Yet Another 400F build

bikeboy

New Member
Yes, Yet Another CB400 four build for y'all. I thought I should start a build-thread on my next project now that I'm done with the Super Bol D-Or.

I got this little "gem" from a friend of a friend, who had it sitting outside around at his farm unloved and unused for years. I'm reluctant to call it a barn-find, because a) we don't have barns over here, and b) it was outside in the elements anyway ;)

Apart from spending all my money and time on the 900, I didn't want to invest too much in this project until we had the paperwork sorted. In order to prove transfer of ownership of an unregistered vehicle I had to organise a Statutory Declaration from the previous owner saying he has given the bike to me. (Yep. Got it for nothing. Well in these days of the beer-economy, a slab of Carlton Draught-which is worth next-to nothing ;) ) Problem was that in the meantime, this guy had moved a couple of hundred Kms away, and I had to deal with a third party to track him down, get him to sign in front of a JP/Police Officer witness, and send the papers back. Took just under a year, but we're good to go now.

Here she is the day I got her home:



A little rough, but some useable bits there. Somewhere.

Interesting flora and fauna under the seat:



Under the tank was slightly cleaner:



Forks and brake – not so good:



This was the caliper I swapped with Justinas for one of those cool Russian haedlights for this project. I did manage to clean it up a bit first:



So the first step was strip her to bits.



I made a stand for the motor, and set to work massaging some movement back into that.



I have no idea why this bike was parked up, but I thought some mechanical catastrophe was to blame. I pulled the plugs, and poured some oil down the holes and let it sit for a couple of days. I gently tried the kick starter, and all the little bits and pieces seemed to be moving in the right direction, so after a few more rotations, I hooked a battery up and tried the electric start. Again, all good, so I hooked the compression tester up, and got good readings across the board, so that made me happy. A few months later, and the readings are still strong. The speedo has 15000 Kms on it, and I'm thinking that could be accurate. I pulled the clutch apart, and there's very little wear. All the valves were within spec. The rear brake shoe is almost new, and the disc pads look great too. Footpeg rubbers show very little wear. I'm starting to think he just got sick of riding it? I haven't tried to start it yet, because I drained the oil and can't find the spring that goes in the filter-housing :( I've also rebuilt the carbs, and they're ready to go back on.

The Plan
Well, I should state from the outset that this might not be a 'classic' cafe racer. It won't be a bobber or fighter, so I think this will be the best fit. To be honest, I'm not sure how it will end up, but I will be doing some suspension mods just to bring her up to date a little bit. Having felt the difference it made to my 900, I'm not sure I could settle with a 'restoration'. To this end, I started playing with a few bits I had lying around (still unsure if I'd get the paperwork), and fitted a pair of cbr600 F2 forks to the 400 stem. The originals were shot anyway. 2 new bearings for the wheel, a couple of spacers, bingo bango - new front end. The next challenge was to mount a pair of disks for the twin calipers. After initially trying some 900 units, I settled on a pair of cbr900 floating disks. Much cooler. I also pulled the front wheel apart to see if I could re-spoke these things myself. Turns out I can :D



I needed a couple of spacers/adapters turned up, but my brother came to the party, and made 2 16mm aluminium plates with a centre boss that fit perfectly. I drilled and taped 4 holes for the new disks, and was able to use the 5th and 6th holes + another 2 to mount the whole lot to the hub using the original 4 holes. Sound complicated, but I only ended up drilling 2 new holes.

So here she is sitting patiently on the lift, waiting for some more TLC:



The Marzocchi's are there just to support the rear end, but I'll be looking at piggy back shocks of some description.

So there you go. You're all now as up to date as me, and we'll wait to see what happens next ;)

cheers
ian
 

bikeboy

New Member
Re: YA400F build

revheadgl said:
PS, Bet youre glad I didnt take you up on the offer on the forks lol.

I like your engine stand to, might have to make on myself now that I have a welder.
No sweat Glenn. That was a set of F1 forks. They're still down the back shed somewhere. Now, do you need a pair of VF1000R 'spike' comstars ;) VF750 gold boomerangs perhaps? I wish I could develope a plan and stick with it!

I'm really hoping this motor is as good as it appears to be. Should be able to get her going in a week or two.

cheers mate
ian
 

Big R

Heaven is so far away.
Re: YA400F build

That's it, I'm signing up. Gotta see where this one goes too......

Ian, i believe your last pic is out of sequence.
 

bikeboy

New Member
Re: YA400F build

Big Rich said:
That's it, I'm signing up. Gotta see where this one goes too......

