Topic: 1975 CB400F -> Project "something fun to build and ride"

[Syscrush]

I'm going to toss out 2 suggestions that are mostly aesthetic, and they're the same suggestions I made to FJ who set up his bike with this same front end.

1. Remove the caliper mounts from the fork lower that you run without a caliper.  It looks sooooooo much cleaner.

2. Blacken the bright blue anodized bits on the caliper - they are a modern Yamaha signature item and they look out of place on a vintage Honda.

Free advice and worth every penny.

[gsnorcal]

Today's accomplishment was splitting the cases.



Next up, clean the cases, then start measuring tolerances with Plastigauge.

Exciting stuff!

Dave

[gsnorcal]

Syscrush,

I agree with #1 completely. However,  #2 is not cut-and-dry. There is nothing "period incorrect" about having "trick mods" on these bikes, and some of them were anodized. For instance, my *original* Lockhart oil cooler has red and blue anodized fittings. Bling existed in 1975.

But, yea, I understand your point (and read it over in FJ's thread, too  )

Glad to have you following along!

Dave

[gsnorcal]

See the two grooves highlighted by the red arrows? They appear to be worn by the cam chain. Anyone ever seen this? I'm thinking I should at least file down those jagged bits.

Dave

[Kanticoy]

Yep, I had the same problem in several of my motors too.  If that is the case, then your slippers were either worn or broken just like mine were which would explain the trash in your oil passages.  That same problem fried my CB360.  I would file the edges smooth just like you stated that you were gonna just to relieve the harsh edges and prevent possible stress fractures.  Undoubtedly the horseshoe tensioner got seized on your motor as is extremely common on the 400f from what I've read.  Maybe some people can chime in and offer some suggestions on how to fix that issue.  I noticed that Kevin from TTR400 (South Africa) offers a billet replacement that he guarantees not to fail.  I'm tuned in man.  You've got some great stuff going on!

[Syscrush]

However,  #2 is not cut-and-dry. There is nothing "period incorrect" about having "trick mods" on these bikes, and some of them were anodized. For instance, my *original* Lockhart oil cooler has red and blue anodized fittings. Bling existed in 1975.

I'm not going to harp on this, but do want to explain my point - it's not that it's too shiny or blingy, it's that it's a part that screams "YAMAHA".  Those forks are great, and you're doing great work with them.  But the blue circles on the calipers are such a distinctive, signature piece that I think it looks out of place.  It's almost like putting GSX-R graphics on the bike IMO.

Of course, it's a personal thing and it's your bike.  And it's funny, if you were throwing on headlights and a flyscreen from a Buell, I wouldn't think anything of it.  Same goes for a Ducati SSSA, or mirrors from a SportClassic.  So this is probably just my own personal hang-up. 

Glad to have you following along!

Thanks - I'll stop being a pain now. 

[-CB-Jamie-]

Subscribed to this thread. I'm pretty interested in what you do here as I might try something similar on a future build with the r6 front end. Good luck with it.

Don't know if you ever came accross the ''cb400 four bits'' website but you'd probably get that rubber gasket that broke on the carb from him if you want to replace it. He just parts cb400f's and has pretty much anything you might need.

Here you go
http://www.400fourbits.co.uk/

[stay youth]

Im running one of ttr400 cam chain adjusters, its much beefier

[gsnorcal]

Mailman was good to me today:



The big-bore kit from eBay dude in Japan looks great. Well packaged, faster than anticipated delivery. And the parts look quite similar the OEM pistons (oil holes, etc). I ordered a second set of rings and a second head gasket, too.



This used rim was also from eBay. It's the same size as the stock front rim, 1.60x18, but in 40 spoke to match the 550 hub. Lacing pattern is identical to the 550 rim. So, I ordered spokes from Buchanan today as well. Pricey at $200 for front and rear, stainless with stainless nipples. Nipples are .281", so I'll have to drill the rear rim out a little. I just wanted them to be the same size front and rear.



Finally, I received the aluminum stock that I need to finish the front hub project. The 4" round is 6061 for the carriers and the 1.25" is 7075 for spacers.

