Topic: CB400F Engine Rebuild

[jakec]

I'm going to document my engine rebuild here. This engine will be for the 400F I am restoring. The bike is just about all finished and assembled, just waiting for an engine.

Here's the bike (mine in the background)



Right now I'm stripping down this donor engine that I got last winter. It came with a clusterf*** of parts that made up maybe 70% of a bike. The engine was already partially stripped, with the top end and pistons, and most of the side bits removed. The PO said it had it needed a new shift fork, and he included a NOS one. Taking it apart I didn't see anything weird about the shift fork though.

Anyways, I'm doing this because the engine in my bike had a leak from the bottom of the crankcase, at the front left boss where the engine attaches to the frame. There was JB weld on there and the bike would leak when it was hot. So I got this engine as a donor to mostly use the cases, and I will use all my nicest parts on it. In the end if I have enough to build another engine that would be cool.

I just split the cases. This is my first rebuilding an engine so I don't really know what I'm looking for in terms of wear. So far all the gears look like they have nice teeth, and the bearing/shaft roller surfaces look nice and not scored up.

Quit notes from taking the cases apart:

This small dowel fell out when I split the cases. As I was gently shaking them apart this part fell on the table:



Cam horseshoe looks pretty good although there is this chip in the part that receives the slipper:



Finally, it looks like the cam adjustment screw broke off in the case:



Right now my plan is to remove everything from the cases, and then clean the cases and get them vapor blasted. Then I will start rebuilding.

[RAFster122s]

Fix any broken bolts before vapor blasting of course...
Clean out all the screw holes and run a tap through/in them all to ensure they are swarth free once back from vapor blasting. Is Nils going to blast the cases for you?  He does fabulous work.

[jakec]

There is a bike shop near me that offers vapor blasting services, so I had planned to use them. I've seen the heads on the bikes they worked on and they look great.

[jakec]

I am watching this guy's videos to get an idea of what's coming. He lists parts to replace: "Gasket Set. Rings, pistons and associated pins and clips, primary chain, cam chain, big and little end shells, new style cam tensioner and any other parts that show wear."

https://www.youtube.com/channel/UCdA9cmik8sy0-JM2KDh_e-g/videos

I have a lot of questions:

The first thing he installs in bearings for the connecting rods and crankshaft. Is it always necessary to place these, or can you reuse the originals if they aren't worn? It looks like they are pretty pricy and you need about 16 total of these half bearings.

He also installs a new cam chain but keeps the original primary chain. Would it be necessary to replace cam or primary chain? Is there a way to measure the chains to see if they're ok?

After installing all of the shafts in the case upper he installs a new metal cam chain horseshoe, citing the damage on the lead edge of his. I noticed in my photos it also looks like there is some wear on the lead edge of my part.

Another question that I had which would be relevant later, when you have the cylinder vapor blasted I assume you need to remove the barrels, and I've read you can do that in the oven here, how do you get them back in? Oven again? But then how can you be sure they're flat? And if they are worn, you need to have them honed and then you need larger piston rings?

[RAFster122s]

Buy some plastigauge to check your clearance on the bearing shells. They will tell you if you are in tolerances or close to needing or need to replace the bearings.
Cam chain I would recommend you change unless the bike has less than 10k miles and it measures OK.
Primary chain should be changed if 30k or more miles if I recall the advice correctly I was given.
 Are there measurement guidelines or inspection guidelines in the shop manual for the primary chain?

Should not need to pull the cylinder liners on the cylinder block.

Show some pics of your cam chain horseshoe.

A machine shop can measure your cylinders properly to see if you need an overbore.
Drop off the pistons marked with each cylinder.  They can measure your pistons and cylinders and give you measurements for them so you tell if the cylinders are round. 

Not just any machine shop is going to be able to bore your cylinders keeping the correct tolerances. Many will claim they can, but results can be disappointing. The 350/360/400 are pretty tight tolerance motors. The size is sometimes a limiting factor for some shops as the pistons are much smaller than the typical auto motors so they just do not have the equipment.

[awrawr]

Liners slide back in again very easily when the block has been heated in the oven. Never had a problem getting them in to the full extent.

[trigger]

This thread shows a the difference between a new primary chain and a worn one. Always a good idea to change the primary chain and primary rubbers, unless you want to strip it down again 
Link >>> www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

[bryanj]

Shells must go back in EXACTLY the same position they came from, once removed there is no way oy telling the colour code or size.

