Topic: CB400F Cam Chain Adjustment Bolt

[Ernest T]

Those shells are damaged by dirty oil/crud and do need replacement, forget the measuring you need to use plastigauge to get it 100%

That's what I thought when I saw them.  I have two options, use the crank that came in this engine or move the crank from the other engine.  Either way I have to measure  the crank and inside bearing  diameter to determine which bearings to order.  The crank that came with these cases looks pretty good , but I need to disassemble it to measure the crank bearings before I decide.

[bryanj]

Unless you have factory air gauges you will never be accurate enough with measurments, only way is plastigauge mate

[Ernest T]

Okay, explain to me how to use the plasticgauge to figure out which bearings I need to order.  I put the plasticgauge between the bearing and crank, then torque the cases.  Take the cases apart, remove the crank and measure the clearance. Let's say its .006.  The max clearance is .003, what bearing do I order?  Does the fact these bearings are already worn make a difference? 

[Ernest T]

I now have a cylinder gauge which is accurate to .0001 if that matters.

[bryanj]

Unless you know which shells you have you will have to buy a pair of known colour, then using old ones in the other places repeat the plastigauge 5 times moving the new shells to each location.

OR

Put in the tightest shells you can get and run the engine in carefully for 4-5,000 miles with oil changes every 1,000 after the initial one at 500

[grcamna2]

I now have a cylinder gauge which is accurate to .0001 if that matters.

ErnestT,
              I like to take a look at that cyl. gauge;would you post a picture of it ?
Where did you get it ?

[Ernest T]

I now have a cylinder gauge which is accurate to .0001 if that matters.

ErnestT,
              I like to take a look at that cyl. gauge;would you post a picture of it ?
Where did you get it ?

This is the one I bought.

http://www.sjdiscounttools.com/fow74-646-401.html

[grcamna2]

Ernest T,
                I looked at the link; I never owned an inside mic but have always wanted one...;does it give you exacting measurements as you measure your cylinders at different depths & widths.I guess what I'm asking is,for example,will it give you readings in your cylinders to tell you how out-of-round they might be ?

[Ernest T]

Ernest T,
                I looked at the link; I never owned an inside mic but have always wanted one...;does it give you exacting measurements as you measure your cylinders at different depths & widths.I guess what I'm asking is,for example,will it give you readings in your cylinders to tell you how out-of-round they might be ?

You can use it to do that by taking a measurement then spinning it 90 degrees and taking the measurement again.

[Ernest T]

You can also buy a set of these:

http://www.ambientweather.com/gemis986.html

and a suitable outside caliper which is probably cheaper.

[Ernest T]

I have a gasket set (minus the damaged head gasket) on hand and engine seals, cam chain, cam chain slipper, cam tensioner, 1 each set of brown and yellow main bearings, primary dampers, and a bunch of misc hardware incuding all the rubber parts in the engine on order.  Hopefully I can tear down the good engine and rebuild it in the new cases over Christmas break. 

[Ernest T]

I'm working on the engine to fix the cam tension issues.  I've decided to tear it down in the frame because it's too heavy for me to lift it out by myself.

I have cases ready for the rebuild.



The opening for the countershaft has scratches in it.  They don't go all the way across but I'm thinking I could fill them in.  Do you think that is necessary or can I ignore them?



Lots of signs of poor maintenance on the bike.  It has the wrong clutch cable--it doesn't even screw into the engine case.



But it does look like someone put a new rotor and stator in fairly recently.





The carbs worked fine, but they really could use some cosmetic work.  I'll fix the corrosion issues and replace the o-rings inside.









Once I got the cylinder head off, I could see the cam chain was very loose, I could hear it rubbing on something inside when I turned the crank to pull the cam chain sprocket.  I could also pull it off the sprocket with my finger.  The tensioner definitely isn't working.  Both the cam tensioner and guide are very worn.









I got 7 out of 8 exhaust studs easily and the last one broke.  Figures.

The cylinder is stuck, it's gotta be at the base gasket because it turns over very easily.   I quit today before I broke something from impatience.

[grcamna2]

Nice work Ernest T  and great pictures too.

[Ernest T]

I smacked the bottom of the cylinder with a cold chisel ground down to approximate the shape of the cylinder.  It just took a light tap and the cylinder was free.  However, this was as far as it would go.  The pistons were free, but it felt like the middle studs were holding it up.  After half an hour of reefing on it, I got a wooden drift and smacked it on the bottom a few times.



After a few taps, this fell out of the cylinder.





It's some kind of plastic putty that was put into the slot in the front of the cylinder where the studs pass through the fins.  You can even see the the person's finger prints who put it there.  Nothing about it in the manual.  A few taps with a small screwdriver and it was out and the cylinder was free.

This was where it was, four of them.



Now I can lift it out of the bike and put it on the bench.



I measured the bores and all are in tolerance so I'll just have it honed.  The rings look good and it wasn't burning oil so I'll reuse them.  The max outside measurement is 2.012.

