The rear end finished faster than expected, so I’m moving on to carburettor overhaul. *To be honest, I should have been able to make progress on both the rear and carburettor yesterday… Things don’t always go as planned.
Alright, let’s get to work on the task breakdown (*´ω｀*)
A downdraft carburettor—it’s been a while! It’s super easy to work on
You just pull it straight out from the top, so the workability is excellent. The most difficult one is the V4. It’s pretty hated in the world too.
Since I don’t have much experience with this, I’m going to check each part carefully.
Keihin’s rationality is amazing. Even the choke holder and such are designed to be replaceable with a shared bolt—all kinds of intentions packed in there to reduce costs.
Is the carburettor linkage plate OEM? It just looks like a plain aluminum angle… I wonder what it really is.
I completely disassembled it using a Makita impact driver, but I stripped 6 out of 8 bolts… The world isn’t kind. Well, they came off easily with locking pliers.
An impact driver strikes with considerable force, so it does cause some damage to the body. The older things get, the more risk there is, so if you treat everything the same way, you can run into trouble.
If vent tubes like this become discontinued, it’s a real problem. *No issues this time. Moreover, with Honda and others, there are things like “vent tubes with different diameters.” If those get discontinued, what do you do with old bikes like that! We can’t just accept every job.
Going forward, we’ll only accept motorcycles we have some experience with, so please don’t send us anything weird.
It seemed to be running okay, but… seriously?
The inside of the float chamber has quite a sharp finish.
The main jet and slow jet are in such bad condition they look like they’re about to fall apart.
The float valve was so stuck I had to heat it to get it out. I was initially planning to reuse this part, but this time it’s being replaced.
After all, a vacuum carburettor! Fewest parts, best serviceability, best handling
Since there are basically fewer parts, the serviceability is excellent. Unlike racing carburetors with their razor-sharp acceleration, vacuum carburetors have their own advantages.
• Longer maintenance intervals People with forced-opening carburetors have very frequent maintenance cycles. OEM carburetors with air boxes can run without issues for 30,000 to 50,000 kilometers under normal use if you don’t clog them. This is a huge difference. • Altitude and seasonal changes cause fewer problems With an OEM carburettor and air cleaner box, you can ride to fairly high elevations like those around Mount Fuji and it’ll run normally. But with funnels or power filters, it’s often quite difficult. • Carburettor synchronization and other routine work is simple and workable If you want to change the carburettor settings, vacuum carburetors have some limitations. However, routine carburettor synchronization is very easy to perform. As long as you don’t need to change the settings, you can enjoy it for a very long time.
To wrap up this long post, I’m simply a big fan of vacuum carburetors, so I’m promoting them (*´ω｀*)
I gave it a light finish with baking soda wet blasting while cleaning
Baking soda media prices have skyrocketed lately, so we’re not doing cosmetic finishing on jobs. We’re just using it for minimal cleaning these days.
I’m really feeling the raw material cost inflation.
I’m a box organizer! Everything has to be square or I can’t relax
This way, even a carburettor taken completely apart can be neatly stored in one box. You won’t lose any parts, and since I organize by location in different boxes and rooms, I don’t need to remember anything.
Organize physically. Keep digital images. That way you only need a vague sense of things—memory is the most unreliable thing anyway.
So we’re on hold until the parts arrive. Feels nice and clean now (*´ω｀*)
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