Topic: 1975 Honda CB400f Project - Beginner

[gjunkie]

I'm late to the party on this, but I have just finished reading this entire thread.   As a guy who is capable of doing brakes, plugs and oil filters...I'm very impressed.  Great work and hope you enjoy the fruits of your labor.

Thanks for the kind words Lyle! I see this as the beginning, not the end, of a great journey and build.

[gjunkie]

So I've been riding it now for a few days paying attention to all the sounds, the feel, etc. In the past three days I've started noticing three different squeaks, one from the front breaks, one from the rear drum, and one from the wheels while coasting. I took a quick look at the front pads and here's what they look like... they don't look quite straight.



Also took a close look at the tach/speedo. They're a bit loose and in not-so-good condition.

[gjunkie]

I've noticed that it leaks from the gas cap if the tank is full when accelerating or going uphill. Could this simply be due to a bad gas cap gasket?

[gjunkie]

It's been a while since I've posted so I thought I would give an update for anyone interested.

The motor is running like a charm. No issues.

I decided to paint the lower half of the forks matte black, but in order to do so I have to take them completely apart. So I thought why not rebuild them since it probably hasn't been done in 30+ years.

So I got to work. I watched several videos and read many posts about the difficulty in removing the bottom bolt as it can spin freely if you first remove the spring. I left the spring in there and didn't have too much trouble. The oil was a very dark gray/black. No idea if that gives an indication of how long that's been in there... I'm guessing very long.

I was able to take apart the shock completely except for the all-elusive fork seal. That thing is IN there. I tried heating up the top to try to expand it a little, but no luck. I saw someone compress the shock with a car lift and force the seal to pop out... I don't have a car lift... Does anyone have a trick on how to remove that seal?

[Rocketman]

My favorite way to remove fork seals is to use a motorcycle tire iron and pry them out.  Be sure to use a scrap piece of aluminum to protect the tire iron from marring the top of the lower fork tube.  Tire irons are much wider than a screw driver which I do not recommend using, too easy to slip and damage the fork tube.  Be sure to wear eye protection and proceed with care!

[Bankerdanny]

Yep, large sturdy flat bladed screwdriver, a shop rag to protect the top of the leg and elbow grease. It will come out.

I know my GL1000 forks have a metal spacer under the seal and you need to be carefull to get the blade of the screwdriver between the seal and the spacer.

[gjunkie]

My favorite way to remove fork seals is to use a motorcycle tire iron and pry them out.

As soon as I read this I went out and got myself a set. This was perfect! Got the seals out in seconds. Thanks for the recommendation Rocketman!

I put on 1 coat of primer and 2 coats of matte black on them. Here's a photo of each stage.



I'll check on these bad boys after 24hrs to make sure they fully dry before I start handling them. I've also gone ahead and gotten a new, black brake lever/master cylinder assembly. So since I have that off along with the brake caliper, I'll be disassembling the caliper and repainting it. It was black, but the paint is all chipped. It could use a good cleaning and repaint to match the bottom of the forks. The brake is a little squeaky so I'll probably look into that as well.

Overall, I'm very happy with the initial results of this paint. I should be fully rebuilding these this week, can't wait to see what they look like back on the bike!

[Rocketman]

Glad the tip worked.  Good to see a 400 four project.  Enjoy the ride.  Unlike LA it is shop time in cold and snowy Ohio!   

[gjunkie]

Finished reassembling the forks and since the brake caliper had a bunch of its paint chipped away and it squeaked I decided to disassemble it, paint it to match the fork, and rebuild it.



From what I can tell the bar on this bike was not original. The controls were, but not the bar. I've been wanting to replace it with a set of clip-ons so I got a set of black ones, but of course the wiring was run inside the bar. It took quite a bit of effort to pull out the wiring. After further consideration and inspection I decided to replace the original controls since the kill switch control was already a bit damaged and in all truth I just didn't like them. At this point I said what the hell and replaced the triple tree as well as I don't need the old one for the old bar.

For a while I was hoping to retain as much of the original front end, as far as speedo/tach & headlight, as possible, but ultimately decided replace the speedo and tach duo for a single speedo. Basically, once I committed to not keeping original controls and other pieces I went with it.