Cylinder            measurement at the top       Measurement at the bottom
1                       2.006X2.006                         1.994X2.004
2                       2.007X2.006                         1.994X2.009
3                       2.008X2.007                         1.986X2.005 
4                       2.005X2.009                         1.996X2.007

All four pistons were above the 2.002 minimum.

I'll split the cases and move the transmission to the new cases and then check the crank and main bearings with plastigauge.  The head will go to the machine shop for a full inspection and minimum of new valve seals.
       
 

[strynboen]

some broke holes in to the cam tunnel..its not standart...but why...

[Ernest T]

some broke holes in to the cam tunnel..its not standart...but why...

What?  Don't understand.

[strynboen]

 there are broken holes in the cylinder blok

[jessezm]

there are broken holes in the cylinder blok

I don't think so--Usually you can see all the way through from one side to another on either side of the cam tunnel where that "putty" is.  No clue why someone would block them off like that...  It seems to me like you'd want air to pass through to allow cooling between the inner cylinders

[Ernest T]

I got it now.  No, someone filled in the passeges through the cylinder between the 2nd and 3rd pistons.  Don't know why they'd do that.

[Ernest T]

Today I finished stripping the cases so I could take them apart to look at the cam tensioner.  Here's some pics of the disassembly

Every bike I work on seems to need a different size flywheel puller.



I discovered that it's easier to break these philip's screws with vice grips, even with very little room like there is here.



This bike has one of the most complex gearshift linkage I have ever seen.



The primary chain is good.









Here's the problem.

The cam chain was really loose because someone had broken off the adjuster bolt and couldn't properly tension it.  Soon it was loose enough to rub on the horseshoe and then it jammed up and wouldn't move.



I can't even get the springs and adjuster rod out of the case.



It's hard to tell from the pictures, but 1 and 4 need replaced as they are scored.  Just for grins I moved all the shells from the old cases to the new cases and measured the clearance with plastigauge.  All except one set were in tolerance.

Then I measured the clearance on all five bearings with plastigauge by moving the one new set of bearings (green) from location to location.  Again, they were all in tolerance even though number 4 was iffy with a C.  I'm going to end up with CCCDC in the new cases.  Originally the motor came with CCCCB in the old cases.

All the crank journals are larger than the largest listed in the Clymer manual so there has been little to no wear on the crank.

This clearance is between 2 and 3.



The clearance here is is between .002 and .003



The clearance here is between .001 and .002.



This was the worst, really iffy 3 so I'm going to go up one thicker bearing.

[Ernest T]

I dropped the cylinder and head off at the machine shop today. I should have them back by the end of next week.   If everything goes well, they'll replace the valve stem seals and that'll be it.   I went through the gasket set and determined which o-rings I need that were not supplied and will order them tomorrow.

[grcamna2]

Ernest T,   
               Nice pictures w/ plenty of detail,I feel like I'm right there with you at the bench; and Great work.

[Ernest T]

I finally have all the parts to put the bottom end back together. 

The first thing I did was rebuild the starter clutch and replace the rubber cush drive.  I used new springs, rollers and caps.



I also was able to locate a new needle bearing and decided as long as I had it apart I might as well replace that too.



I also found a NOS neutral switch, the original worked, but the body was chipped.



Here you can see the new main bearing shells with engine lube on them ready for the cranshaft.  I put the transmission and primary into the upside down top half of the cases, then dropped the crankshaft on to the top half.



Then I installed the cam chain tensioner.



Then I did a dry run by setting the bottom case on the top half and inserted the primary shaft.  Everything looked pretty good.



I have some questions about the cam chain.  I ordered one from Honda and expected it to be an endless chain, but this is the way it came.



It's not a master link, but looks like one that should be peened.  However, only one of the pins will go into the link, the other won't go into either loose end of the chain,







What the heck can I do about it?

[Ernest T]

I thought I was ready to reassemble, but this damn cam chain has me flummoxed.  It's supposed to be endless and the pins are buggered and I wouldn't trust it.  As bad as I'd like to put it back together I've contacted the dealer and they are sending a replacement.

Here's how I keep organized.  Instead of putting everything in one plastic bag I put each subassembly in a small baggie.  Then, when I'm ready for reassembly I clean the parts and put them in a plastic bin ready to go. 

The big picture.



Each part gets cleaned in paint thinner.





Then it's put into a bin in the order of assembly.















These are all the bottom end pieces, when I can finally put it back together it'll go smoothly and I'll know it was done right because I won't have any left over parts.

[Ernest T]

I finally heard back from the machine shop.

They did an air test and two valves are leaking.  Then they disassembled the head and neither valve looks bad so they are going to see if they can lap in the valves and get a seal.  He said the valves looked too thin to grind so I'm hoping they don't have to recut seats or replace valves.

They checked the cylinder and verified my measurements--the bores are good, the pistons are in spec and the ring end gap is good.  He suggested just a light honing and no new rings.  He said they should seat just fine.

Still waiting on the cam chain.