Topic: IDK Numero Dos - 1975 Honda CB400F

[minimo]

Loose bolt on the sekundery shaft..eating the cover...had one before...just weld the hole--and teight the bolt...and get a new Lock plate behind the bolt..as i renember..long time been there

Thanks, strynboen. Yeah, I must not have tightened that bolt down. Damnit.
This is the assembly that has that one thick washer that has imprinted “OUTSIDE” on it, I believe.

Meanwhile, looking fwd to inspecting the shift fork dogs. Forthcoming...

I am going to conquer this bike!


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[minimo]

Always tighten down your hardware

Secondary drive gear, corresponding bolt, “OUT SIDE”-labeled washer, and clutch basket and all surroundings so far look unscathed and fine considering the damage.

I’m going to see about getting this cover repaired

Maybe too far gone?



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[minimo]

Loose bolt on the sekundery shaft.(or is it the primar shaft)....eating the cover...had one before...just weld the hole--and teight the bolt...and get a new Lock plate behind the bolt..as i renember..long time been there

And yes, it is labeled as the Secondary Gear on the Primary Shaft.
I’ll need your eyes to inspect the dogs on my shifter forks, when I can get to them.


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[minimo]

So, WHAT IF somehow one of the 20mm thrust washers was missing from the gear assembly, say the one on the outer side of the COUNTERSHAFT LOW GEAR COMP, part number 253 pictures here:

Now, this would be a just a hunch but would not having this washer make 1st gear not work so great?


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[minimo]

Bike is back together and rolling around like thunder. I’ll confirm that it was the thrust washer (or lack thereof) that was giving me those issues with first gear clunking. Not having it there was enough to give it slop and allow it to knick some other gear that it’s not intended to, I guess. The golden rule: make sure these engine parts are accounted for and also be sure to tighten down everything. Luckily, there was no great damage to my shift forks, only some scuff marks. Measured the dogs and for straightness and all seemed within spec. Shifting now with the thrust washer in place sandwiching that top gear makes it all smooth-smooth-smooth. Funny that I’m still kinda cautious getting into 1st gear - real 1st gear trauma.

Other than some light tweaking around, air fuel mix screw adjustments, and a carb synch, I’m pretty pleased with the bike for the moment. Maybe soon I’ll paint the tank and get the seat upholstered.


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[minimo]

Oh, and a friend made an attempt to weld that clutch cover but there were some pin holes that let fluid through so rather than smothering a bunch of Hondabond all over the inside to seal it I just opted for a replacement part and all is well.


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[minimo]

I purchased and stuck on that special center stand from AGAIN - it has a cutout to dodge the muffler. Fit like it was meant to be there. Love it.



https://japan.webike.net/products/21955641.html

Meanwhile, bike is running a little crap at the moment - just getting back to riding after some months of being away. Blubbery at high RPM and bike bogs down after riding some duration at speeds of up to 75mph. It’s the carbs.

Just finished a carb rebuild replacing the aftermarket needles and emulsion tubes back to OEM to see if that might make it right. Also downsized the jets from 90 to 85 (75 is stock) and maintained the needle clip at 4th from the top (3rd from top is stock) - a recommendation from harisuluv (is he still around rebuilding carbs and making seat hoops?) and he said “works quite well”. Pilot jet is 40 stock. See how this set up goes in the AM.

Next day after this rebuild:
So far so good - the best this bike has been running in a long time. Testing the rides out on surface and seems steady so far. Will take to highway for a more longer and faster ride.

This is what I’ve been missing - chasing issues is what the fun is mostly about


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[strynboen]

its  fun ...as long the bike gets better.

..one step forvard...and 2 back..can kill the road fun.

.but seems you have get over the vorst problems..and just need fine tuning now...

need to find a battery for my 400..it have not be driven this seson...so have lost all power..just like mee...hope to get a few road  rides this summer..the 550 stays ready..its the most relibel bike..can stay for monbths,,and fires just up..and is ready..

[minimo]

These bikes are just like us, strynboen. I agree!

Let’s get some great rides in this summer!




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[Rick4004]

Just finished a carb rebuild replacing the aftermarket needles and emulsion tubes back to OEM to see if that might make it right. Also downsized the jets from 90 to 85 (75 is stock) and maintained the needle clip at 4th from the top (3rd from top is stock)

You are probably too rich all thru the rev range. The 400's run better with 38 pilots when using pod filters, and I've never had to change the needles from the stock position. 85 or 90 is probably about right for the mains. I haven't read your build, but aftermarket coils make a big difference too. The stock coils are crap.