[RAFster122s]

This thread shows a the difference between a new primary chain and a worn one. Always a good idea to change the primary chain and primary rubbers, unless you want to strip it down again 
Link >>> www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Post 203 shows a good hyvo chain next to a worn out one...

[jakec]

Post #203? How do I find that? Thanks!

[RAFster122s]

Thanks Calj, my tablet was not letting me capture the single post...
David

[jakec]

Thanks! I've been aware of that thread but haven't joined the forum yet so I can't see the images. Will do.

[jakec]

Buy some plastigauge to check your clearance on the bearing shells. They will tell you if you are in tolerances or close to needing or need to replace the bearings.

I will, the service manual that I got (here on the forum) is missing the middle third for some reason, so I am missing all the parts that follow splitting the case.

Cam chain I would recommend you change unless the bike has less than 10k miles and it measures OK.
Primary chain should be changed if 30k or more miles if I recall the advice correctly I was given.
 Are there measurement guidelines or inspection guidelines in the shop manual for the primary chain?

See above, I need to look around for a more complete manual. I did NOT keep track of which shell went in each groove, but I did separate the shells top & bottom. I figured that was enough, and then I would match them up by the letters on the crank?

Should not need to pull the cylinder liners on the cylinder block.

How can I clean the gasket from the bottom of the cylinder block with the liners in? I was going to pass over the whole thing with sandpaper on a flat piece of glass (like all other mating surfaces).

Show some pics of your cam chain horseshoe.

A machine shop can measure your cylinders properly to see if you need an overbore.
Drop off the pistons marked with each cylinder.  They can measure your pistons and cylinders and give you measurements for them so you tell if the cylinders are round.

Not just any machine shop is going to be able to bore your cylinders keeping the correct tolerances. Many will claim they can, but results can be disappointing. The 350/360/400 are pretty tight tolerance motors. The size is sometimes a limiting factor for some shops as the pistons are much smaller than the typical auto motors so they just do not have the equipment.

I think I may do a 466 kit since I am in here. I have found a shop near me that has been used to mill 400 engine parts through a thread on here - http://forums.sohc4.net/index.php?topic=137025.0

[jakec]

I just read the first 10 pages or so of the sohc4 UK thread, the parts that are relevant to my progress so far at least. I'm really impressed with the speed that they moved, having the cases closed back up in about a month and  half, blasting & painting the cases and all. Right now I am cleaning my cases (which is something I really don't enjoy doing, scrubbing and breaking gloves).

I did not know that you were supposed to keep all 10 bearing shells separate, I've read threads on here where someone's shells read AABBB or something like that, I just kept my shells separate by top & bottom and I thought I would look at the crank and put them back in the case in order based on that? If there is no way to know where they go then how could you install replacements?

The video series I was watching, the guy  just replaced all shells with new. I saved some screenshots from threads below for my own reference later.

I need to get the designations for the crank journal - J and the case. Then I can reference the table to know the position of the bearings. But the wisdom is that due to wear putting them in an incorrect journal (even if correct designation) would be bad?

[RAFster122s]

Yeah, bearing shells have to stay with their respective journals...best to research and read several good manuals on a rebuild or watch good videos. You aren’t alone, others have done the same thing.  I once mixed up pushrods on an auto motor I was rebuilding when the cardboard they were slotted into was knocked off the bench and they went flying out of the slots. Oops.


 Not sure what to tell you on what to do now if the shells are mixed up as you will never get them back in their original places.  Did you see the 350 rebuild YouTube video a member posted recently? It is a very good video, well done and informative.
Maybe someone like Calj or MRiech can advise you what to do about the bearing shells.
David

[RAFster122s]

Does the U.K. site have a complete factory manual pdf?

[mattsz]

I will, the service manual that I got (here on the forum) is missing the middle third for some reason, so I am missing all the parts that follow splitting the case.

See above, I need to look around for a more complete manual. I did NOT keep track of which shell went in each groove, but I did separate the shells top & bottom. I figured that was enough, and then I would match them up by the letters on the crank?

The factory service manual for the 350/400 is pretty slim - compare it to the 750 to see what I mean.  In both cases, assumptions are made about the mechanic's knowledge of working practices.  Neither tells you that you should keep track of the bearing shells.