Dave

[gsnorcal]

I also measured the crankshaft with Plastigauge today. On the 5 bearings I got 4, 4, 3, 3, 3 (1/1000"). As I understand it, the service limit is 0.0032". So, two of mine are clearly out, and the other 3 are darn close.



Problem is that I don't have this measuring tool to check the ID of the cases. Is there a shortcut?

I measured the crank OD and it was 1.260-1.261" (32.004-32.029mm). That puts me in the first column of the table. Actually, it's *bigger* than any they spec. So it doesn't appear to have worn at all.



And the cases don't wear. So, can I safely just replace the bearings with the same "color" code that is currently in there? Or is that totally insane?

My bearings are all marked D5C-A STD, except the one nearest the points, which is D5B-A STD. I interpret that as C and B, or green and brown. Correct?

Guess I'd better check the rods as well.

Thanks,
Dave

[RickB]

Dave,

I had the exact same problems your motor has. The worn cam chain housing and the stripped tensioner bolt.

What had happened with my motor was the head gasket was installed upside down by the previous owner. This gave the impression that the cam chain was tight, as it pressed again the gasket. As soon as the engine was started, the cam chain shredded the gasket into the engine, the cam chain flopped about and just caused a mess in there.

So I replaced all the cam chain components I could. New tensioner blades and bushings, the TTR billet tensioner, a heavy duty race cam chain (both from Kevin at 400FourStore.com)... I even chased down a NOS camshaft  (found that at an Australian store bkperformance.com.au), performance springs and new valves while I was at it. I had the threaded tensioner bolt repaired by an aluminum welder. The cam chain tensioner is a weak area with the 400F engines by all accounts, I didn't want to take any chances.

Rick.

[FunJimmy]

Finally, I received the aluminum stock that I need to finish the front hub project. The 4" round is 6061 for the carriers and the 1.25" is 7075 for spacers.

Dave

Hey Dave

Keep those pictures coming.
Those pistons look really nice.
You couldn't use aluminum tubing for the spacer eh?

Cheers
Fj

[gsnorcal]

You couldn't use aluminum tubing for the spacer eh?

Doh!

 

[gsnorcal]

Con rod side clearance limit is .0059". I can get a .007 and .008" feeler in.

What's the remedy there?

[FunJimmy]

Con rod side clearance limit is .0059". I can get a .007 and .008" feeler in.

What's the remedy there?

Ear plugs! 

[Syscrush]

You couldn't use aluminum tubing for the spacer eh?

Doh!

 

That's gotta be one of the funniest posts I've seen on this board.

Anyhow, this way you can get it to exactly the right ID and OD. 

[gsnorcal]

Today I pulled the con rods from the crankshaft to measure bearing wear. Three of them are still within spec, but one is right on the edge, so I'll replace at least that one. I want the bottom end to be bulletproof since I am in there.

Checked the primary shaft drive rubbers. There is slop in there, as well as the rubbers being quite brittle. Another item for the replacement list. The primary chain is definitely getting replaced as well. It had started to wear on the guides, plus its got tons of side deflection.

A pretty exciting moment was getting the R6 triple clamp mounted up. The old races came out easily, and the new All Balls tapered bearing races pressed in just as easily. It's a lousy picture, but you can see the bottom seal was placed on the stem, followed by the bearing. Then it slipped right in. The upper bearing has the seal above it and then the two R6 nuts. The top clamp fits on nicely and the nut has plenty of thread to grab, and still doesn't bottom out. So, in a word, PERFECT!

The stock steering stop is too wide for these triples. I can only move the bars through 10 or 20 degrees. That will be easy to trim once I get the tank on.



Until tomorrow,
Dave

[FunJimmy]

The stock steering stop is too wide for these triples. I can only move the bars through 10 or 20 degrees. That will be easy to trim one I get the tank on.

Dave

That's interesting. On the CB550 the stock steering stop doesn't even touch the triple stops.
Nice work. Hows the hub spacers coming anong?

