{"id":43746,"date":"2019-06-27T19:42:47","date_gmt":"2019-06-27T10:42:47","guid":{"rendered":"https:\/\/www.decoboco.info\/en\/?p=43746"},"modified":"2026-09-24T13:45:15","modified_gmt":"2026-09-24T04:45:15","slug":"gsx-r750l-oil-cooled-maintenance-carburettor-oh","status":"publish","type":"post","link":"https:\/\/www.decoboco.info\/en\/20190627\/everyday-events\/gsx-r750l-oil-cooled-maintenance-carburettor-oh","title":{"rendered":"GSX-R750L Oil-cooled maintenance carburettor OH"},"content":{"rendered":"
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. <\/em>

Always going all the way to Tokyo… thank you so much. <\/em>

Especially for new customers…
motorcycles have a way of breaking down somewhere else right after you fix one thing. When that happens after we’ve done work, if the distance is too far to say “take a look and bring it in,” it starts to feel irresponsible lately. Don’t you think?

Honestly, I think the best approach is to find a familiar shop within a distance you can actually reach. <\/em>

This time, we’re handling oil-cooled maintenance and carburettor maintenance. <\/em> <\/figcaption><\/figure>\n\n\n\n\n\n\n\n
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Doing a carburettor OH means replacing the intake manifold and accelerator cable as standard.
You can’t do it without removing the carb anyway. As always, just use a 1\/2 breaker bar and a +3 box and crack it loose with a bang! You should be able to get everything off without any trouble in a second. <\/figcaption><\/figure>\n\n\n\n
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The intake manifold and things like that will probably become unavailable eventually. Same with the accelerator cable. The gratitude for genuine parts that you can look up the part number, get them delivered, check them, and use them right away…
When they become discontinued, you’ll be grinding your teeth thinking “I should have bought them when I had the chance.” That day might be coming soon.

Oddly enough, list prices go up too, so you might not lose out. <\/figcaption><\/figure>\n\n\n\n
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For easier removal in the future, I’ll swap the mounting bolts for flanged hex bolts. <\/figcaption><\/figure>\n\n\n\n
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The BST vacuum carb is a racing vacuum carb that I like to think has kept evolving.
This large body in particular has a suspicious vibe to it. You can change the main jet from below… you can add a power jet after the fact, and with the RK you can quickly remove the needle with the top cap, and so on\u2014it’s got everything. <\/figcaption><\/figure>\n\n\n\n
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Stock carburetors are mostly Phillips screws. You need to be careful because they strip easily.
I think it’s better to loosen them with an impact driver as much as possible. They usually come loose.
If you can muscle it with arm strength and get it off, that’s fine too.
\u2022 Don’t strip it
\u2022 Save time and work quickly
\u2022 Use a shock driver so you don’t impact the body
\u2022 You can watch the disassembly work objectively and feel confident
I think there are more benefits.

“It was so tight I couldn’t get it off, it was a real hassle”\u2014then extra labor charges. <\/figcaption>Is that a matter of skill or equipment? I wonder. <\/figure>\n\n\n\n
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There’s no rust buildup in the float chamber, so I’m relieved. The tank is in good condition. <\/figcaption><\/figure>\n\n\n\n
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Lately it takes time, so I’m not pushing polishing.

“It costs money and isn’t it fine without it?” If you really want polishing done, please be mentally prepared to push back on that talk.
*I do do a light polish during cleaning, but… <\/figcaption><\/figure>\n\n\n\n
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Given the age, I think replacing the starter valve is essential.
If the carburettor body has never been taken apart into four pieces, you need to be careful with the seals and such. <\/figcaption><\/figure>\n\n\n\n
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Basically it’s dead blind, but I’m replacing the hose too. I’d probably get the same thing and price from Honda’s bulk tube ordering. <\/figcaption><\/figure>\n\n\n\n
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Since I do a lot of work simultaneously, I keep everything sorted into boxes so I don’t get confused later. <\/figcaption><\/figure>\n\n\n\n
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I painted the plates black with gun coat. Dirt doesn’t show as easily. <\/figcaption><\/figure>\n\n\n\n
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The starter valve gets a new one too. When you clean it and put in a fresh one, that smooth “whoosh!” sound as it closes is nice. <\/figcaption><\/figure>\n\n\n\n
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The wear parts of the body\u2014the gasket material\u2014are totally fine, so I’m relieved. <\/figcaption><\/figure>\n\n\n\n
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The SPG doesn’t seem to have any mixing, so I’m relieved. <\/figcaption><\/figure>\n\n\n\n
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Has it been replaced? It’s a pretty late-model float valve. The material and the holes on the side have been added. <\/figcaption><\/figure>\n\n\n\n
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This should be fine too. <\/figcaption><\/figure>\n\n\n\n
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This is the power jet blank. Or rather… power jet is pretty much obsolete these days, isn’t it? Or maybe not… I have the impression the structure is kind of sloppy? I wonder…

