{"id":45735,"date":"2018-12-29T19:31:48","date_gmt":"2018-12-29T10:31:48","guid":{"rendered":"https:\/\/www.decoboco.info\/en\/?p=45735"},"modified":"2026-09-24T13:45:03","modified_gmt":"2026-09-24T04:45:03","slug":"inazuma-1200-oil-cooled-maintenance-yoshimura-st1","status":"publish","type":"post","link":"https:\/\/www.decoboco.info\/en\/20181229\/everyday-events\/inazuma-1200-oil-cooled-maintenance-yoshimura-st1","title":{"rendered":"Inazuma 1200 Oil-Cooled Maintenance + Yoshimura ST1 Cam Installation"},"content":{"rendered":"
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\n A hidden gem, the Inazuma 1200. This is an oil-cooled maintenance job plus Yoshimura ST-1 cam installation.<\/p>\n

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\nFirst up is generator damper replacement. We’ll clean up the body too. (No image)<\/p>\n

\"\" \"\"
\nIt’s completely stiff. The engine heat has done a number on it.
\nWhen this wears out, it can get pretty noisy around idle, so definitely check it out.<\/p>\n

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\nWe’ll also replace the starter motor O-ring.<\/p>\n

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\nThe engine damper wear is moderate. We’ll clean up the case and install it properly.<\/p>\n

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\nNext we’ll remove the cam and inspect it.<\/p>\n

\"\" \"\"
\nThere’s some slight wear on the rocker arm contact points. It’s still usable, but when the cam is new, the rocker arm should be new too.
\nIt’s kind of like how when the brake disc is new, the pads should be new as well.<\/p>\n

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\nWith rocker arm-type setups, what people call valve noise is often actually the tapping sound from worn rocker arms.<\/p>\n

\"\" \"\"
\nThe cam profile is such that the contact area on the lower half of the image (the support shaft side) tends to wear harder.<\/p>\n

\"\" \"\"
\nThis is the worst cam scuffing we’ve ever seen at the shop \u2191<\/p>\n

It was a GSXR1100 that came in because of severe valve noise.
\nWhen the owner arrived, they were like “Oh, turn off the engine\u2014quick!” because it was making this rapid-fire tapping sound almost like an exhaust leak. I was shocked.<\/p>\n

It’s not ideal, but even when the cam and rocker arm scuff, they don’t seize up and cause engine failure\u2014they just gradually wear down. (Of course, the metal particles circulate throughout the entire engine.) I haven’t seen an actual seizure leading to engine failure yet.<\/p>\n

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\nThe camshaft and rocker arm are now new, and we move on to measurement.<\/p>\n

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\nWe confirm top dead center\u2014<\/p>\n

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\nNext we check the valve timing. We always set it to Yoshimura’s specified values. (The safe choice)<\/p>\n

Cam chain slack and condition, how the crank turns (whether your hand shakes and won’t stop), and even the dial position and angle when checking 1mm valve lift can cause 1\u20132 degrees of variation. To increase confidence, we measure multiple times.<\/p>\n

Strictly speaking, if the cam phase differs between cylinders 1\u20134, the readings will obviously be different. (Though we probably won’t see anything that extreme\u2026)
\nSince cylinder 4 is easiest to measure, this job’s valve timing reading is based on cylinder 4.<\/p>\n

\"\" \"\"\"\"
\nWe use the recently popular barrel polishing, which polishes automatically while we work.
\nIt’s like humanity discovering the washing machine.<\/p>\n

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\nOnce it’s clean, we spray-paint it.<\/p>\n

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\nWith oil-cooled engines\u2014or really anything\u2014unnecessary chemicals just mean extra work down the road.<\/p>\n

If liquid gasket sealant was applied for assembly, removal becomes a hassle. You don’t need to apply anything; it seats in the groove just fine. Just insert it gently\u2014nice and easy\u2014and you’re good.<\/p>\n

With the spirit that gentleness saves both people and things, go for it!<\/p>\n

\"\" \"\"
\nThe customer also ordered oil-cooled engine cover bolts. One had a stripped thread, so we helicoiled it.<\/p>\n

Honestly, I think you shouldn’t use helicoil inserts anymore. (We have no choice for larger sizes, though.)
\nTangless inserts, on the other hand, are probably so smooth that no matter who does it, 90+ times out of 100 they’ll go in on the first try, even for M6 and smaller.<\/p>\n

Plus you don’t have to break them off.
\n\u2022 They work even in blind holes (no residue left behind)
\n\u2022 No removal risk when the engine is installed for repair
\n\u2022 If you mess up the insertion, they’re easy to remove<\/p>\n

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\nLooking at the cover\u2026 what’s this? What happened? There’s some weird scraping.<\/p>\n

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\nIf you’re a bit worried, you can mark it\u2014that way it becomes a message the next time you take it off.<\/p>\n

 <\/p>\n

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\nAfter that we synchronized it and we’re done.<\/p>\n","protected":false},"excerpt":{"rendered":"

A hidden gem, the Inazuma 1200. This is an oil-cooled maintenance job plus Yoshimura ST-1 cam installation.<\/p>\n","protected":false},"author":2,"featured_media":45703,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"pochipp_cv_data":"","swell_btn_cv_data":"","footnotes":""},"categories":[1924],"tags":[],"class_list":["post-45735","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-everyday-events"],"_links":{"self":[{"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/posts\/45735","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=45735"}],"version-history":[{"count":0,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/posts\/45735\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/media\/45703"}],"wp:attachment":[{"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/media?parent=45735"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/categories?post=45735"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/tags?post=45735"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}