Topic: IDK Numero Dos - 1975 Honda CB400F

[minimo]

Thanks, strynboen. Will keep you posted this week when I give it another go.

Meanwhile, here’s a little before and now glimpse:




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[minimo]

Got her running and she purrs - no more sputtering.

Here’s the gist of it:

40 slow jet (stock)
88 main jet (75 is stock)
Needle clip 4th from the top - raised the needle; a richer condition
Swapped out oldskool points to a Dynatek electronic ignition. So smooth.

And that was pretty much it.
Oh, I uncovered a bad o-ring on one of the float valve seats per Strynboen’s clever “dry method” of measuring float heights using air as a substitute for fuel. I love this method and it gets you close to the right levels without the mess and stink of gasoline. Luckily I had a replacement o-ring and that took care of the float valve seat leak.

I never thought I’d say this but the bike runs too smooth - I want it to have a little more grunt so I’ll be taking the silencer baffle out. Oh, it’s zippy, no doubt about it, throttle is very responsive, but it kinda feels like a moped to me. I’m 5’9” and the bike might be a little on the small-ish size and with the seat trimmed down a bit, I can’t help but feel kinda like a grizzly riding a mini bike. I’d rather have it lean more towards me riding a rabid grizzly.

But there we have it. I still have loads in store for this project. Next step is to get it registered with DMV, I guess. After which I’ll have to strip it all down again to get it powdercoated. Replacing wheel bearings and spokes, tubes/tires, fork seals and oil, new rear shocks and bushings, new coils (Dynatek, of course), a fresh coat of paint on the tank, etc etc. The journey is almost complete but not yet.

More to come yet.
Thanks, y’all!


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[strynboen]

does it look like this:::.

..the only bike i ever fit real good ..vas my cbx 1000..all other bikes is to low and i cant have my" 47" shoes toes..at the shifter..so have to fight a bit to thange gears..

and yes the 400 is a bit to small and powerless..for real daily riding...but nice for sekkund bike. 550 is a more universel bike..can do the most..but still the 400 is the most cool looking Honda ever

[minimo]

Haha! That pic pretty much sums up how I feel on this 400F. But maybe it’s still too soon to speak so ill of this bike, especially before I get the rest of the gear on like shocks and new tires... hope that all makes a difference and an enjoyable ride.

So far, of all the classic Honda’s I’ve had a chance to ride, a 1975 360T has probably been the most enjoyable.


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[strynboen]

i had a  cb 500t..hated the bike from first ride..first ride on a four or six..the smootnes and fast rpm  vitaut the shaking..make that 2 cyll lokomotives  a rouf ride-..but 500 is probly a bit to big for tvins.the old tvins stayed the same in the 70...the fours got all the new parts..så late in 78..all Honda tvins got nev engines..but vent to be the most boring bikes ever..

 the older 350 and 360..vas fine small tvins..vho vas nice to ride

[minimo]

I love the steady putt-putt of the 360 twins. And it’s comfortable too and fun.

Meanwhile, took the 400F out again this late AM. Exhaust was popping on deceleration (I had the screw backed out 1.5 turns so I made it even across at 1 turn out. That took care of the popping but now I’m noticing a short lag at about 1/4 throttle. Maybe I need larger jets? 90 mains, maybe? Keep fiddling with AF mix screw?


On this short ride around, I had a few encounters from enthusiasts and they all loved the tank color - I kinda dig it too. It’s a Rustoleum Self-Etching Primer. It almost looks like a pewter gray/green so I may look into getting an automotive top coat in this same color.

