GSX-R750L Oil-Cooled Maintenance, Deco-mainte, and Other

(*´ω`*)Chin-ma-men!

Hmm… what kind of phrase is that? What’s the name?
I’ve never actually eaten it, but “Chin-ma-men” is stuck in my head…

It’s probably something like a sour and spicy ramen.

I worked from morning to night trying to shake off yesterday’s nightmare.
I’m in trouble, folks.

So! Check for leaks before disassembling.

I don’t think there’s any mistake, but… just to be safe.

And it doesn’t leak… typical haunted bike behavior.

Well, there’s no point putting it back together. These things happen…
That’s what I’m thinking as I disassemble it.

There’s quite a bit of rust sediment. This must have been the problem.

Clink!
(‘Д’)Huh?

What’s this? Something like a press-fit air jet coming out from inside…
And there’s only one.

This BST38 (large body) has
an old-school“Power Jet”feature installed.

But that’s a screw-in type, and the L model is blind. This isn’t it.
I wonder what it is…


The #4 PS cannot be extracted. Requires machining.

It only moves with a squeaking sound.
I’ll tighten it and do my best to put it back. Same RPM and protrusion.

Extraction is possible, but it costs money, so I skipped it this time.

Not touching the diaphragm!

This is absolutely the #1 chemical you should have (*´ω`*)

イチネンケミカルズ(Ichinen Chemicals)
¥749 (2026/09/21 23:35時点 | Amazon調べ)

( *´艸`)Oh, beautiful!

Please feel free to use it~

The body of a rubber-type float valve is crucial.

Things that stroke are inherently difficult to move perfectly straight.
The contact area tends to decrease.

It’s the same as how the bottom of a fork’s bottom case wears easily.
Float valves with rubber tips have extremely high durability.
When reusing, pay attention to the shine and step marks on the body.

If you don’t understand, a new one is better.

If you’re reusing the receiving side too, try polishing it with a cotton swab and compound.
The float valve should have better sealing.

Honda OEM hoses are really useful.

Honda parts lists always include bulk hose part numbers.
“Good products at low prices, available for a long time”*Long = long length.

OEM parts are Honda! That’s a sure thing.

BST carbs have many different types of springs, so
check carefully.

There are various springs depending on the year and bore size.
Sometimes they get mixed up, so it’s best to line them up and check to be safe.

*Surprisingly, it still runs…

Looking at these springs, I think the CVR is the strongest vacuum carb…
CVK→CVR looks like a minor change, but it’s quite different.

Making the spring outer diameter much larger is nice.
Less prone to breaking in the middle (less deformation).
But what does that mean? Well…
The CVR is definitely one of the carbs you want to get your hands on.

Time passes… leak check.

If you do it properly, a carb overhaul becomes quite expensive.
This is the second one.
I did the work with minimal effort while maximizing performance.

The float chamber is also wet, so it’s nice and clean.
No leaks and perfect!

Oh no, it broke~

I don’t care at all. It’s old, so this part will break anyway.
Normally.

So I chamfered it and helicoiled it with M5-0.8.

Restored with Honda OEM vacuum takeoff.

By the way, the large body is thick enough to allow this, but
the small body might not be able to.

I usually have BST and CVK parts in stock.

Problems come up sometimes.
For example, different tuning springs installed,
fuel joints cracking,

there are lots of gremlins.

Without a manual, you can’t verify anything.

You need to know what’s currently installed. Is it normal? Abnormal? STD?
The mystery deepens…
It’s best to get a manual.
Old import bikes are tough…

*Everything was STD. (Import)

All done!

The starter motor seemed to have poor grounding.
You might think that’s impossible, but with old bikes, unimaginable things can happen.

Running great! Exorcism complete!
Now I just need to make the invoice and we’re done.

(‘Д’)It’s been a while since I got stuck like this~

イチネンケミカルズ(Ichinen Chemicals)
¥749 (2026/09/21 23:35時点 | Amazon調べ)
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