I know I'm probably ruffling some feathers here for the purists, but what I truly want to do is get it running perfectly and customize it, not necessarily restore it to factory settings.

Now, the moment I decided to replace the headlight, speedo, and tach I knew that there would be a decent bit of electrical work to be done here. The original blinkers will be going as well, which are grounded inside the headlight, the wiring from the speedo unit to the harness isn't the prettiest, a few wires have extensions attached that don't match the wire colors coming from the harness, and all wires have soldered connectors which don't match my new ones, etc.

So I ordered a new speedo and controls from Dime City, they arrived and I started looking at the electrical to see how to hook up the new one.





After some thought I was thinking about getting a plastic wire connector rather than hooking up each wire individually (as they are now) with solder-less connectors. However I'm not too sure if this is the right approach or not, and if it is which connector to go with (gauge, etc). I have no experience in this department, but I feel comfortable and up to the task.

Eventually I want to make my own harness, preferably when I start working on the seat/rear end, to fit my needs. So I'd love to have the front end of the electrical easy to unhook when the time comes. Plastic connectors seem like the way to go.

In summary: What do I need to look for if the plastic connectors are the way to go?

[NobleHops]

Hitachi style connectors are as close to 'correct' as you'll find, although they are a little bulky. I have had good luck sourcing components at http://vintageconnections.com/, but beware you need to buy a connector with enough slots for your wires, plus the male and female spades that insert into the connectors, and you'd be wise to get the proper crimper and removal tool too. After you get it all crimped but before you insert them into your connector you should tin the wires. The tools and supplies will make this one connector an expensive start, but IMO you definitely want to be able to disconnect this stuff.

[gjunkie]

Hitachi style connectors are as close to 'correct' as you'll find, although they are a little bulky. I have had good luck sourcing components at http://vintageconnections.com/, but beware you need to buy a connector with enough slots for your wires, plus the male and female spades that insert into the connectors, and you'd be wise to get the proper crimper and removal tool too. After you get it all crimped but before you insert them into your connector you should tin the wires. The tools and supplies will make this one connector an expensive start, but IMO you definitely want to be able to disconnect this stuff.

Thanks for the tip! This is precisely what I was looking for. I've already got a crimping tool, but don't yet have the removal tool, which I'll definitely need. Thanks again!

[NobleHops]

Happy to help!

[NobleHops]

I've noticed that it leaks from the gas cap if the tank is full when accelerating or going uphill. Could this simply be due to a bad gas cap gasket?

That would definitely be my first guess. Take a beady-eyed look at it up close and see if its obvious.

[gjunkie]

I thought I'd give anyone who's interested an update on the bike. After the case was cracked and had the motor rebuilt, I don't think it has ever run better. My best friend and I just rode our bikes, he on his Yamaha XS750, from LA to Portland, OR, where I now reside... about 1200 miles. And after all that, not a single drop of oil leaks from the motor. I couldn't be happier.

When we decided to move I knew I wouldn't be able to take the bike with me, so I left it behind at my friend's place where he could get some work in... specifically things that I couldn't do myself, like fabricate/weld a new seat. Since that was happening, and the backend was to get ripped out, these were the things we decided on:

- Remove rear fender/brake light/blinkers
- Remove old seat
- Remove old battery and everything under the seat
- Rip out old wiring harness

First things first, remove the seat and all unneeded tabs, etc, and weld a new seat/pan:





I really dig the tail slanted up look, and wanted to have the upholstering angle up in the front to match the angel of the tank as close as possible. The seat is awesome. However, the upholstering came out fairly terrible. They warped it in the front a little, so it angles up slightly. And it looks like bug... Planning on having that re-upholstered here in Portland by someone who knows what they're doing.



After ripping out the old harness we decided to go with an M-Unit. So a battery box was fabricated to mount below the seat. The pan holds the new 4-cell Antigravity battery, the M-Unit and the key switch:





For anyone curious, the 4-cell was perfect for this bike. Haven't had any issues.

Wiring was an adventure. The switches I had purchased from DCC were absolute sh*t. All of them had colors mislabeled, and used completely different colors than what was marked on the box, which led to many confusing moments. Never again will I buy electronic components from them. The M-Unit is a joy to work with. It simplified everything. Run each individual circuit and you're set. It makes it very easy to test and make sure each system is working properly. In addition, you can program the M-Unit in what seems like an infinite number of ways... running light brightness percentage, blinker linger length, etc.





