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1971 Honda CB450 K4 - Return to Stock

Mike

Mike

Veteran Member
Joined
Jun 1, 2020
Total Posts
134
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Location
Pittsburgh, PA
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I've decided it's time to return my 1971 Honda CB450 K4 back its original stock form. Above is a picture from this morning. Not heavily customized by any stretch but certainly not stock.

Below is a detailed list of the modifications. None of them permanent, and all of them easily reversible.


  • 1968 CB350 K0 Headlight Shell (61301-286-670A)
  • 1968 CB350 K0 Headlight Assembly (33100-286-672)
  • 1972 CB450 K5 Fuel Tank
  • 1972 CB450 K5 Side Covers
  • Mikuni VM32 Round Slide Carburetors (pre-jetted, replacement carburetor boots)
    • Light Throttle Return Springs (VM34/06)
    • Choke Cable Adapters (002-351)
  • Custom CNC machined aluminum boot adapters (Bruce)
  • 2-1 throttle cable (SpeedMotoCo via Amazon.com)
  • Choke cable (PU Universal Choke Cable for Mikuni Dual 28")
  • K&N RC-1252 High Performance Air Filters
  • Custom air filter adapters
    • 6063 Aluminum Pipe: 57mm(OD) × 53mm(ID) × 300mm(L)
    • 4-PLY 2.25" x 12" LONG TURBO/AIR INTAKE BLACK SILICONE HOSE
  • Renthal Street Handlebars - Ultra Low - Silver
  • Redwing KM-C 330 rear shocks
  • Digital voltmeter

This was mostly of an exercise in curiosity a handful of years ago.

Mechanically this bike is in excellent condition. Relatively low miles and as far as I can tell the engine has never been apart. It runs fantastic and revs to the red line with no complaints, though I have rarely pushed it that far.

I also plan to install a modern regulator/rectifier and swap over to LEDs for the gauges, indicators, and tail light as I typically do nearly all of my bikes.

This will be my "hot weather" project for the next month or so. Something to work on when it's too hot to gear up and ride.
 
Here's a look at the carburetor and air filter setup I was using. It allowed me to maintain a relatively factory appearance and position the air filters neatly behind the side covers.


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Real nice job of doing the mods, should be fun watching you un-do them.
 
Just curious why you are going back to stock? Just to do it, or are you also restoring?


Sent from my iPhone using Tapatalk
 
Nick_Brox said:
Just curious why you are going back to stock? Just to do it, or are you also restoring?


Sent from my iPhone using Tapatalk
Click to expand...

I think it's mainly down to changing tastes. I have a greater appreciation for stock bikes these days. If I needed to hunt down all of the parts to make the switch back to stock I'd probably think twice because the cost would quickly stop making sense but I have everything on hand to do the job.

In addition to that, the Mikuni VM32 carburetors aren't as conducive to my riding style these days. In my experience they are much better for more aggressive riding and I'm much happier just putting around town. They also seem much more sensitive to temperature and humidity which adds a layer of fiddling throughout the riding season.
 
Getting things together for the switch over to LED bulbs for the gauges, indicators, and tail light.

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Mike, I left one bulb in mine - the neutral light. The LEDs are nice for gauge illumination but the neutral light would blind you at night :frown:
 
ancientdad said:
Mike, I left one bulb in mine - the neutral light. The LEDs are nice for gauge illumination but the neutral light would blind you at night :frown:
Click to expand...

Yeah I noticed the same on mine. Going to switch to the regular bulb for neutral. High beam and indicator will be left LED.


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ancientdad said:
Mike, I left one bulb in mine - the neutral light. The LEDs are nice for gauge illumination but the neutral light would blind you at night :frown:
Click to expand...

Probably not a bad idea. I may also need to leave a regular bulb for the high beam indicator on this bike as well. The LED bulbs are longer than the original bulbs and don't fit well inside the little 90 degree rubber fitting that holds it in place inside the headlight shell.
 
Instant transformation:


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Here's what I'm working with. Asside from the NOS right fork ear everything is original. Unfortunately the right side of the tank has a huge dent. Not sure what I'm going to do about it at the moment.


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I love unwrapping NOS parts.


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A few close-ups for reference.


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I have a similar headlight ear, chrome CL350K4, and they all rot right where the lower rubber vibration washer sits because the way it's formed there's a gap on top that fills with water and dirt. I filled that gap with silicone sealer to at least slow down that process a few years.
 
Too bad about the dent in the tank Mike, it otherwise looks really good. That's the same exact bike and color my Dad had while I had my CL450K4 in high school, and we rode them to my first Bike Week trip in March of '72. It's a beautiful blue
 
I was fortunate that the plastic air box covers where in better shape than the original filters themselves.

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I had to walk away from the wiring task at one point. Sometimes they go smoothly, some times they don't.

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I've gotten in the habit of running additional grounds to give some flexibility in the headlight bucket. This make a huge difference when combining all the various ground connections of different lengths and eliminates some of the "pulling" you inevitably get when trying to cram everything in. I ran this one to one of the screws that secures the condenser to its bracket. I made sure to clean up all of the contacting surfaces and apply some dielectric grease.

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Getting close!

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I got as far as starting it on the auxiliary bottle. These engines run so smooth! Ran out of time for the day and wasn't able to take it around the block. I have a couple of startup videos, both before, and after the return to stock that I'll post when they finish uploading.

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Here's the first half of this project. I did a "before" startup and walk-around with the Mikuni VM32 setup and a more in-depth look at the setup I was running including the choke cable adapters and routing.

 
Question: Do the tank badge clips get installed on the tank first and then the badge is installed? Or do the clips get installed on the badge posts and then the whole assembly gets installed on the tank?
 
Clips go in the tank first, then the badge pushed into them. Father was a paint and body man :)
 
Here is the 2nd half and conclusion of the video. I'm currently working on addressing the dent in the tank. If successful I'll do a write up of that process.

 
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