Ian, i believe your last pic is out of sequence.
cool. hope I don't disappoint ;)

I do believe you're right about the pics. fixed it now. Good catch.

cheers
ian
 

bikeboy

New Member
Re: YA400F build

revheadgl said:
I have a few ideas already for the next build...What am I talking about..I havent even really gotten started with the current build LOL!

I am sure you wont disappoint us. Any plans on tank/seat colours etc?
ahh. so it's not just me that does that eh? Always thinking ahead of myself. Having said that tho', no, I haven't got to the cosmetics yet. I'll need a new seat, because the old pan was rusted in half. Not sure which way to go with that yet.

cheers
ian
 

Kanticoy

Mad Science!
DTT BOTM WINNER
Re: YA400F build

Yep, I'm in too! Love the wheel, I'm planning something very similar.

Sent from my ADR6300 using Tapatalk
 

sxecafe

You think the Carpet Pissers did this?
Re: YA400F build

Let's get this show on the road. Should be a good one.
 

bikeboy

New Member
Re: YA400F build


Well guys, I finally got around to trying to start this little beast. I put together a rough harness to give me ignition, oil pressure and charging.


So here we go. This isn't the first start, but it's not long after. Probably took no more than 2 minutes to get her to fire and run.


firstStart.wmv


I put the old headers on to handle the exhaust, and this is what blew out of them (no. not the tools-the rust ::) ):





After some time it became apparent there was an issue with #3 pot. The exhaust wasn't getting as hot as the others, and it seemed to be missing. I checked the spark again, and swapped plugs, and saw #3 was a bit oily. Fired her up again, and sure enough, blue smoke coming from #3 pipe. Bugger. I think I found the reason this bike was parked up all those years ago.


Time to pull some covers. Fortunately it seems you can do a top end strip of these with the motor in the frame! win!





Anyway, barrels are now off. Bore looks OK in all. Pistons and rings seem OK too. None broken, and all there.





I'm thinking it might be valves/guides/seals. Then I noticed there are no valve stem seals at all on the exhaust valves? Is that right? They seem to have a different end, and the gasket set I bought awhile ago only has 4 (inlet) seals.


What I did notice was that each piston has a mark that appears to have been impact from the exhaust valve? It's a shiny area on each crown, not deep, just enough to prevent carbon build-up by the looks of it:





I didn't hear any knocking while it was running, but maybe the timing chain was a bit loose, and allowed some overlap? No damage on any of the valves. They're not tight in the guides, so I don't think they're bent? I'll lap them in again and they should be good to go.


Either way, I'm thinking I'll pick up a big-bore kit for it.


So all-in-all, an interesting time was had. At least I know what needs to be done now.


cheers
ian
 

bikeboy

New Member
Re: YA400F build - it's alive! briefly :(

revheadgl said:
Piston is quite wet, looks more like worn/damaged ring/s.
Glenn
Yeah, that's what it turned out to be Glenn. The ring end-gaps were way out, and while the bores themselves weren't to bad (#3 had a bit of light scoring), I've picked up a 466cc kit, so the barrels are away being bored.

I've painted the head and put it back together:



The observant among you may notice #1 piston isn't in the corresponding tray, because it's sitting on my desk at work as a paperweight ;)

I've also gone for the ever-popular unpainted edge-fins. I won't be polishing them, because I'm not a polished kinda guy. Brushed satin is more me:



I've already factored in a new cam chain and guides, so that was no surprise. Next I have to pull the rest of the motor out of the frame and get stuck in to that. I wasn't planning on it, but I guess the worse thing I can find is the bearings are shot too.

cheers
ian
 

bikeboy

New Member
Re: YA400F build - it's in pieces :)

Well. It's been a while eh ::)

Pulled the cases apart. That was interesting. That weird little horse-shoe type tensioner arm seems to have complicated the assembly somewhat. It seems that at some point the pivot has become fouled, and the arm wouldn't provide any more pressure to the tensioner. There are marks on the head that seem to indicate the chain was flopping around for a bit. Have replaced the arm now.

The bearings look good. In fact the big-ends have non-honda nuts on them, leading me to believe they may have been changed at some point.

The Barrels are (still!) away being bored. My machinist has let me down a bit here. I've had a delivery from David Sliver's in the UK, and also a seal kit from the states all in the time I've been waiting for my barrels!



I've done just about all I can do now until I get them back. I've painted all the cases/covers:



I also tried a test-fit to see if I could get it all back together. It's not as straight-forward as the 900! You have to install the primary chain to the shaft, and sit the lot on the trans while you drop the bottom case on and insert the primary shaft through the oil pump opening in the side, using the oil pan opening to align the starter clutch, gear and spacer. I needed the practice.





...and then I got bored. Unlike my barrels!