[minimo]

Keepin it cool and hearty



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[minimo]

Well, while I had the cases split apart again, I figured I’d replace some “while I’m in there” parts.

Guess which one’s the used primary drive chain?




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[minimo]

I hope everyone is out enjoying the rides and doing well, keeping warm.

This happened today:

Crusty welds (by a previous owner).
Nearly laid the bike down.


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[RAFster122s]

Minima, that bites…hope you still have a center stand…

[desertrefugee]

... I hope that doesn't mean the bike hit the ground

[minimo]

Center stand is intact. I muscled the bike up, so I lucked out.

I got a great center stand from Again (Osaka, Japan). It dodges the header




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[strynboen]

have sold my 550,,so only have the 400 four..it runs..but need a total rebuild..all thains and crank bearings..need to be thanged..and the camis veared..dirty oil..and 85,000km have done the job

great that you still are on forum...

[minimo]

Looks clean, strynboen.
We’ll, you know that you can access the lower crank case from the bottom. Easy-peasy

Enjoying the rides on my 400. Maybe someday soon I will get the seat upholstered and the tank finally painted. Maybe then I will consider to finally sell the bike.
2022 will be the year that I get moving on a classic Ducati single rebuild. The fun never ends.


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[minimo]

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[wolf550]

that is what I will be doing in the near future with these three carb sets.
going to see what is good on each set and make a good set.

[minimo]

I want to point out that Honda makes the best rubber parts (move over Trojan, Sagami, and Okamoto). The Main Jet O-ring pictured above and two others like it came out sheared or peeled while investigating a rich fuel condition following a recent carb clean/rebuild. I replaced the O-rings with some fresh McMaster-Carr ordered Buna-N O-rings. These Main Jets, btw are not Keihin as I'm running airpods and have to upsize my mains. I have another set of aftermarket mains with Honda O-rings on them, and I'm going to see if these will do the trick.


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[grcamna2]

subscribed

[minimo]

Long story short, I ended up fitting my carbs with FKM (Viton) O-rings purchased from www.oringsandmore.com (fast shipping, btw). So far, so good.

The long story… I thought I’d try Velocity Stacks to replace the cheapo pods I had installed for a long time. I think the velocity stacks look nice but not practical for riding, and I would later find a challenge to tune. So this resulted in me cleaning my carbs, giving all parts an ultrasonic wash, poking around with musical wire, and the whole bit. I spent a good chunk of time cleaning and replaced the old O-rings with Buna-N O-rings that turned out to be crap and peeled after one install attempt. The bad O-rings sent me down a rabbit hole trying to find out what was giving me rich/sputtering issues - learning later that the sheared Buna-N O-rings created an opening for fuel to wick past the float valve seats and the mains. Since replacing these Buna-N O-rings with FKM (Viton) o-rings with the exact dimensions and replacing the v stacks with cleaned-up airpods, the combo seemed to fix all of the issues.

Current set up with airpods:

FLOAT LEVEL: 21.0mm
SLOW JET: 40 aftermarket (stock: 40)
MAIN JET: 90 aftermarket (stock: 75)
NEEDLE & CLIP: 4th (stock: 3rd from top)
IDLE MIX SCREW: 1.5 (2 turns from closed, stock). 2 pops on decel

Still kinda fiddling - might move up to 98 mains and back up to 3rd from top needle position - but current setup is pretty darn responsive from idle up to mid-throttle. Never fast enough at WOT, but maybe this is good enough for now. See y’all down the road.



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[minimo]

Sharing a recent part/assembly upgrade - front brake.

This is a Brembo front brake kit supplied by Again (Osaka, Japan). It came with the Brembo brake, perforated disc, a custom CNC mounting arm/bracket and a brake line and banjo bolts (10mm x 1.0), bolts, nuts, offset plates, etc. Easy install. So far, on the road, I think I get at least double the braking power compared to the stock setup I had on previously.

I’ve got a separate Goodridge kit coming soon to swap out the current lines and banjos.

https://mc-again.com/cgi/parts.cgi

$670USD was a bit of a stretch, but hey, I work hard to keep my motorcycle happy.

Meanwhile, my fuel tank remains primer’d and unfinished.



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[MauiK3]

Cool brake setup.