Topic: IDK Numero Dos - 1975 Honda CB400F

[SOHC4 Cafe Racer Fan]

Take it easy doing burn outs on that back tire. 

[minimo]

SOHC Fan, hahah! Might be easier to do a burn out to replace the tire than to try and muscle it off with my angle irons

Thanks for the compliment, spuds. I’m kinda liking the profile too. I think what I’m envisioning is sorta coming into play on this one.

Strynboen, very good point. While I was worried about sand getting into the frame from media blasting, sure, moisture/water would be something too. Where would the lowest point be to drill the holes, in what fashion and what size drill bit would you recommend?

Thanks!


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[strynboen]

5 mm holes..is fine but better to seal a bit up..and,,,yes... do both..

[minimo]

5mm sounds good to me. Thanks.

And SOHC Fan, good on the rear clearance reassurance. Thanks!

Meanwhile... Vapor blast, eat your heart out.
Looking for sponsorships from Dawn dishwasher soap and 3M Scotch. Ha!



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[minimo]

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[minimo]

And u know I meant 3M Scotch Brite. Darn oily fingers.

Sláinte!


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[minimo]

Incremental progress on some wiring and relocation of things. A generous pruning of the stock wiring is going to allow for some tight cramming in the tool tray underneath the seat.

Dreaming of a Motogadget unit some day for one of my bikes, maybe this one if it’s worthy. Finally got a decent relocation of the Shorai LFX battery - I recycled the seat hump thingy that I had chopped from the frame rear, shaved off the helmet holder tab and bits, flipped it upside down and bolted it to the frame slightly in front of and above the rear wheel making a little ledge.

Will add some foam padding to this batt mount later. Hope that it clears the tire at bumps. I think it should - I haven’t given it the sit on and bounce test yet. The battery will get a nice and robust rubber strap similar to the OEM one but it’s gonna be a zip tie for now.

Also slapped on some new carb intake boots. I’m using stainless steel socket c/s to replace the old screws that were a bear to remove. These new stainless screws each received a generous application of some zinc compound to help minimize galling.
The rack of carbs went on next. Still got the throttle linkage and airpods to deal with and other doo-dads...

Aiming for a start up and a light ride around the block by this weekend (on these bald ass rubbers).


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[slikwilli420]

5mm sounds good to me. Thanks.

And SOHC Fan, good on the rear clearance reassurance. Thanks!

Meanwhile... Vapor blast, eat your heart out.
Looking for sponsorships from Dawn dishwasher soap and 3M Scotch. Ha!



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Looks good now, but will corrode without maintenance fairly regularly. The vapor blasting process peens the surface and reduces oxidation to far greater extent than the process you used. Sure it was free now, but I prefer maintenance free finishes, especially in places were you dont want to go back and polish later.

[minimo]

Thanks for the note, slikwilli420.

Not pictured was the double coat of DupliColor Engine paint. Hoping this will keep the oxidation at bay for a little while.

[slikwilli420]

Thanks for the note, slikwilli420.

Not pictured was the double coat of DupliColor Engine paint. Hoping this will keep the oxidation at bay for a little while.

Agreed! Disregard my prior comments. Paint will do just fine for many years.

[minimo]

I won’t be mounting a front fender so I had to stabilize the front end somehow.
Enter Tarozzi fork braces.

This one here, Tarozzi 22-0040 is meant to fit a 1982 Honda CB400N but it had the same measurement specs as a 1975 400F and seems to be a match well made. Here are my measurements as follows:

Tube diameter 33mm
Mounting diameter 56mm
Center distance 172mm

There are “arched” versions of these fork braces, that is if you wanted to keep your front fender mounted underneath the arch of the brace. However, it seems that there is not an arched version available for these specific dimensions noted above, just FYI. For my ‘77 CB550F there is an arched version available which looks cool even without a front fender installed IMO. However, keep in mind that at bumps you’re likely to run into clearance issues with the fork brace coming into contact with your lower brake line bolt...

I purchased my fork brace from Fast From The Past. Excellent service - fast shipping.


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[minimo]

Fab’d a seat pan out of fiberglass. I glassed in some knurled nut inserts for mounting - just two of them. I will try to make a keyway to register with some part of the fuel tank so that that part of the seat locks into place, but this is it for now.

Also blocked out the seat padding with some L400 foam. It’s a bit firm but I like that. Not settled on the shape yet, thinking a more acute angle from the tail light section toward the front so it’s not so bulbous. It’s a start.




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[strynboen]

yes think the tank sqvared form must be transformed a bit in to the seat...those raund forms..dont fit the overall Sharp look..mine 400 had a more Sharp form..but are too long for your frame chop..

[minimo]

Will definitely think sharper on the seat edges, strynboen. Good call. Thanks!


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[minimo]

Strynboen sensei? How does this look?

I’m probably going to ask to get at least a 1/8” of padding to smooth out any cracks/seams that may show thru the pleather. I’m thinking of using Naugahyde or even real leather. Any recommends?