I want to break up the void of complete darkness around the engine area. Right now, it’s just black on black on top of more black; it needs more specks of contrast. Thinking I can replace all the screws to zinc-plated socket cap screws on the engine sides just so there’s a little more variation with the color scheme.
The chrome on my rims is in ok condition. There are spots of rust in areas - I was thinking about going dark on the rims too as well as the hubs; the spokes will all be a zinc-plated color. Will a bead blast be enough to prep a chrome surface on the rims to take a powdercoat? Do I have to remove the chrome completely in something like a lye bath?
I’m also thinking about how I’m going to mount my license plate. In California, I read that it is “illegal” to have plates mounted vertically and to one side of the bike which makes it less visible from the other side... So, I was thinking about fabricating some type of bobbed fender to mount just beyond the underside of the rear hoop. I’m on the fence about this because the rear is what I like most about this bike and adding a bobbed tail would take away from the rear appeal. Any ideas?



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[minimo]

So now that I've installed a fresh electronic ignition and coils, all Dynatek, should I beef up my spark plugs?
Seems to work fine with NGK D8EA (stock) but just curious if there's anything

[minimo]

I couldn’t tell if it was smoke coming from my Bridgestones or from the Shorai...


I think I should address some clearance issues.


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[strynboen]

yes go for a 16" or 17"..think it vill straiten the bike..and give a better horensontal line..so you not need to ride head dovn..all time..it vill make the stering a bit slower..have no idea od a fat bubber tire vill look bad or cool..or you vill go vith a 3,50..

[minimo]

Thanks, calj737 and strynboen.

I'm going to try and figure out a new location and mount for the battery which also means that I'll have to at least modify the fiberglass seat pan. If this fails maybe then I'll consider going a size smaller or more on the rear wheel. I love the way the bike steers as it is and changing the rear wheel will take that away.

For the battery relocation, I'm hoping to push the placement forward about 2 inches but it would mean having to trim part of the stamped bracket that bridges the top just behind the tray. This forward placement should settle the clearance issue but I'm still apprehensive. Before I cut into that part, of course I will have to reinforce the frame in another spot probably toward the rear closer to the hoop.

[minimo]

I wanted to capture the essence of failure tonight in this photo. New issues arise after addressing others and right now, I feel defeated in an apparent cycle of woe. Sure, there’ve been highs and lows throughout this build, but tonight, after some succession of tackling issue after issue following a repositioning of the battery for rear wheel clearance, electrical problems now just don’t seem to cease. I’m exhausted.

The issues now:

1) The damaged battery is definitely giving up - can’t hold a charge as voltage depletes fairly rapidly even when nothing is connected. Off to disposal.

2) Voltage doesn’t rise when revving the throttle up to 2-3k . While I had the bike running idle and adjusting the carbs, the voltage eventually fell below 10V which is apparently detrimental to these LiFePo batteries. Signs are pointing to a possibly fried/damaged regulator/rectifier (this after accidentally crossing Pos/GND wires at the battery melting some of the wire housing and who knows what on the inside of the reg/rec. Doh!). Any good links on how to test a reg/rec?

3) Koso TNT-02 tachometer needle only moves, or rather sweeps on high throttle revs. It used to work perfectly before the battery relocation. I’ve gone through most of the pulse settings on the gauge and nothing yet seems to work as it used to and should. Any ideas?

Repositioning the battery meant reworking the seat pan and figuring out how it mounts. After much cutting and grinding, some welding, and reapplying of fiberglass the seat it at a point now where it might be good enough for some highway riding.

I want to get this bike on the road again to make sure that the battery reposition is ok (even though I tested for clearance by raising the rear wheel sans suspension). There’s also now a goal set for this build since I made an appointment to start the registration process at the DMV on June 11. So I’m under a bit of a time crunch.

Though there are problems that come up from time to time, I’m confident that these are all fixable issues. Beside, this bike was running fine before. Tonight’s fail will make the first good ride a big win.

Good night.

[SOHC4 Cafe Racer Fan]

It sounds like that battery had its last charge.  You are correct that when they drop below a threshold voltage they do not recover.  I've lost 2 that way.

[minimo]

It’s good to know I’m not the only one trashing these batteries. Thanks, Cafe Racer Fan!

