the stock plumbing next!
Andy.
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