CB400F, the water bike.

Rat_ranger

Coast to Coast
So I'm calling ut the water bike for the 1/2 gallon that came out when I pulled the sump off. A friend gave it to me, it had belonged to their uncle and left behind their parents garage for years. Well the uncle passed away, the bike was moved from behind the garage to behind the barn until it was offered to me. Now it sat with no starter, and no clutch cover outside in Washington. Surprisingly it wasn't locked up that bad, and despite the water the internals are all in pretty good shape. The only parts ruined by water are a few rockers, and the cam. Now my guess it got parked because the starter clutch broke. I found half of it in the sump and the rest on the primary shaft. So plans are to clean and slowly do a full rebuild, probably with a 466 kit, maybe a hotter cam since it needs replacement.

The frame has rust damage as well. I'm asuming it was on its side because the kickstand fell off. So the frame needs some repair, and is missing the swingarm. I'm not worried as I have some interesting parts for the front and rear suspension. It won't be a cafe, bobber, chopper, tracker or enduro, it'll be different simply because I have intersting parts and I'm not set on finished looks yet.
 

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Wow, you got your hands full there bud.

Im excited to see your progress. I was able to get mine fired up this morning after the rebuild.

The only advise I can give came from Kanticoy, to replace the factory tension arm w the new style aluminum.

As the factory ones had the bad habit of binding up and it takes pulling the bottom case to free it up.

Parts sources... 4into1.com davidsilverspares.com between those and ebay / amazon you should easily find everything needed to get her fixed right up.

You can get the 466 kit for $120 at cruzinimage.com

https://www.cruzinimage.net/2017/08/17/75-77-honda-cb400f-466cc-bigbore-pistons-kit-whead-gasket/
 
Yeah, probably hardest thing will be finding a new clutch cover with the actuation mechanism. Already been cruising ebay just to get a feel for prices. Also been looking at the sohc4 forum to see what knowledge is there. Sticking with carbs this time as while EFI is fun, and different, it really does add a whole new level to the wiring.

crusinimage is great, I have his pistons in my XS and they were within .0002" and .1g of each other.

I expect this will take atleast a year, more likely 2 as it will be as money and time allows.
 
Yeah I have found they can be surprisingly expensive little machines to build. :p
 
Lol, any bike can be expensive to build. Which is why I do it for a hobby, not a living. My XS was around $4k when finished, this one might end up higher. That is with doing 95% of it myself, if I had to farm out all the machining and welding it would be cheaper to buy a new bike.
 
Started cleaning parts today. I don't have a parts washer, so I settled for a dish tub and mineral spirits. Did a good job removing the old gummy oil/water mix. The crank, rods and transmission are in surprisingly good shape with no rust. I will be cleaning them again, more in depth with the tiny brushes to clean the oil passages. Included for laughs is a cb400 piston next to one from an xs650.
 

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So nice and clean.
And
Holy cow that rotor, may be a chore for the impact to pop off!
 
Yeah, I have it soaked in penetrating oil right now. I'm probably going to look at the again-moto charge system. The rotor was down in the dirt with no cover for a while.
 
Not looking bad on the crank and trans gears. My z50 was pretty similar, although not filled with water it was filled with dirt and mud. Its amazing how resilient the stuff can be.
 
Yeah it is cleaning up amazingly well. Right now I'm just using mineral spirits in a dish tub, I want to get a parts washer. But this won't be the final clean for these either, I want to get the cases vapor blasted or soda blasted and I have oil gallery brushes on the way.
 

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Sweet, your really doing a nice job. 8). Amazing how well it kept.

Did you have much trouble getting the screws out of the splash shield?

Mine were stupid tight.
 
With a little impact driver and a dead blow they came right out. One took a couple harder hits, but most case screws on old hondas are harder to get out.
 
Started working on the steering stem. Can anyone guess what front end I'm using from the lower "triple" clamp?.
 

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Nope, not a girder set up. I'll give a clue, it's from a low production early 90s Italian bike that was based on a race rep.
 
Lol, yep cx125. I'll be making my own front axle so no gilera wheel, which is fine since they were ugly. The fork tube needs replacing or polishing and rechromed. I'll have to see which is easier to do.
 

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