A 1975 CB400F high mileage complete engine rebuild

[jensen]

Cleaned all small parts and ready for plating (Originally cadmium yellow, but since cadmium is forbidden, a more silver gold finish will be the result) :

 

[ballbearian]

Did you have any or many of the extinct 5mmx0.9 screws?

 

[LongDistanceRider]

Your Tikopour is actually cheaper than the LPS Precision Clean I use, looks like good stuff.
The lower the Hz the better with the ultrasonic units. Most of the cheaper ones here are running 40Hz, my current one will do 26Hz or 40Hz plus has a Degas function. 60-70C seems to be a good temp.

 

[jensen]

The lower the Hz the better with the ultrasonic units. Most of the cheaper ones here are running 40Hz, my current one will do 26Hz or 40Hz plus has a Degas function. 60-70C seems to be a good temp.

Yes, indeed, the lower the frequency, the better it gets. However, for small holes and tiny galleries, the 40 kHz is a better choice.

 

[jensen]

After cleaning my carbs, I finally could go further with the CB400f. I installed the battery, side covers, did some wiring and replaced the rear break shoes.







Next week a busy week, so hopefully next weekend putting the carbs and air box in.

 

[stl360+450]

Next week a busy week, so hopefully next weekend putting the carbs and air box in.

Getting close! What is the weather like there at this time of year? I guess it will still be decent enough to ride when it's ready for the maiden voyage?

 

[jensen]

The weather is nice, perfect for a ride on my CB450, unfortunately not on the CB400f. Getting close, but not enough for a maiden voyage this season, I guess. Work gets in the way, so time in the shed is limited. There are a few open ends that consumes time, re-chroming the rear fender is one of them among others. Next to that, since it's insured as an old-timer, I'm not aloud to ride the bike between 1st of December until the 1st of March. Next year I will insure the bike as a non-old-timer, it's more expensive, but it will be my man source of transport next to the car, and that makes the CB400f a daily rider instead of the CB450 K0. The CB450 K2 (when ready) will be the daily rider for 2024, or a combination with the CB400f next year if things go a little faster. The K2 is an easy resto, only the engine has to be done, the rest is in perfect condition, and paintwork is one.

 

[LongDistanceRider]

Yes, indeed, the lower the frequency, the better it gets. However, for small holes and tiny galleries, the 40 kHz is a better choice.

My new unit has 26 and 40 so I hit carbs with the 26 first and then 40.

 

[jensen]

There are times that I wished I worked on a twin. What a f.... job to get those carbs between airbox and cylinder head. After trying a few different methods, I went for the strap-band. Works, however, one evening futher and the only thing done is to install the carbs, Took 3 hours in total...








Tomorrow the inner tire trick.......

 

[ballbearian]

Great strap trick. I hope your shop is toasty warm, that seems to be a big help for me (and why I have an old hair dryer around), when it comes to messaging rubber and plastic. I have only one four banger, that's enough.

 

[Flyin900]

If it was an issue with getting the carbs into the front new insulators the strap is a good method. Since the clearance between the front and rear insulators is tight too. I have found it is best to push back the rubber oval tube on the rear of the air box into the metal box that contains the air filter. You need to release the inner metal sleeve inside the oval rubber in the metal air filter box. It gains you the much needed extra inch of space to work in there and then you can reattach the oval tube into the rear of the air box.
I just did a CB350F which uses the identical set up and it went quite quickly and smoothly, yet I have struggled like you in the past with that same issue. Since I have restored about 6 total of the CB350F and CB400F models I look for tricks to help ease the pain.

 

[jensen]

Before the first picture, I used the strap band to push the air filter box as close as possible to the frame. Creating space this way, I did put the carbs between the air box and intake rubbers. Once in place (but not yet in position in the intake rubbers, I took the band off the air box and put the band as in the first picture. With help of the strap band, mineral jelly and a heat gun (to heat up the rubbers) I finally got the carbs into the rubbers.