Adding it and getting it to work is also a good idea. That’s the fun of the BST. <\/figcaption><\/figure>\n\n\n\n
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The tank didn’t rust much, so I’ll add a filter. You can get the GSF1200 stock one.
Because it’s not rusty, that’s exactly why we add a filter. I don’t want any chance of debris getting into the carb and causing problems. <\/figcaption><\/figure>\n\n\n\n
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So once assembly is done, I’ll adjust the actual fuel level.
Honestly, looking at this and adjusting it won’t cause a “dramatic change!”

However,
\u2022 Wavering overflow (a weird symptom where the fuel level rises over time)
\u2022 Problems around the air vent (fuel level is off the same way)
\u2022 Misassembly (so-called mistakes)
\u2022 Final fuel level adjustment check for cylinders 1-4.
These are the final checks. By the way, the BST carb has a removable float arm, which is innovative(?), so the float level is super vague as is. If you want to check it, you have to push it in firmly and hold it with something. (Basically, I don’t check the BST float level.) <\/figcaption><\/figure>\n\n\n\n
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So the carburettor is complete. Mmm, it’s clean. I’m hoping it’ll rev smoothly now, and on to the next job… <\/figcaption><\/figure>\n\n\n\n
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Now for the oil-cooled maintenance. Oil-cooled maintenance is just replacing small parts and making adjustments, so don’t expect a “dramatic change!” Think of it as the bike being at 59% condition with various things worn down, and we’re making incremental 1% improvements to bring it up slightly.
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The engine damper wear was gradual. I’ll swap it for the later nut-free type. <\/figcaption><\/figure>\n\n\n\n
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Honestly, if you don’t point it out like this, people won’t notice, and even if you do it, you don’t get paid extra, but I think it’s better if both the person assembling and the owner feel good about it.
In the end, when you sell it, it becomes “this is a bike in great condition,” and that’s a plus for the future too.

It’s like looking ahead to something you can’t see, or maybe not… <\/figcaption><\/figure>\n\n\n\n
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I also replaced the starter motor O-ring. <\/figcaption><\/figure>\n\n\n\n
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The generator damper was in pretty good condition too. (I replaced it anyway.) <\/figcaption><\/figure>\n\n\n\n
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I gave it a quick buff and shine. <\/figcaption><\/figure>\n\n\n\n
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And one more thing. Running the digital temperature sensor wire next to the exhaust pipe like this isn’t really recommended.
\u2022 The appearance isn’t great
\u2022 The heat makes it crispy
\u2022 The wiring is actually pretty long, so you have to bundle it, which looks shabby
So I rerouted it on my own. <\/figcaption><\/figure>\n\n\n\n
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While I was at it, I also replaced the shift seal. <\/figcaption><\/figure>\n\n\n\n
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If you replaced the chain and sprocket, I wish you’d replaced the lock nut too. <\/figcaption><\/figure>\n\n\n\n
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Lock nut and lock washer, both folded and marked with a marker so you can check them visually going forward. <\/figcaption><\/figure>\n\n\n\n
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For some reason this GSX-R750L has a hazy acceleration feel. What’s that about? That hazy feeling.
The carb was just torn down, the ignition timing area hasn’t been touched, so let me just check the gear count. So I pulled the idler and counted 1, 2, 3… no problems. (Relieved.) <\/figcaption><\/figure>\n\n\n\n
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Suzuki’s idler gears are really solid, you know.
I hear Kawasaki’s air-cooled Z-series bikes are “tough! robust!” and all that, but… is that ancient history?
Aluminum with stripped threads\u2014what’s up with that? <\/figcaption><\/figure>\n\n\n\n
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Moving on to valve clearance adjustment.
IN#1 Seized <\/figcaption><\/figure>\n\n\n\n
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#1 EX Seized <\/figcaption><\/figure>\n\n\n\n
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#2 EX Seized <\/figcaption><\/figure>\n\n\n\n
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#2 IN Seized <\/em> <\/figcaption><\/figure>\n\n\n\n
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#3 EX Seized <\/em> <\/figcaption><\/figure>\n\n\n\n
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#3 IN Seized <\/em> <\/figcaption><\/figure>\n\n\n\n
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#4 EX Seized <\/em> <\/figcaption><\/figure>\n\n\n\n
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#4 IN Seized <\/em>