Thanks for the notes, calj. I will work on those points and get back soon.
On the Dynatek coils, since there’s no polarity for those wires, is there a preference on which wire to connect to; upper or lower? On the Koso, it has the ability to switch between “Hi” (positive) and “Low” (negative). I suppose I can switch around with it when I get to it. I’ll look at the respective instructions on both the Koso and the Dynatek.

Funny, I had the rpm wire connected to one of the yellow sensing wires on one of the connectors in my rat’s nest and that was working before the battery issue...

Ughs




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[minimo]

Last night was a complete failure, but tonight was a nice turn of events.

I could have kept riding tonight; the bike is zippy and so much fun to ride. But I feel like I owe it to some of you to report back so here's the breakdown:

1) RPM wire connected to Yellow (bottom) wire on Dyna coil 1-4. Bingo. I found that the Koso setting to P-1 gave the best and most accurate tachometer reading. I thought it should be on P-4 (4 pistons, right?) but P-1 it is.

2) Thanks for the ElectroSport link with the chart, calj. I totally forgot about that. I followed it along, setting the multimeter here and there per the instructions and it finally led to the 12V ignition as a possible culprit. Checked it out and some wires easily came undone and it appeared that Brown/White was disconnected completely. But Brown/White isn't associated with charging (more running and gauge lights etc) so I dug a little deeper. It had to be with the charging wires and where haven't I check out yet, I thought. The left side cover. And lo and behold, 2 of the 3 Yellow wires were disconnected! So I pinched the female connectors to make a snug fit and reconnected those Yellows and started her back up and just like that, we have charge, folks. It was just a relief to finally see the voltage climb up from 12.6 to 13.3 and up as I steadily rev'd the bike, watching as the tach needle gave its appropriate readings. So battery charging - check!

3) Battery relocation is seemingly a success too! After a pretty hard ride around the neighborhood with bumps abound, I see no sign of burning rubber on the battery nor elsewhere. We have complete rear clearance of the rear tire and under carriage.

So there we have it. Win, win, and win. Now I might have to get to a little bit of tuning straightened out as the spark plugs appeared a bit on the lean side so hopefully that just means a slight turn in on the air mix screw...

This bike kicks butt.

Thanks again, y'all!

[minimo]

They outta be shaking, calj. There are so many cool builds going around and hardly any cool bikes coming out of manufacturers these days. I don’t know, are there any compelling bikes out on the market right now worth gawking at? I wouldn’t mind running a few laps on a 2018 Kawasaki Ninja H2R though
https://m.kawasaki.com/product/details/2018-Ninja-H2R

Took this 400F out for a quick ride around tonight. She can run a lot better, I think.
I have the air mix screws 1 turn out from seated. Noticing a bit of smoke coming out of exhaust at idle; more smoke than I am comfortable with. At about 1/4 throttle (and 3000-3500 rpm) in 1st gear, there’s a bit of a stumble. After running a straightaway at WOT, plug chopped, it looks to be on the pale side of a lean condition. Should I try raising the needle one more notch? Needle clips are currently 4th from the top.
Midrange is perfection so I won’t be messing with the main jets (currently at size 88).
Idle jet is 40. I’ve read of some people downsizing?


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[minimo]

Yes, I dig those Kineo wheels.
https://www.bikehps.com/kineo/

As for the smoke coming out of my 400F, I'm scratching my chin...
The smoke, I think should be well beyond the condensation/vapor stage especially after last night's ride of over 3 miles. The whiffs I get are evident of smoke, almost like burning oil, maybe it's fuel - light turns green too fast for me to be sure (unless it's from the cars around me when I'm at idle). Fuel smoke would point to a RICH condition, right? But if that were the case, then why are my plugs looking lean? But for reading how the bike is running, I would take how my plugs are looking over just how smokey my exhaust gets.

I'll start tomorrow first thing by doing a complete cam chain, valve and ignition timing adjustment respectively and go from there.

Have a nice weekend, y'all!

