Topic: CB400F Cam Chain Adjustment Bolt

[grcamna2]

That is great prep work w/ those containers Ernest T.

[Ernest T]

I am putting it back together and now I'm having an "oh #$%*" moment.  I have the crankcase back together and am ready to put the shifter, oil pump, etc back on.  I put two dowels between the top and bottom halves, number 17 on the fiche, which are outside of cylinder 1 and 4.  I didn't put a dowel at the back end of the crankcase and wonder if I should have.

According to the fiche, there are 8 dowels in the crankcase.  There are two dowels which go on the left side to align the left side cover, nr 15.  Then there are four nr. 16.  Two obviously align the alternator covers and two go into the top of the crankcase to align the cylinder with the top of the crankcase.  The one I'm worried about is labeled 16 in the second picture, I know one goes into the case near the big studs for the cylinder, but in the picture it could be between the halves at the back end of the motor.

I think I've accounted for them all, but I'm not 100 percent sure.  Does that sound right?

[Ernest T]

I sure hope I don't have to take this back apart this week.

The first thing I did was turn the top half upside down and transfer the transmission from the old case to the new cases.  That was simple and pretty foolproof.  Its sorty fiddely because you have engage the shift forks with the shift dogs on both sets of gears.  I also replaced the crank, countershaft and transmission seals at that point. 



Then I installed the new main bearings into both halves making sure that they went into the right places because they are backwards at that point (since the case is upside down).  I coated both sides with assembly lube per the manual.

After that I wrapped the primary chain and cam chain around the crank and dropped the crank into top half by holding on to the primary chain.

Then I installed the cam tensioner rod, springs, and adjustment bolt and nut.



I decided to replace both main bearings (which are in the bottom half) so the first thing I had to was replace the left side bearing.  It sits in a machined cavity in the case and is held in place by a large circlip.



I drove the bearing in with a very large socket so I was only bearing on the race.  The bearing had been in the freezer for a week so I was hoping it would slide in fairly easily without heating the cases and it did.





Then it's a simple job to insert the circlip. 



You have to finish installing the main bearings and primary drive after the cases are assembled so I prepped the cases by cleaning the gasket surfaces with simple green and solvent to degrease them.



Next I put thin coatings of Yamabond on both halves.  I put a thin bead on and spread it with a popcicle stick.  here's a pic in the middle of the process.  The coating ends up really thin and I removed as much as I left.  I wiped up any that ended up inside the cases before assembling the halves.



Then I installed the bolts from the bottom and torqued them, then flipped the cases and dropped the top bolts in and torqued them to specs.



Once the top and bottom were back together I could install the primary drive parts inside the primary chain and install the remaining main bearing and primary shaft.

A spacer goes in here, but it has to go through the cavity for the main bearing before you install the bearing.



Like this



Then you install the other main bearing.





And finally insert the primary shaft.



I sure hope I don't have to take this apart and install a dowel in the cases.

[Ernest T]

I don't think I missed a dowel, I found this picture of the disassembly and it doesn't look like there was a dowel in any of those bolt holes at the back of the case.

[Ernest T]

I think there is a dowel hole on the top left corner, behind the gear.  Damn.  It's not much work to take it apart except for the sealant.  Hopefully it'll come off easil since its new.

[Ernest T]

Looks like I didn't miss any, I fished the old cases out of the trash and there is no place for a dowel except where I put them.  Whew!

[Ernest T]

I took a few minutes after work and started putting the gearshift mechanism back together.  I've got lots of parts and pics of them installed, but I couldn't decide where to start.



I decided to start with the star attached to the shift drum. 



This pin goes into a hole in the star to index it.  After I installed it, I realized this should have gone on first, but luckily it will fit even after the star is installed.





Then I realized, the two cams wouldn't fit with the big washer installed on the end of the star so I took it off and installed the cams..



Then I put the big washer back on.



Next I installed the kick start shaft.  It goes here and the end of the spring gets inserted into the hole in the case.









Then I installed the stopper and shift shaft.

Next I installed the primary gear that engages the clutch. It's in the lower right in the picture.





I think this is right, but I won't be able to check it until the cylinder is installed and I can rotate the engine.

I also took the oil pump apart and measured the clearances, they are in spec.  I replaced all the o-rings, including the one Honda doesn't sell.  I ordered a 2X40 mm vitton o-ring  from an o-ring supplier--it's the brown one in the picture. 





Then I installed the oil pump in the left side of the engine.

[Ernest T]

I finally picked up the head and cylinder from the machine shop.  I got all four cylinders and the head rebuilt for $81.50.  All the guides were good, they replaced the intake valve stem seals and lapped two valves to improve the seal.  All four sets of valves passed an air check so it should be good to go.  I'll check the ring end gaps before reinstalling the cylinder and head Saturday.

[Ernest T]

Well damn, I'm going to have to buy new rings, the end gaps are too large.  The max is .006 and I've got .010-.015 on most. I doublechecked the bore and they are all under the max size so these rings are just worn.