To get the air box rubber seated I will put a inner bicycle tire in the box and pump it up, this way I force the rubbers of carb 2 and 3 in places, as well as the oval rubber connection to the air filter housing.

Hopefully I don't have to take the carbs out again.....

 

[Flyin900]

I like that rubber bicycle tube method as the two inner air box rubbers are always tough. The hardest I have found are the 1980's CB900C or CB1000C for those inner two on the air box. Virtually zero room in there with the various breather tubes and the starter motor cover on the left side top of the motor. Next time I have to do a set of those carbs I will give that bicycle tube a try on getting those to stay in place.

 

[Maraakate]

Hi Jensen,

I just want to say yet again I really appreciate your attention to detail and trying to do things as right as you possibly can. Not to derail your thread, but I'm in the middle of trying to rebuild a Puch Maxi E50 Moped and have been getting a lot of laughs, criticism, and shortcut advice when I just want to make it original as much as I can do/afford. Very few people seem to appreciate getting things back to the way they were the day it rolled off the assembly line. Again, amazing work and I'm sure you've been through similar uphill battles.

 

[ballbearian]

Hi Jensen,

I just want to say yet again I really appreciate your attention to detail and trying to do things as right as you possibly can. Not to derail your thread, but I'm in the middle of trying to rebuild a Puch Maxi E50 Moped and have been getting a lot of laughs, criticism, and shortcut advice when I just want to make it original as much as I can do/afford. Very few people seem to appreciate getting things back to the way they were the day it rolled off the assembly line. Again, amazing work and I'm sure you've been through similar uphill battles.

I just PM'd you, Frank.

 

[jensen]

Hi,

A Puch maxi E50 was my first moped (I was 16 years old), that brought me every week from Hilversum (where my parents lived) to Leiden (where I studied), on Monday morning and Friday afternoon, with my school stuff and laundry. A very reliable 2-stroke moped, never had any problems with it. I remember it was white, with spoke wheels, and good fuel economics too (as a student you care....) 55 kilometers one-way, even in winter. A very popular moped in the Netherlands, still lots of parts available here. If you need any help in shipping parts, just ask. Do you know this place ? : https://puchonderdelenrijswijk.nl, website is only in Dutch.

 

[Maraakate]

Hi,

A Puch maxi E50 was my first moped (I was 16 years old), that brought me every week from Hilversum (where my parents lived) to Leiden (where I studied), on Monday morning and Friday afternoon, with my school stuff and laundry. A very reliable 2-stroke moped, never had any problems with it. I remember it was white, with spoke wheels, and good fuel economics too (as a student you care....) 55 kilometers one-way, even in winter. A very popular moped in the Netherlands, still lots of parts available here. If you need any help in shipping parts, just ask. Do you know this place ? : https://puchonderdelenrijswijk.nl, website is only in Dutch.

E50 is pretty solid engine. I prefer the Sachs 505 series. I think they're even easier to work on and give out better performance. The biggest flaw on the Sachs is that the head and cylinder are one unit so if you seize it then it's total junk.

Never been there, but will check it out. I've put about 8000 miles myself personally on my Maxi. It's very tired now. Ring gap is 4 times over the spec and con rod has significant play on the big end bearing so new crank time. Have a friend who can bore out the cylinder for me to make it right. Only problem is most maxi's had aluminum cylinders that are plated. The "hi torque" series cylinders are cast iron sleeves and can be bored. Working on sourcing a used "hi torque" cylinder for this project. Finding NOS puch oversize pistons for it are near impossible, at least here in the US and on eBay so your site may be where to find it. If that fails I plan on using an aftermarket Meteor piston from Italy that is 38.50mm/+0.50mm oversize.