FJ

[gsnorcal]

Nice work. Hows the hub spacers coming along?

Shop classes are only two days a week, so I won't get more done until Tuesday.

[gsnorcal]

Started turning down the brake carriers:



And got this far. It's bored all the way through, with a bearing pocket on one side. I actually screwed this up a bit. The bearing doesn't have an interference fit like it should. So tomorrow I will shift everything down one bearing thickness. Luckily I have extra material. But the fit between the little collar and the hub/rotor is perfecto!



I also removed all the old gasket material from the engine cases over the last few days. They've all been through the parts washer numerous times now. They are ready for a final paint stripping before soda blasting, final cleaning, primer and paint. At the moment I think I'm gonna use VHT Nu-Cast Aluminum and/or Nu-Cast Iron.

Gasket set and oil seal set are in the post. I'll inventory them and then order up all the remaining parts for reassembly.

Oh, and this Mac 4-1 is on the way to me as well. I chose this one because it has the shortest muffler of all the ones available for the 400. I ordered it early so that I can have it on hand for mocking up any frame modifications.



As soon as my valve spring compressor arrives, I'll be taking the valves out for inspection. Then the cylinder goes up to the machine shop for boring to 466 cc. I have high hopes that the head needs only lapping and new seals. Perhaps new guides.

That's all for tonight.
Dave

[gsnorcal]

I dropped off the cylinder to be bored out today.

Valve spring compressor arrived and I measured everything in the top end. It's all within spec. And I showed it all to the guys at the motor shop and they thought it looked ok, too. Hooray! So, all I need up there is new valve guide seals and to lap the valves, which I did this afternoon.



Off to the machine shop now to get back to work on the hubs.

Dave

[gsnorcal]

I finished turning the disc/hub carriers last night. I also got started on the drilling/tapping operations. I'll finish these today. I haven't decided on a finish yet.







I ordered the fasteners from McMaster-Carr last night.

Dave

[gsnorcal]

I picked up the cylinders today. They look beautiful. 466 cc big bore! I recommend Engine Dynamics of Petaluma, CA. Great folks, and very knowledgeable. 30+ years in business, doing specifically this type of motor work. They were kind of jazzed about this project. Pardon the heavy coat of oil obscuring the nice crosshatch.



Boy, there isn't much material left on the bottom of the cylinders. Thin walled and hardly any bevel at the base, though Mike at ED took the extra time to put as much bevel back as he could.



Mike also gave me an assembly tip: insert the #1 and #4 pistons into the cylinder first. Install the #2 and #3 onto the rods. Lower the cylinder down onto #2 and #3. Once they are in the cylinder, tap #1 down to its rod and secure it. Repeat with #4. That way you only fight 2 sets of rings, and only have to deal with the two outer wrist pin clips while in place. Seems worth trying to me.

BTW, Mike also told me that the pistons (from eBay member cruzinimage_co) are nice pieces. He says he has installed a few sets of them before and they are good kit. That's nice to hear.

At the machine shop tonight, I just about finished the hubs. I need to tap 4 more holes and that's it. I think I might make some "mock" bearings out of nylon for test fitting. I don't want to press in the real bearings until everything is ready for final assembly after anodizing or powder coating. I'll get some more pics once I mock up the front end, which includes lacing up the wheel.

And... I think I might be ready to start making triple clamps. I think I'll do them on the CNC. Looks like about $60 worth of material. I think it needs one slab of 1.5" aluminum and another of .75" for the top. I think it will be fun to do that programming on our old school CNC-converted Bridgeport.

Dave

[Syscrush]

NOICE!

[gsnorcal]

Progress has been slow. Started doing some *real* work.  

I finished the hub!!! Here it is, installed.







I started lacing the wheel, but I need to drill out the rim to accommodate the larger .281" nipples that I got from Buchanan. Gotta go find the right bit.

I also started working on the engineering drawings for my triple clamp. We'll start that CNC project next week, I hope. I'm gonna stick with the stock 400's offset. Slow bike, fast steering 

Dave