{"id":48578,"date":"2018-04-11T20:49:16","date_gmt":"2018-04-11T11:49:16","guid":{"rendered":"https:\/\/www.decoboco.info\/en\/?p=48578"},"modified":"2026-09-24T13:45:08","modified_gmt":"2026-09-24T04:45:08","slug":"gsx250s-katana-sunstar-premium-racing-disc","status":"publish","type":"post","link":"https:\/\/www.decoboco.info\/en\/20180411\/everyday-events\/gsx250s-katana-sunstar-premium-racing-disc","title":{"rendered":"GSX250S Katana Sunstar Premium Racing Disc Carburetor maintenance + OH polish"},"content":{"rendered":"
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\nThis is from the additional work we did. Sorry for the wait.<\/p>\n

<\/p>\n

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\nIf it can be installed, we’ll upgrade to T=5.5MM. There’s a slight weight increase, but it feels more solid, resists warping better, and even as it wears down, it doesn’t feel sloppy. It has good longevity.<\/p>\n

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\nIt feels like ages ago, but… we wanted to remove the rear brake pedal shaft and lubricate it. But you can’t get the shaft out without removing the rear suspension and raising or lowering the swingarm\u2014then you can’t remove it without taking off the rear master cylinder too\u2014then that bolt won’t come out\u2014a rusty M6 snaps\u2014we tried centering it but it still won’t come out\u2014so we ended up digging it out and doing a helicoil, which was a long process…<\/p>\n

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\nWe also replaced the master piston cup.<\/p>\n

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\nIt came out nice and clean.<\/p>\n

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\nIntake manifold replacement\u2014a worrying job. It’s one of those tricky Suzuki situations with “countersunk screws & Loctite.” I used to struggle with these, but nowadays I’d say I can get 983 out of 1000 out.<\/p>\n

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\nWhether there’s a next time is unclear, but I went with steel countersunk hex bolts. If there’s any spot that might corrode, be careful with SUS304.<\/p>\n

Removing corroded stainless steel that’s seized in a tight spot is literally hellish.<\/p>\n

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\nWe removed the carburetor. It’s a pretty cute BST carb. But man, it’s dirty…<\/p>\n

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\nWhat kind of gunk is this? It looks really oily…<\/p>\n

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\nFirst wash is done. We can finally see the condition of the body.<\/p>\n

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\nThere’s some light rust sediment. It’s within acceptable limits, so we’ll just install the OEM filter.<\/p>\n

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\nCarbs #2 and #3 have the shaft running through and locked with a nut. This is pretty tricky because you want to remove it without putting stress on the butterfly, then loosen it.<\/p>\n

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\nSince it has grooves cut in it like this, you feel this weird flexing sensation in your hand, which is really uncomfortable. I have a jig made for BST36 and up, but not for this size, so first we make one.<\/p>\n

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\nOn the lathe, finish the inner diameter to a snug fit, then just cut a groove to match the grooved shaft width.<\/p>\n

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\nIf you can buy peace of mind for 15-20 minutes of work, you should make it. Peace of mind for you and me both.<\/p>\n

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\nSolid mounting makes loosening safe. And tightening is safe too.<\/p>\n

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\nPretty high mileage on this one\u2014over 60,000 kilometers. OEM carbs really do have excellent durability.<\/p>\n

The slide valve and block are still in great shape.<\/p>\n

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\nIt might even be better than new. A nice finish is always better.<\/p>\n

You can’t feel the performance unless you touch it or ride it, but the appearance stays in photos and looks good. I think it builds attachment too.<\/p>\n

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\nFor fine rust, this OEM Mikuni filter is effective.
\nIt’s not suitable for heavy rust. The rust clogs the filter and reduces flow, so watch out.<\/p>\n

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\nWe adjust the fuel level on all four carbs and we’re done.
\nMan, the fuel level was crazy high though.<\/p>\n

We’ll assemble it tomorrow and if there are no issues, we’re finished.<\/p>\n","protected":false},"excerpt":{"rendered":"

This is from the additional work we did. Sorry for the wait.<\/p>\n","protected":false},"author":2,"featured_media":48547,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"pochipp_cv_data":"","swell_btn_cv_data":"","footnotes":""},"categories":[1924],"tags":[136,135],"class_list":["post-48578","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-everyday-events","tag-carb-maintenance","tag-sunstar-kit"],"_links":{"self":[{"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/posts\/48578","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/comments?post=48578"}],"version-history":[{"count":0,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/posts\/48578\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/media\/48547"}],"wp:attachment":[{"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/media?parent=48578"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/categories?post=48578"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/tags?post=48578"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}