But, I feel you have probably been down this road... I asked locally where to go and a lot of people laugh and say "just put a kit on it, they make 50cc kits". I refuse to do this because the kits are NOT the same quality as the OEM. They also have changed porting. What happens is you lose a lot of low end torque and it's traded for ~10mph faster top end. I am uninterested in playing with gearing ratios and clutch springs to "fix" the problem. I know it's a moped, and it's not a high value bike but I value it as it's my first moped as well and I also value keeping things original as much as you possibly can. I've bet you have asked around for help/advice and have gotten laughs and been told to take shortcuts because it's cheaper and "mostly the same". You and I both know that it is not, and I really respect the level you go to. Very few people do, and even fewer seem to appreciate it. But, there's a sense of satisfaction knowing it's right and you don't have to question if the kit is bad, or some crappy aftermarket part failing on you when you try to take it out and ride it. Life's too short for cheap, crappy parts.

Anyways, don't want to derail your thread and your progress. Looking forward to seeing the first start up and you're doing an amazing job!

 

[jensen]

Anyways, don't want to derail your thread and your progress. Looking forward to seeing the first start up and you're doing an amazing job!

No problem, and thanks for your admiration, so lets move forward....

Since you all know I'm having a "slight" characteristic disorder called OCD. On most jobes at the bike this is easy to handle, but when it comes to wiring and tubing / routing / positioning, it's getting really nasty. Last few days it was routing tubes, tonight it was cabling. I can be busy for hours to get it right, but when finished, it's sometimes better then Honda I'd say.

 

[Maraakate]

Yes, cable and hose routing can be tough. Especially when the book isn't very clear or some of it is only a sticker and even then it may not be 100% obvious.

For me, personally, there's a point I reach where enough is enough. I tend to go an extra mile compared to an average person, but I won't do it over multiple times all evening for the absolute perfection. I salute you on that, there's just a point where I run out of patience and it's not harming anything so I let it be and move on to the next task.

 

[jensen]

but I won't do it over multiple times all evening for the absolute perfection

Two evenings where needed to reach the structure out of chaos...., yes OCD struck again..


Since I like to have my Garmin and probably an USB contact on board, and want the power to be switched, I made an extra wire to do just that.



Find some old wire harness parts and cut to length



crimp bushing



ready for crimping



correct tool



crimped wire



cover with crimp shielding and glue




Now I have two extra switched power lines directly from the main harness.

 

[ballbearian]

I can be busy for hours to get it right, but when finished, it's sometimes better then Honda I'd say.

Often talents or gifts are called a disease. Your careful efforts are much appreciated and wonderfully compounded by your ability to communicate, both verbally and visually. Definitely giving Honda's execution a run for it's money.

 

[ballbearian]

An apt use of the term, plug and play, I think.

 

[jensen]

Often talents or gifts are called a disease. Your careful efforts are much appreciated and wonderfully compounded by your ability to communicate, both verbally and visually. Definitely giving Honda's execution a run for it's money.

Don't know about that, but sometimes I wonder why things are done in a certain way, and saving time and costs in production is mostly what I can see as a reason.



Mounted the headlight as last electrical part, ready for testing.



Putting the key in and switch it on is a magic moment, will everything work, one time right ?



And after switching on, oil indicator and neutral indicator work.



Next step is to switch the lights on to city light, gauge illumination works too.



Then the headlight, no problem there either



And last but not least high beam, works too.


Signal lights, horn, break switches all work too. The next step is too start the engine and see if the battery is charged while running, but that will take a while before I'm there. I also need to wire the Garmin and an USB connector to it, will do next week or so.

So far so good, everything (battery fed) works, so another milestone reached.

 

[jensen]

Filling in the open ends and small stuff.



One of the last cable routing tasks I had to do after ordering the rubber band to hold the wiring in place




All the parts for the air filter cleaned and re-plated. I did put new filter paper on the re-plated filter. The piece of foam is from 1974 too.




Mounted and tested





Front sprocket 16T mounted, instead of 17T only for the first 2000 km or so.




Cleaned the rear mud flap with original 1974 stickers and phone number of the shop where this bike is bought.



This is the shop, which closed it's doors in 2013 after being 43 years in business.

 

[ancientdad]

It's always nice to save the selling dealer's sticker when it's still on the bike. My CB350K1 still has the selling dealer sticker on it and I'll be doing my best to clean up the rear fender while keeping it. You should be close to starting the engine for the first time.