So they were all seized. What happens when they seize? They gradually wear down and become low-cam. Especially the rocker arm slider wears more than the cam, and the tapping noise increases. This tapping noise is a weird kind of wear that valve clearance adjustment can’t fix.
With rocker arm-type engines, the noise might actually be coming from rocker arm wear more than from valve tapping.
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The cylinder head was relatively clean inside. <\/figcaption><\/figure>\n\n\n\n
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The cam chain is loose, but the auto tensioner isn’t taking up the slack.
I tried pushing from the back to adjust it, but it won’t budge… which makes me a bit uneasy.

I was worried the slider might be broken, but it’s fine, so don’t worry. <\/figcaption><\/figure>\n\n\n\n
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Like this, the teeth and spring are performing together. I hate how the standard tensioners on Katanas and Zs are so big. Honestly, I think manual tensioners are the easiest.

It wasn’t moving much, so it must have been stuck. <\/figcaption><\/figure>\n\n\n\n
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When you take the tank off and the breather is dirty, it’s a downer. I think the owner should take care of the visible parts, and the shop should take care of the hidden parts, so everything comes out clean overall. <\/figcaption><\/figure>\n\n\n\n
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That’s how it is. When something’s clean, it’s actually hard to notice\u2014a strange phenomenon.
I think it’s because when it’s dirty you notice the difference, but when it’s clean it blends in. <\/figcaption><\/figure>\n\n\n\n
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I painted the head cover bolts black with gun coat. And also…
The head oil passage gasket\u2014the stock one is aluminum and large (big outer diameter).

It’s soft and the large outer diameter means it deforms\u2014kind of like a spring washer\u2014which feels weird, and sometimes it seeps a little…
I’ve been doing this for a while now: swap it for a copper gasket and match the bolt seat and gasket outer diameter so you can press it firmly and it won’t leak. <\/figcaption><\/figure>\n\n\n\n
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I was a bit concerned, so I turned down the bumps on the lathe. <\/figcaption><\/figure>\n\n\n\n
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Nobody asked for it, but… since I can’t discount the price, I make up for it with the quality of the work. <\/figcaption><\/figure>\n\n\n\n
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That’s how it feels good. <\/figcaption><\/figure>\n\n\n\n
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The Yoshimura slip-on was a bit dirty, so I electropolished and polished it. <\/figcaption><\/figure>\n\n\n\n
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The bracket bend looked natural, which means it was bent, so I straightened it. <\/figcaption><\/figure>\n\n\n\n
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I adjusted the sync and changed the needle position and did various other things to make it a normal bike.
The GSX-R750L is nice…

I kind of understand why the 750 is so popular. That wraps up this job. <\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":2,"featured_media":43677,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"pochipp_cv_data":"","swell_btn_cv_data":"","footnotes":""},"categories":[1924],"tags":[136,91,1919],"class_list":["post-43746","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-everyday-events","tag-carb-maintenance","tag-gv73a","tag-oil-cooled-maintenance"],"_links":{"self":[{"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/posts\/43746","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=43746"}],"version-history":[{"count":0,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/posts\/43746\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/media\/43677"}],"wp:attachment":[{"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/media?parent=43746"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/categories?post=43746"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/tags?post=43746"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}