So we decided to forgo the left controls for headlight and blinkers, which were causing all kinds of wiring headaches, and mount them on the headlight unit. I'm not sold on the blinker switch up there, but there was no other way to mount them since we were going for a small on-off-on toggle switch.









A new plate bracket was also made:





A problem we realized a bit too late was the rear tire clearance with brake light bracket and blinker wires. This is with my buddy sitting on it and pushing down with some force:



Almost any bump on the road and I bottom out, so I'll have to figure that out.

Towards the end of my time in LA we simply had to get the bike working and get on the road. We had a limited number of days until we both had to get back to work. So some things definitely feel hacked together. Regardless, I'm super happy with how this is turning out.

As far as performance, the only thing I noticed is that once I reach speeds of about 60-70mph it is difficult to continue climbing. I topped out at about 80mph, but I would imagine it can do better than that considering these bikes were built with racing in mind...

We hit a few snags on the road, but I only ran out of gas once! ha. We took the scenic route, starting from LA up the 101. Stopped in Santa Barbara for the night. The next morning we rode through the Santa Ynez Valley, wine country, and continued on the 101 all the way up to Monterey, slept there.



From there we crossed SF and the Golden Gate bridge and spent the night in Napa. Then continued on up to Eureka.



The next day rode through the red wood forests, which was breathtaking.





Stopped in Coos Bay, then the next day, the last one, hit some pretty bad rain on the home stretch... we powered through it, but I'll never do that again....



Would love to hear your thoughts! Ride on fellas...

[Tews19]

Pretty awesome feeling riding after a rebuild huh! The brake light looks like you can more it higher towards the front of the hoop? Possibly help others noticed it more rather then being tucked deep under the seat?

[calj737]

I'd spring for the purchase of a 1 inch smaller rim and new spokes for the rear. That, plus a tire aspect ration change should create enough clearance for your brake lights.

+1 on the M-Unit.

[gjunkie]

@Tews19: Yeah possibly. Not sure I'd want it all the way at the end of the hoop, but if not, it would be at an angle, so I'd have to account for that. But yeah, it was a blast. I will say, I'll never do long distance on this bike again tho... My back was destroyed. It would definitely help if I got some rear sets, as now I'm leaning forward more than before, so Im like in a fetal position on this thing.. I need my legs to be a little further back.

@calj737: That's a good point about the wheels. I was planning on getting newer tires. I was definitely slipping and sliding a bit on the ride, which was a bit freaky. Something with a little more tread would be great. Going 1" smaller might just be the difference maker.

[gjunkie]

I've been trying to find some info on how to install a tach plug, hoping someone can give me a hint. I bought a plug from 4into1.com (http://4into1.com/ttr400-aluminum-tachometer-blanking-plug-silver-honda-cb400f/), and in the documentation it says "Covers must be removed for fitment."

Does that mean the top of the head has to come off? When removing the tach cable, this is what it looks like:



From what the 4into1 guys told me, the threaded end has to face outward in order to be able to pull it out. If that's the case, this bit you can see in the photo inside the hole needs to come out. Thanks in advance for any advice you can give!

[calj737]

What you see in there is the gear. Extract it, then the plug will fit. That gear meshes to a corresponding gear on the camshaft.

[gjunkie]

What you see in there is the gear. Extract it, then the plug will fit. That gear meshes to a corresponding gear on the camshaft.

Gotcha. So I'd have to take the head cover off to extract it, then torque it back on? Thanks for the help calj737.

[calj737]

You should be able to wriggle it out without removing the head cover.

[gjunkie]

You should be able to wriggle it out without removing the head cover.

I tried to wiggle it out of there today but no luck. It is REALLY in there... Is there a trick to this?

[calj737]

If you have the retaining screw out of the cover, then try rotating the crank as pull on the tach gear. If that doesn't work, cover is coming off 

[thirsty 1]

I hate tell you this but you need to remove your rocker cover to get the tach drive out.  It has a C clip holding it in place. Back out your valve adjusting screws and remove the cover. 4 screws under the breather housing.

[calj737]

Must be a 400 thing- thanks for clarifying that for me, Thirsty.