 

[jensen]

Yes, that dealer sticker and the NL sticker (mandatory in those days) are the cherry's on the cake. I'm waiting for the rear mudguard (still at the plater). I will mount the fuel tank and mufflers soon, and then I can start the engine the first time. Unfortunately I have to wait until spring next year to ride it, but I'm patient. The bike has to leave the lift, so the next bike can be build up. Don't know jet which bike that will be, I can choose between a CB72'62, a CB72'67 or a C77'64 The build of the four twins takes place in an other location. At home I have only room for one bike at the time, since the garage is very tiny as you saw in the pictures in this thread.

 

[Maraakate]

Signal lights, horn, break switches all work too. The next step is too start the engine and see if the battery is charged while running, but that will take a while before I'm there. I also need to wire the Garmin and an USB connector to it, will do next week or so.

So far so good, everything (battery fed) works, so another milestone reached.

Looks good. I'm kind of surprised you kept the original gauges with the faded red. Do you plan on finding NOS or are you opposed to getting reproduction faces, chrome ring, etc. from https://www.cb750faces.com/en/38-honda-cb400-four ? There's a lot of action in this thread, maybe you did this and I missed it but did you replace the rubber dampeners/holders for the instruments? They're usually rock hard and partially stuck onto the bracket and/or the instrument itself. Rubber grommets in that area are usually garbage too. I've done new dampeners and rubber grommets on my stuff, but it's not a huge priority and I waited until everything else was good before I spent the money.

 

[stl360+450]

The photo of the bike shop is a nice touch on the thread and well framed.

You mention using the 16T sprocket for the first 2000 km. Is the desire there to run slightly higher rpm during the break-in period?

 

[ballbearian]

Yes, that dealer sticker and the NL sticker (mandatory in those days) are the cherry's on the cake. I'm waiting for the rear mudguard (still at the plater). I will mount the fuel tank and mufflers soon, and then I can start the engine the first time. Unfortunately I have to wait until spring next year to ride it, but I'm patient. The bike has to leave the lift, so the next bike can be build up. Don't know jet which bike that will be, I can choose between a CB72'62, a CB72'67 or a C77'64 The build of the four twins takes place in an other location. At home I have only room for one bike at the time, since the garage is very tiny as you saw in the pictures in this thread.

The stickers and dealer shop photo are what is termed "provenance" (probably of French derivation), I believe. I've learned not to use harsh cleaning chemicals on old printed stickers and such, as well as original aged rubber and vinyl parts. I was given a partial bottle of a product used by scuba guys for preserving their wet suits and fins, etc. that seems to work well for cleaning and preserving.

Your filter media pleating is top drawer, better than the folded napkins at a 5 star restaurant .

 

[jensen]

Your filter media pleating is top drawer, better than the folded napkins at a 5 star restaurant

The folds where already in the paper since I cut a filter element for a car. It took a while to find the right glue, most glues are brown, but the original glue color for the CB400f is "white-isch."

Tonight I did clean the front mudguard, and made it ready to fit.



As clean as can be, no rust, no problems




Even the model code is stamped in the mudguard




And the same dealer sticker on the front mudguard.

I did spray a protection layer on the inner side of the mudguard after taking the above pictures, tomorrow it can be mounted.

 

[ballbearian]

Yes, that dealer sticker and the NL sticker (mandatory in those days) are the cherry's on the cake. I'm waiting for the rear mudguard (still at the plater). I will mount the fuel tank and mufflers soon, and then I can start the engine the first time. Unfortunately I have to wait until spring next year to ride it, but I'm patient. The bike has to leave the lift, so the next bike can be build up. Don't know jet which bike that will be, I can choose between a CB72'62, a CB72'67 or a C77'64 The build of the four twins takes place in an other location. At home I have only room for one bike at the time, since the garage is very tiny as you saw in the pictures in this thread.

My vote is for the Dream next. Either way, I'll be quite interested in how you contend with the advance unit on the 305 style motor, I assume the 250's have the same advancer. When the rubber return stops disintegrate it adds additional range (sort of) in degrees, causing difficulty in setting timing.