The cylinder looks good though.



A picture of one of the valves that were lapped. Notice the other valvve?  My machine shop does good work at a good price, but they don't do anything unnecessary to making it run good.   



I am working on supports to make it easier to drop the cylinder onto the pistons.

[Ernest T]

I'm getting close to putting this back in the bike!  I haven't torqued anything because I had a question about o-rings between the case and cylinder.  Once I'm sure I'm good,  I'll torque the ehad and reassemble the cam.

These orange o-rings seal the cylinder spigots to the case.



I put the pistons (with new rings) on the rods and installed the small clips that hold in the wrist pins.  The cloth keeps the clips from falling into the case if I drop them.



First I tried to use these wooden blocks I made to hold two high pistons square while I dropped the cylinder on to them.  That worked well.



But, the outside pistons were so low I couldn't get the cylinder down any farther and get the hose clamps off so I had to back up and start over.  I rotated the crank so the pistons were all the same height and put hose clamps back around the rings.  The head went down over the pistons pretty easily this time.



The cylinder on the case.



Before I installed the head I replaced these valves and four oil seals.





Case, cylinder and head reunited!



There are two oil pipes in the head that lube the valve rockers.  I replaced the o-rings and these rubber supports.  The new ones were supple, while the originals were like hard plastic.





New carb boots, o-rings, and screws to make sure the intake doesn't leak.

[Ernest T]

I finally got most of the engine buttoned up.  I installed new acorn nuts and copper sealing washers.





I installed the new carb boots so when I install the carbs they won't leak.  It also seems easier to install carbs when the boots aren't harder than a rock.



Once that was done it was installing the cam chain and timing the cam and crank.  These lines are supposed to be lined up with the top of the cylinder when the T is lined up with the timing mark.  Here the mark appears to be about one tooth off.  Its pretty easy to adjust by just pulling the chain off the sprocket and moving it forward one tooth.





New tensioner and slipper.



Installing them is pretty easy, just turn about 90 degrees and insert until it engages with the horseshoe under the crank. 



You want to make sure this tab is outside the tensioner tunnel otherwise it won't flex.



Then you install the top cam tensioner bracket.

. 

Here's the new cylinder head cover gasket installed in the cover. I just use wheel bearing grease to hold it in place until its bolted down.



I'm not ready to do a frame off restore on the bike, I just want to be able to ride it so I degreased the frame and am just going to reinstall the engine.  I'll work on other things as I go along.  I retire in a year and after I get settled in the retirement home I'll do this right.



The engine is light enough at this point that I can pick it up and place it in the frame by myself.  After it's in the frame I'll install the rotor. clutch and carbs.



I had a few other parts to source, the o-ring around the oil pick up was broken and it wasn't available from Honda, but I found one at Northeast vintage Honda parts.  I also need a few other odds and ends.  Once I have them together I'll put everything back together.

[HondanutRider]

I finally got most of the engine buttoned up.  I installed new acorn nuts and copper sealing washers.

I thought I had seen in another discussion, that copper and aluminum (the alloy primarily in our motors) is a bad combination and will lead to excessive oxidation and interaction between the two parts.  Aluminum washers are the desired parts I thought...perhaps I'm wrong and others can better comment.

[jessezm]

The stock washers are copper.  I think that discussion was related to the use of copper anti-seize and stainless bolts?  I could be remembering wrong, though. 

By the way, Ernest, awesome photo diary, thanks for sharing!  I'm sure it will be useful to others rebuilding their 400f or 350 top-end for the first time.

[HondanutRider]

The stock washers are copper.  I think that discussion was related to the use of copper anti-seize and stainless bolts?  I could be remembering wrong, though. 

You are likely correct and I was getting the facts mixed-up.  Does that mean that a copper washer for the oil drain plug would be OK to use instead of an aluminum one that is generally sold as Honda replacements?  I find that the aluminum ones get more chewed-up with usage than would a softer, more malleable one of copper.  Also copper washers for oil drain plugs are more commonly found in auto supply places.

[jessezm]

I guess I can't answer that on my own authority so take this with a grain of salt, but I would reason that unlike with other engine bolts, the drain plug gets removed so often (if you're keeping up with maintenance, mind you) that even if copper-aluminum interaction was an issue, it wouldn't be a problem at the drain plug since it doesn't sit undisturbed for a long period of time.  Whether there is another compelling reason not to use copper there is beyond me.  It would be nice to be able to just use one from the auto parts store.

[Ernest T]

I think you can use whatever you want.  Finding the correct size copper washer might be harder because they are kinda an odd size.  The hole just fits the drain bolt and the width of the washer is narrower than one would nornally be for the opening.  An aluminum crush washer is pretty inexpensive.  Hell, most of the fastning on a motorcycle is accomplished by a steel screw or bolt in an an aluminum hole.  Corrosion isn't normally an issue anywhere.  BTW, I've used antisieze on stainless with no apparent side affects.  Might be a different story 40 years from now, but who knows.