Author Topic: A 1975 CB400F 102.000 km (65000 mi) complete engine rebuild (Read 46251 times)

supersports400 · « **Reply #50 on:** March 30, 2010, 01:47:19 PM »

And the bearing surfaces :

andy750 · « **Reply #51 on:** April 26, 2010, 06:38:08 AM »

Bump for a great thread. If you feel the same way as I do, give Jensen some encouragement for documenting a meticulous build. It takes a lot of time and effort to do this....anyone else?

I for one am looking forward to seeing this to completion.

cheers
Andy

fastbroshi · « **Reply #52 on:** April 26, 2010, 08:00:20 AM »

Bump - the guy took pictures of his bearings for Chissakes.

Kwality · « **Reply #53 on:** April 30, 2010, 07:07:41 PM »

Me three!

Enjoying the build. Very interesting.

jacquesleclochard · « **Reply #54 on:** May 30, 2010, 03:28:00 AM »

Bump.

Lukt het nog?

strynboen · « **Reply #55 on:** May 30, 2010, 09:13:50 AM »

vi vil se mere,,,
hope you vent back vith more intresting detals,,its big inspiration to me..have self a 400 vith 100,000 km on klock
så have similar problems...

fasturd · « **Reply #56 on:** June 01, 2010, 02:03:51 PM »

Hey guys I think he was having some time difficulties keeping up with postings, building and life in general. I think he will post again but maybe a little less often. Great info and very detailed!!!

+1 on the bumps!

supersports400 · « **Reply #57 on:** June 07, 2010, 05:05:01 AM »

Hi,

In the mean time I tracked down a nice low miles gear box with a good set of gears. I measured all the parts, throw in some new parts and did rebuild the gearbox. A complete overview of that process will be pictured later, I first start with the cylinder head. I flattened the head, just for sure, now it's straight within 0.005 mm for sure, but looking at the milling face I guess the head was straight already. As modern patrols are lead free, and I don't like to add lead or something like that in my tank every time, I cut the valves at 45 degrees and faced them at 1 mm. Like I wrote earlier, all the valve are new but the guides are original. The play guide - valve is within specifications, so I decided to let them in.

Jensen

andy750 · « **Reply #58 on:** June 07, 2010, 05:06:34 AM »

Welcome back Jensen

and enjoying these quality pics!

good luck
Andy

fastbroshi · « **Reply #59 on:** June 07, 2010, 08:20:52 AM »

What's with the little logo on the valves? My 550 valves had that too. Made by Mitsubishi?

supersports400 · « **Reply #60 on:** June 07, 2010, 11:16:26 PM »

Hi,

Yes, it seems like a Mitsubishi logo, all the valves in this head have the same logo. A few years ago I got a lot of NOS sohc4 parts, most of them for the 750, but some for the smaller engines. I got the valves from those pile of parts.

Jensen

supersports400 · « **Reply #61 on:** June 08, 2010, 06:24:54 AM »

Hi,

While assembling the engine I took many pictures, and close ups. The inspection of the parts can be done behind the computer after measuring the parts for a within specification / out of specification decision. Actually I took pictures of every single part, I do that always when I restore / rebuild the engine. I label the pictures with the part number and the results of the measurements, the pictures labeled with an F (fault) should be replaced. This set of pictures marked with an F is direct input for my search list. When the (new) parts arrive I can directly compare the parts and decide it's the wrong or right part. With the older Honda's there are many different parts used in one type of engine, sometimes these parts have the same part number, or the part number on the particular part is written down wrong somewhere in time.

The above sequence seems to be a lot of work, but there's always a moment when you think, glad I did it. I never regraded this way of working.

Like I wrote earlier, I replace the complete cylinder with a new one, including NOS standard pistons, but never the less, it still is interesting to look at the pictures of the pistons, rings and pins.

When you look closely to the piston pins you can see that the wear is not linear over the whole area, in fact the piston pins show asymmetrical wear. My assumption is that this is due to an misalignment of the crank in the cases or cylinder to cases, but with this minimal damage on the pins after 100.000 km, it's not something to worry about. The conrods were within specification, so another reason to let it as it is. Of course replacement of the pins is necessary.

The piston rings are all in one piece, but do have a lot of blow by, so replacing the rings is a must (logical).

laminarflowone · « **Reply #62 on:** August 05, 2010, 07:27:53 PM »

Wow, this is very helpful to me because I am trying to rebuild the engine of my CB750. If only I could download some of your expertise into my head...

strynboen · « **Reply #63 on:** August 06, 2010, 11:00:52 AM »

hey i have a bit step back..my gear bearing vas broken and one gear shoves problems..are both bearings same type and tolerance A 5205..

...klik on pics to get bigger pics

supersports400 · « **Reply #64 on:** August 09, 2010, 05:26:59 AM »

Hi strynboen,

Sorry for my late reaction. I think you mean the p/n 91002-286-008 don't you ?
Yes, these bearings are the same, but......, this bearing is pressed on the shaft by Honda.
There's only one way to change this bearing according to Honda, and that's buying the whole shaft as a unit.