Do you also have terrazzo work bench tops at the other location?

 

[jensen]

I'll be quite interested in how you contend with the advance unit on the 305 style motor, I assume the 250's have the same advancer. When the rubber return stops disintegrate it adds additional range (sort of) in degrees, causing difficulty in setting timing.

I don't. I'll use another E-ignition from Sachse, it gets the timing from the crank and has an electronic advancer. I have very good experience with this setup on my '64, and will add this unit also on the '61/'62 bike. Expensive but worth the money. Here a link: https://www.elektronik-sachse.de/shopsystem-3/en/digital-ignition-zdg-3-23-for-honda-cb72-77.html

No, I will do the sub-assembly at home, and total configuration on an other location.

 

[teebo]

I don't. I'll use another E-ignition from Sachse, it gets the timing from the crank and has an electronic advancer. I have very good experience with this setup on my '64, and will add this unit also on the '61/'62 bike. Expensive but worth the money. Here a link: https://www.elektronik-sachse.de/shopsystem-3/en/digital-ignition-zdg-3-23-for-honda-cb72-77.html

No, I will do the sub-assembly at home, and total configuration on an other location.

Nice. They also have one for the 350 and another for the 450K. Do you happen to know if it works on the K0?

69 CB350K1/68 CB450K0

 

[jensen]

Sachse has a set for the 450, I have one set, it works, but I won't buy it for the builds of the four twins. The reason is that the original ignition system on the 250 / 305 is not really simple to adjust, and the timing is heavily influenced by chain slack. This causes irregular timing thus irregular running. Placing the pick-up at the crank is in fact the only reason for me to buy these sets for the 250 / 305's. The system from Sachse for the 450's is picking up the timing from the exhaust cam, the same as the original system. Since the 450 has a really long camchain, and lot's of slack, it leads to irregular timing too, so for me no USP.

 

[jensen]

Another day of small jobs, like cleaning, organizing and putting back some parts on the bike.



This is the tool tray, since I got this bike from an old man, who bought this bike new (first owner) and maintained it perfectly, the toolset is more then complete and altered.




Complete toolset, plus a few interesting modifications to the original tools.




Modified tools for adding more torque. The height of these loops will fit perfectly in the tool pocket. Hans (PO) was a craftsman, knowing what he wanted, and how.




The PO added a few extra's to the tool tray, all spare bulbs, a set of extra breaker points and a modified spark plus for cleaning the threads.




Out of respect and reverence for the passed away original owner (Hans was his name), I keep the things just as he handed the bike over to me (more information in the first post of this thread).




The cover is damaged, and still looking for a new one. However, difficult to find a good one.

 

[jensen]

Slowly moving to the end of this build. Still waiting for the re-plated (chromed) rear fender.



Some rust in the known spots, and after a warm bath in oxalic acid and some scrubbing, the exhaust was ready to bolt on. I have a original NOS set and an after market new set, but this original set will do for now. Some very small rust spots on the pipes, but it's from 1974.




Now it's starting to look like a bike




Very clever engineering, oil filter and sump still reachable with exhaust on the bike.




Catch of this week, a CB72 speedo, refurbished, exchanged for a CB125SS K1 speedo. This is a the correct speedo for my '62 bike in Km/Hr.

 

[jensen]

I added a coating of tectyl underneath the petrol tank, the same coating as underneath my mudguard.



With heating and making the tectyl fluid like water, it will fill all holes.



Both are re-united again after 12 years



This will be my view on the bike while riding it.

 

[ballbearian]

Visual four part harmony. Just beautiful.

 

[Maraakate]

Regarding the sealant under the tank... have you tested long term effects of this? I've been wary of using this or "chip guard" or "shmutz" as the body shop guys call it.