Are you missing the section on removing the crank, which begins on page 31 of the factory manual?  If so, I can send you what I have.  One of my download copies has other manual pages, including a Honda "common service manual" printed in 1988, which covers many models, I guess, but it's not made clear which ones.  This one, however and FWIW, does instruct you to "mark and store the bearing inserts to be sure of their correct locations for reassembly."  Doesn't help you now, though!  Let me know if you want copies...

Yeah, bearing shells have to stay with their respective journals...best to research and read several good manuals on a rebuild or watch good videos.

Which "good manuals" do you recommend?  The factory manual is not very detailed; Haynes and Clymer seem to get bashed a lot for incorrect information.  What else is there?

Did you see the 350 rebuild YouTube video a member posted recently? It is a very good video, well done and informative.

I didn't see any "recent" 350 rebuild videos on YouTube - can you be more specific about which one you're referring to?

[RAFster122s]

http://forums.sohc4.net/index.php/topic,179538.msg2083556/topicseen.html#new
A 350K race engine rebuild, 2 hours or so in length.
Motorcycles do not have a ton of books out there on maintenance that I am aware of...most of my motor knowledge comes from cars I have owned and maintained and those I have studied when interested in and considering buying...
I generally dislike Clymer but, I do not mind Haynes...
 I learned a lot about motors from rebuilding and maintaining old Volvo’s from the 60s and 80s. I had a few mentors which helped a lot. Books like Vizzard’s performance engine rebuild book on the Mini Cooper and a huge tomb about the Mini Cooper A-series engine maintenance and rebuild manual that I bought around 2008 timeframe...don’t recall the authors were excellent and ‘Autobooks’ Model specific manual on a 60s Volvo I used to own. Bentley’s made a great manual.
Chiltons had decent motor specific series for Chevy and Ford motors but I did not like their manuals as well. Local libraries are likely to have Chilton and some Clymers and possibly Haynes manuals.
The factory manuals and parts diagrams I now find to be decent and this forum and YouTube tend to be my go to for the motorcycles.
Sorry I am not more helpful with specific titles.
Buy HondaMan’s book on the 750, much of it applies in general knowledge and while it is dry sump many of what Mark teaches in the book can apply to other SOHC4s of the era.
David

[mattsz]

Thanks RAF122S - I haven't paid much attention to non-four work.  I'll check it out.  Thanks for the book info as well, I assumed (hoped?) that you had some motorcycle-specific manuals I hadn't heard about...

[jakec]

I just took a look at the PDF available on the forum here and I think I am missing pages 25-34, which is everything after splitting the case. I have a printed copy at home though so it's possible that something happened when i printed it out.

Like you said though, it doesn't say anything like keep the bearing shells in their respective races or you will die.

Maybe someone can chime in here, it sounds like worst case scenario I would have to buy all new shells to be safe?

[Tim2005]

I expect some of us have got away with it over the years. However, first your ought to plastigauge the shells anyway with them in your best guess locations. There's no point worrying about them being swapped around if they are all out of tolerance anyway, and if they are all inside tolerance then it'll give you increased confidence with running them.

[mattsz]

Maybe someone can chime in here, it sounds like worst case scenario I would have to buy all new shells to be safe?

If you can find them...

Sorry, but I've heard stories...

[jakec]

I'm cleaning my cases today and had some weird results. I was previously using acetone which was working, but I had some hard to reach areas that I couldn't get with my tools. So I followed advice on the forum here and used ZEP degreaser. I soaked the parts for about 5-10 minutes each and then rinsed with hot water. The first thing I noticed was that the ZEP solution seemed like it lifted the remaining grease off the parts and then redistributed it evenly everywhere else. So I had these cases that were pretty clean, and they came out with a film of grease all over, making them dark grey.

I dumped the dirty initial batch of degreaser and poured more and rinsed them again.

Then I did next step, put them in the dishwasher with some dish detergent. They came out of the dishwasher with grease still pretty much the same, but they have this residue now I am guessing is from the detergent?? It rubs off, but now the inside and outside of my cases are greasy and white-bumpy, I'm kinda confused and not sure what I should do now.

This is the inside of the case. Before it was all but perfect, clean shiny silver color.



Outside



Photo showing how the white stuff rubs off, and there is grease underneath

[Kelly E]

I clean my stuff with solvent and rinse with brake cleaner when I want it really clean. I don't have a parts washer yet so I use a big SS steam table pan with a pan of clean solvent to dip the brush in. I buy the solvent in five gallon buckets from the parts store.

[bamacb]

If you are going to vapor blast the cases why worry, it will be cleaned up then.