[minimo]

Thanks, calj. I’ll get around to doing a plug chop on some fresh plugs - or run the bike on a dyno, whichever comes first. Or both.

A rare rainy LA morning. A good excuse to hang indoors and tidy up some wiring in this rat’s nest under the seat and perhaps a raising of the carb needles...


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[minimo]

Surprise-surprise... so it turns out I had installed an old ElectroSport ESR240 3-phase reg/rec and I was getting a zero reading on the Reverse Bias: Bottom 3 Diodes - Test 2 which probably isn't good - hoping this wasn't from any damage that it may have incurred from my inadvertently switching pos/neg leads on the battery.
Anyway, this ElectroSport reg/rec was an old one I had previously tried installing on my 550F and was having problems with and ended up getting a Rick's and have had no problems since. I later came across some notes that the ElectroSports don't work with lithium batteries as even 4into1.com has this disclaimer to mention that:

*Note: This is not designed to work with Lithium batteries. It does work with all standard lead-acid based batteries which came stock on the models below. It also works with AGM, Gel and other sealed batteries.

I also read that ElectroSport has updated their ESR240 to now work with lithium batteries but I'm certainly not going to take that chance of trying again since I've been having good working results on my 550F with a Rick's reg/rec connected to a Shorai LFX14A2-BS12 LiFePo.

[minimo]

Does anyone know if these would work on my ‘75 400F?

https://www.mikesxs.net/yamaha-xs650-h-2-15-x-18-x-36-hole-shouldered-aluminum-rim-black.html

H 2.15x18 36 hole shouldered aluminum rim BlackHard to find. Works with XS650, XS400 36 spoke hubs. Classic 36 spoke pattern works with other vintage bikes but we cannot guarantee which. This is a quality rim comparable to what you see on other sites for much more money.Dot approved.Great for chopper, bobber and rat projects. We put this rim on the front and back of our company XS400 Cafe project - they look great.Note: our spoke set 19-0049 works on the rear for the XS400, 19-0050 on the front.

I’m intending to use them on both front/rear. The great thing is that they already come painted black (even better if they’re powdercoated) so I don’t have to powder coat my old ones.


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[minimo]

36 hole hubs and 36 hole rims. But, the angle of the spoke may be off ever so slightly, and the nipple size may need to be ordered special (you could consult Buchanan's for those). But in theory, they should be compatible with your hubs.

Thanks, calj! So fast - love it!

I ordered a zinc plated set from 4into1.com
Would I need to order a Buchanan special set to replace those then?


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[MoMo]

rims are wider than stock, FWTW...Larry

[minimo]

36 hole hubs and 36 hole rims. But, the angle of the spoke may be off ever so slightly, and the nipple size may need to be ordered special (you could consult Buchanan's for those). But in theory, they should be compatible with your hubs.

I will check with Mike's on the spoke/nipple sizes.
If this isn't a good fit, maybe powdercoat will be the way to go.

[minimo]

rims are wider than stock, FWTW...Larry

Thanks for catching that, Larry.
Mike's does have a 1.85-18 option also which is equivalent to the 400F stock rear.
https://www.mikesxs.net/yamaha-xs650-h-1-85-x-18-x-36-hole-shouldered-aluminum-rim-black.html
These are also aluminum rims so I will assume, since I've yet to hear back, that these might be anodized black; not painted, not powdercoated.

[MoMo]

rims are wider than stock, FWTW...Larry

Thanks for catching that, Larry.
Mike's does have a 1.85-18 option also which is equivalent to the 400F stock rear.
https://www.mikesxs.net/yamaha-xs650-h-1-85-x-18-x-36-hole-shouldered-aluminum-rim-black.html
These are also aluminum rims so I will assume, since I've yet to hear back, that these might be anodized black; not painted, not powdercoated.

Glad to be of assistance.    Those rims are a nice look and reasonably priced to boot.. Good luck with the build...Larry

[strynboen]

you already have a 18 at the back...so no ekstra free.. under the seat..have yoy freed up the battery space