The main reason this kind of stuff has been discouraged in restorations in body shops is because they used to use this a lot on entire frames after prepping them. Then they found out about 15-20 years later this stuff seems to trap in any residual moisture and instead of rusting it simply rots out and falls off in chunks. There's been quite a few restorations I've been involved with on cars where they had these kinds of treatments sprayed on them in the 70s or 80s, then the car changed owners and a person wants to restore it again. We start disassembling and find things come off in chunks.

 

[jensen]

I use it mainly underneath a gastank and I never ran into problems with it. However, I know that this can be the case and I'm aware of it. Therefore I remove the layer every 5 years and respray, also for mudguards..

 

[jensen]

Preparing the bike for the first start after 12- 13 years. Flushing hot oil under pressure though all bearings via pressure sensor connection on top of the oil pump. Then remove the oil pan, clean it, build it back, remove oil hoses, place pressure sensor back, build in starting motor, fill with oil, contact on, and press the starter button.....

 

[ballbearian]

Incredible. Are you injecting a fixed amount of oil or filling it till it comes out the breather? Would rotating the crank while doing this aid the process? The components which are normally splash fed would require a greater volume to be submerged, I would think. I can't imagine you'll have much to clean, as tidy as you are. Incredible, just incredible.
I've never heard of a bike on dialysis.

 

[jensen]

Thanks, no the oil is flowing back via the oil plug hole into the plastic container. The oil is sucked out of the container, via an oil cooler into the filter system, creating an endless loop. The oil cooler is used by me to heat up the oil, up to 100 degrees celcius, this way the whole engine is hot during the process. I always do this with a new build engine, the setup is always ready and at hand, so not much effort when having it. The oil is under high pressure, so all bearings are lubricated and cleaned this way. This loop will run for 1 or 2 days or so.

The engine cases, cylinder head and all other painted parts are blasted (wetblasted or with grid / glass), and although I cleaned them all meticulously, this method will flush out everything (if any) in the oil lines and channels in the engine. That's the only reason I do it this way. That's why I also remove the oil pan after flushing to see if everything is perfectly clean. If not, I'll flush again, until I find nothing any more. Residue in the cases itself will be filtered out by the oil filter when the bike runs.

 

[jensen]

Yesterday I did remove the sump from the engine after 48 hours of flushing with oil and no debris of any kind was found. Time for the next steps working toward a first start-up of the engine.


After removing the 2-stroke-oil/petrol mix from the fuel tank, I filled the tank with ethanol free gas, and for the next 24 hours I will check if the fuel **** is in perfect working order. After that I will fill the carbs with petrol and see if everything is gas-thigh. Ignition is adjusted (static), fuel lines are ready to connect, muffler is mounted. If nothing strange happens, the engine will run next weekend.

 

[stl360+450]

If nothing strange happens, the engine will run next weekend.

I'm penciling it into my calendar.

 

[jensen]

Fuel....................check
Compression.........check
Spark..................check

So everything ready the first run. Last Friday was a great day to hit the starter button, and after a few coughs, the engine started.

https://flic.kr/p/2o3UqD4

After a short run (first heat cycle), no signs of leakages, overheating, strange sounds, smoke, vapours etc, so everything seemed to be in order.
Meanwhile I added the muffler and I did a few other short runs, went through the gears, checked the electrics etc, no issue's found so far.

Now waiting for my rear mudguard (still at the plater for re-chroming) and nice weather in March before I can actually hit the road.

But for now, the bike is finished and after countless hours I consider the job as done.

FINALLY.

 

[stl360+450]

Congratulations and thank you for sharing the journey with all of us and the many non-members who likely scroll through. It didn't sound bad at all without the muffler, so I imagine it really purrs with it on. I'm hoping to see a few advertisement quality photos once you're able to take this bike out to some of the scenic spots in your locale! On to the twins!

 

[ancientdad]

It sounds good, and it's always nice when everything goes as planned.

 

[LongDistanceRider]

Sounds good Jensen, very nicely done there.

 

[jensen]

Thanks for your comments.

It was a long journey of 13 years, which begun with the fact that I couldn't adjust the cam chain any more.
Meanwhile we raised two sons (now 18 and 22 years old), changed jobs twice and build a few Honda twins.