But, you can press it off, and press a new one up again, but, you have to press the bearing on the same location as the old one. Measure precisely where your's is (within 1/10 of a mm), make a mechanical stop to place into the space between gear and shaft, and press a new one onto the shaft. You have to do this right the first time, there's on second chance.

The gear in the last picture is heavily pitted, start looking for a better one. Always replace the gears as a pair, as where one is pitted the other one is pitted too. This pitting are caused by cold welds, and most of the time it's the oil to blame.

I know you have strong feelings against using synthetics, maybe you should to re-consider using these oils.

If I were you I should open the oil pump, if you're lucky, these parts stayed out of it, but I guess, it will show the same wear as mine, and maybe considering a pump rebuild.

Jensen

strynboen · « **Reply #65 on:** August 09, 2010, 06:33:21 AM »

hey..i have no hurry..så its ok..,,and nice to now vhy there vas no number on that bearing..
i vill press it on littel by littel ,,to it come to fit that lock rill..have an littel hyd press..and make some tools..to fit..
have to chek clm.nl..for gear parts..dont think i can find used parts in europa..all bikes have run atleast 60,000 km..
i hope to press the bearing and distans piace on in small steps.and trying it in block..if it have to be heated for mont..i have to do it in one step....have to get that bearing first..il be back...

supersports400 · « **Reply #66 on:** June 19, 2011, 10:42:04 AM »

Hi,

It's almost a year ago that I posted the last post. In this year a lot of things happened. One thing is that I lost two people I knew for a longer time, both related to the motorcycle hobby. My engine is lying is still in parts, waiting for the right moment to put together. In the mean time I got a CB450 K0 (black bomber), and all the CB450 and CB500T parts someone could wish for. I rode the bomber a lot last year, and didn't manage to wrench a lot, I think I wanted to enjoy life and take the bikes out more often instead of wrenching all the time. Sometimes people forget why they have a motorcycle, perhaps I did too.

The last few months the weather was perfect, and I rode a lot. But now it seems that that autumn has begun, so I decided to start wrenching again, and the CB400F is the engine which is blocking my working space, so that will be the first one to work on. Soon I will continue this ongoing story on one of the nicest bike I know and have.

Some pictures of the bomber included,

Jensen

strynboen · « **Reply #67 on:** June 19, 2011, 10:54:38 AM »

glad for you back..i have not faundn gear parts..for my 400..but have get an cb 77..and startet on the engine..an singel cam engine..older type then the bomber engine..i think

supersports400 · « **Reply #68 on:** June 19, 2011, 11:09:11 AM »

Hi,

Yes, that's a nice bike. If you need ANY help with that bike, please let me know. Wrenching and working for over 10 years on these CB72 / 77's made me some kind of specialist. I have tons of parts too. I also have more then one spare transmission for the CB400F, maybe I can help you with trans parts.

Jensen

strynboen · « **Reply #69 on:** June 19, 2011, 11:23:53 AM »

great to hear..i will send an pm..when i have tjekked aut hvat missing..have to klean and test all parts first..ist an interisting engine..like that vay the ignision regulator goes thrugh the cam..and chlutch push pin goes thrugh the finale gear..and kick start sistem..just honda can do it like that..think they have looked at nsu in germany..its looks like germen vay of thinking,,and japanese perfektion

fastbroshi · « **Reply #70 on:** June 19, 2011, 02:47:21 PM »

That's a good looking Bomber Jensen, that bike is up there on my list.

RickB · « **Reply #71 on:** June 19, 2011, 03:49:20 PM »

Good to hear from you Jensen. Thanks for the update.

brewsky · « **Reply #72 on:** July 15, 2011, 04:04:07 AM »

Just found this thread, Jensen, it is good and keep it up.

Haven't been on here much lately, but it's time to play with my 750 again.

I recently saw a local ad for an "original" running 350F for $800.00, but passed as I am really waiting for the right CL450 to pop up.

andy750 · « **Reply #73 on:** July 15, 2011, 04:57:36 AM »

Glad to see you are back at this Jensen. Really like the bomber and I bet its fun to ride. Its always good to be reminded why we ride motorcycles.

good luck
Andy

supersports400 · « **Reply #74 on:** July 16, 2011, 03:56:23 PM »

Hi,

At last, my desk is free of stuff, you would be amazed how attractive an empty desk is to parts. they were all over the place.
Thanks for the kind words. Tonight I opened all the boxes with the CB400F parts, and displayed them on the desk for my self. Now I have to decide if I want to paint the upper case, or keep the patina that has been build up for all those years. Same with the head and covers. The one thing that bothers me is that I have a NOS cylinder that looks great, but the rest has it's patina, and I think the contrast is too big, so I think I have to let paint the case.

Jensen

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Author Topic: A 1975 CB400F 102.000 km (65000 mi) complete engine rebuild (Read 46251 times)

laminarflowone