Thinking that SURELY my barrels would be back before anymore ebay orders arrived, I counted up all the 6mm case cover bolts I need and in what sizes. I took the list to my bolt guys, and got a set of stainless socketheads. They came with a plain knurled edge that I could take or leave. Or actually just leave. So in an act of mind-numbing tediousness, I proceeded to put each one in turn in my drill press, and file the knurled texture off. Not only that, but then take some fine emery cloth and dress the surface up for a nice brushed finish. Highly polished surface don't do anything for me, and I'd rather look at a nice satin brushed finished. Apparently I'm quite anal about it.

Here's the process:



And don't stop until you've done them all:



I've since installed the new seals, and honda-bonded the cases back together.

I've also welded a mount for the 350f tank I think I'll use. Silly me thought that if I found the centre line of the frame, the tank would sit in the right spot. Turns out it needs about a 10mm offset to sit evenly at the back.



And now I wait again.
 

crazypj

Split personality, I fake being smart
Re: YA400F build - some of it's going back together

How long are the tensioner and guide blades?
I know 400F uses same method for chain adjustment as 360.
400 may be shorter though?
BTW, I'm not OCD, just like things right (saw post on SOHC4 yesterday ;D )
 

bikeboy

New Member
Re: YA400F build - some of it's going back together

crazypj said:
How long are the tensioner and guide blades?
The tensioner is 225 mm, and the guide is 190mm:





Any help Crazy?


I know what you mean Glenn, but at the moment I'm about to divert the funds to a little performance something for the 900, so barrel-boy might have to wait to get paid anyway ;)


You're a better welder than me too Glenn. If I tried to extend those tabs I'd burn them to smithereens. I'm comfortable tacking the odd captive nut, but that's about it ::)


cheers guys
ian
 

bikeboy

New Member
Re: YA400F build - some of it's going back together

revheadgl said:
Ha, you must be a really bad welder if I am better than you!
yeah. I'm shit at it ;D


Fortunately I know a boiler-maker that can stick-weld baked bean cans together, and I use him for 'the good stuff'

What type of seat are you going to use? I still havent decided which way to go yet. I made one but wasnt happy with it, so I started again but am still not happy. Dont worry, I wont copy you!

Glenn

I was hoping to copy you :-\


Hurry up fella.
 

bikeboy

New Member
Re: YA400F build - some of it's going back together

revheadgl said:
Very good! ha.

Something like this one?

I can see potential in that. yep.

not sure about the material covering it but.
 

bikeboy

New Member
Re: YA400F build - some of it's going back together

One of my HT leads was all manky as it exits the coil. The insulation was torn, and the wire was exposed. It would short when I turned the ignition on, but would run OK. It was a definite weak-spot just waiting to fail.

Some time ago I grabbed a length of vintage cloth-covered lead I found from a link here somewhere, but did no more than that because the coils and leads seemed to be a sealed unit, and conventional wisdom said they couldn't be repaired.

Well. I had a bit of time, so I gave it a go.

First step was to expose the lead, so I dremeled a channel down to give me some space to work in. You can tell when you hit the HT lead, because the rubber starts to smoke and smell :)



*CAREFULLY run along the top edge of the wire, the using the dremel gain, cut through the outside edge of the wire. Now you should be able to twist and pull out the old HT lead, leaving the bare wire exposed.

*I'm thinking now that you might not have to do this? If you can cut through the conductor, you still should be able to pull the lead out and expose the wire? Not sure. Didn't try it this way, but would be less chance of damaging the old wire if it worked.



This is the section I used to make the connection.

Strip and appropriate length of a new lead, and feed it through the hole until it overlaps with the old wire. Check if you have enough for a good join.

I then marked the lead with some tape, backed it out a bit, and ran a bead of hot glue around it about 10mm 'in'. Feed it back in to butt against the old wire again, and you should have a nice (hopefully) watertight seal around the entry point.

Solder the two wires together:



Pack the join with as much hot glue as you can get in there. The aim is to make it watertight, and support the join. The glue will stay reasonably pliable, so shouldn't shake out.



More packing. My first attempt at keyhole surgery :D You can see the 'oozy' bits of glue around the leads at the coil. I'll leave them there for a bit more protection



cheers
ian
 

bikeboy

New Member
Re: YA400F build - some of it's going back together

Finally got my barrels back from machining, and have fitted the new pistons. Boy. That was a fiddle. Working on 4 small pistons takes some patience. I'm thinking a a 450 twin would be easier to work on. Maybe next time.





Things are moving along again ;)


ian
 

crazypj

Split personality, I fake being smart
Re: YA400F build - some of it's going back together

Still haven't measured CB360 tensioner and guide
Motor is looking good
Just one question why YA400F?
Yamaha make YA, it's a scootor
 
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