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[strynboen]

go for a test ride..before make the last finish...komford vas the proieitet, for putting seats on bikes ...nowdays look is the top prioetet..thats vhy hipsters stand up riding...

the real riders find kompromies..or have more seats to thange aut..after riding distances

[minimo]

Thanks, strynboen.
Hopefully getting a first ride in this weekend. Keep you posted on ride and comfort


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[minimo]

She’s alive!


Got a first ride around yesterday afternoon and she ran like crap which was sort of expected. There was some sputtering and loss of power going on which I’m going to guess are all carb related. I think I’m running stock jets in spite of the pod filters and an Outex (Japan) 4-into-1 exhaust with silencer muffler. My guess is that with a setup like this it’s gotta be running lean on fuel so it’s either an up size on the main jets or I was thinking maybe it’d be worth a shot to raise the needles (lower the clips) a notch...

I’m not accustomed to riding with clip-ons and I quickly realized that since the seat has the custom pan and padding that sits me higher, there’s an aggressive forward leaning posture that I’ll have to try and get used to. We’ll see how longer distances treat these old bones of mine.


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[minimo]

Stepping back a bit to look over these photos, I'm feeling better about the way the rear of the seat is shaped but I need to rework the front where the seat butts up to the tank - the crotch area. From the side perspective, the slant coming down from the tank I'm ok with but like Strynboen suggests, I need to integrate the lines and the "sqvared form" of the tank a little better to make it a consistent theme. I'll shave down some more and try to build in some facets to the crotch padding. A compromise of form over crotch comfort, we shall see ;-)

[strynboen]

it have a good harmoni...its just the small Things now...dont thange too mutch..

the tank is a bit low at the front...hard to thange..can a paint job vith a Black horensontal line in the bottom of the tank klear that up...or is it just a cool line..

[minimo]

Thanks, strynboen.
The bike is still in the dry run stage with a lot of old parts on the bike before I strip it back down to frame for powder coat. The tank is only primered; that is not the finished paint. Though I’ve been getting a lot of comments on that primer look where it has an almost olive drab color that’s somewhat appealing.
There’s going to be a lot of black on black so I’m thinking to make it less nebulous, perhaps a pink tank with turquoise accents?

I tried taking her out for another spin under different air mix screw settings and still getting the same result of the engine bogging at acceleration. The Outex exhaust and muffler might be a little restrictive/constricting, I’m not sure. How do I find out? In any case my pod filters would make for a leaner fuel condition overall, I’d imagine. At any rate, I’m thinking I might have to clean up the carbs again and recheck everything - assess if I’m really running stock jets or not. Thinking I’d rather do that than to sacrifice a fresh set of spark plugs to chop. The current set of plugs that I’ve ran now show mixed signs of both black soot around the tip of the threads and a lean condition at the electrode. So, this isn’t the best measure of what’s going on.

All 4 plugs look like this so at least there’s consistency there


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[strynboen]

take a roll of tape..and restrikt the pods..just for a test..you vill be surpreised...i faund that i can close them up to 90% to get a good airmix vith stock  setup..on smaller 100-125-140 cc bikes like china monkeyes and cross machines..as my kids have fun vith..think the same vill be on a sohc

[minimo]

I’ve seen the tape trick around the pods. Isn’t that kind of the same as adjusting the choke partially?

I’m here with my lap dog and a Sapporo

So far I’m finding tiny bits of the L400 foam shavings in some of the carb parts and passages :-/ Gonna give this all a laboratory clean and Pop this sucker back in with a fresh set of spark plugs to attempt a chop test.

Also found that my OEM petcock is leaking at the turn knob. I have a feeling that I might not have put the tapered o-ring in the right way and now it’s all warped and not making a good seal. Any fun workarounds for this? It’s a steady drip drip drip, not in the funnest location.


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[minimo]

Inspection report on the carbs and they’re standard sized jets across all, folks. No mismatches and nothing too exciting:

75 MAIN
40 SLOW

However...

#1 carb, the pilot jet was loosely seated and the main had a speck of L400 foam stuck in the passage - from my recent seat shaping :-/

#2 also had some of that foam shaving crud around the mating surface of the emulsion tube and the main jet

#4 had a flake of L400 foam in the float valve seat

I decided to move the needle up (all clips 4th groove down from top - stock is 3rd from top). See if that helps with the throttle responsiveness.

I also made sure that the throttle body cut outs were all facing the choke valves.

I have the air fuel mix screws backed out one single turn from fully seated. Before I did this I also pulled each of those screws out to examine them and the tips were all nice and blunted.

I’ll burn the carbon off the current spark plugs just to try and get the bike to idle and get a carb sync. Once synched I’ll replace those spark plugs with new ones and attempt to perform a plug chop to see where we’re at. Hopefully, the clean out of the carbs will fix the bogging issues. I’m very curious to also see what the needle raise will do to the system (should affect the 1/8 throttle opening).



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[strynboen]

yes it are just a choke..and kill all pontesionel gains..it vas just a test.idea to get a fun test ride..before go for bigger jets...