Topic: Who's cam is it anyway?

[Lavis500]

So I'm in the middle of tearing apart my '73 cb500, and I know that a PO did a number of things that the most recent PO didn't know about, and I'm finding them all in my journey.  I have never done a build that was this in depth (normally just rebuild carbs and adjustments and silly little stuff).  I am on my way to the center of the block, as I have to replace my rings.  ANYWAYS, on to my question:  I pulled the cam today and decided to measure it.  My exhaust lobes all seem to be around 34.8 mm and my intake around 35.25  According to my service manual, exhaust lobe height should be between 34.53-34.57 mm with a serviceable limit of 34.45.  I would assume this to mean that anything smaller than 34.45 is excessively worn.  Now, the intake cam lobe is 34.93-34.97 with a limit of 35.85.    Why is the service limit BIGGER?  Does this lobe magically grow with wear and tear??  My measurements are less than the serviceable limits but more than the standard...  is this normal?  Again, I know that the PO has changed some stuff I.E. I happened to find a 15 tooth front sprocketwith the chain rubbing the case.     Also, FWIW my cam has "R3" stamped into it and underneath that it jas a molded "J."  There is a molded "5" on the opposite side of the shaft.  I don't see any "HM" or other honda markings at all.  Any answers would be appreciated!

Also, does anybody have any suggestions as to what else I should do while I'm journeying to the center of the block?

[Lavis500]

Bump.

Really guys??  Nobody?  Is it that I'm not making any sense, or am I just asking about something stupid?  All I want to know is if my cam is original or not as well as if it is serviceable.  Please, don't leave me in the dark; that's how we wind up with PO's who make really stupid mistakes!

[fastbroshi]

  I don't have a 500 but I'll try to help.  Your values (little simpler to look at this way):

measured lobe height:
IN: 35.25mm
EX: 34.80mm

What book are you using?  Have you checked your cam bearing journals with plasti-guage? 

[Lavis500]

I have a PDF version of what the Honda workshop manual for CB500/550 published July 20 1977.  Haven't grabbed the clymer yet as this has seemed to be pretty helpful until now.  The most confusing part of the whole thing were those specs:

IN: 34.93mm-34.97mm / LIMIT: 35.85 (mine measuring 35.25)
EX: 34.53mm-34.57mm / LIMIT: 34.45 (mine measuring 34.80)

I'll see if I can't glance at a clymer from the library until I can get one off amazon or something.

By cam bearing journals do you mean the runouts?  I hadn't read anything in the shop manual about plastiguage, but I've seen it on the forum a few times.  Can this be had at autozone, o'reillys, etc?  If so I can go grab one tonight when I go to rent a valve spring tool.

BTW while I'm in here:  I'm tearing everything down and going through everything since I had to replace the rings.  I don't want to split the cases as everything from the pistons down looks REALLY clean so far...  But since I'm replacing every other gasket and o-ring (and I'd like to replace every fastener) would it be suggested to split them anyways and replace the bottom end gasket?

Attached is a picture of my head.  Boxed in red is what I think you're talking about.

[fastbroshi]

Plasti-Gage should be available at any of those stores. 

I can't confirm the 500 cam is the same as the 550, maybe BryanJ will chime in here.  I'm thinking either you're misreading your PDF or it's translated oddly.  It's not physically possible for your cam to get bigger, so I don't know what to make of those numbers.

[scottly]

IN: 34.93mm-34.97mm / LIMIT: 35.85 (mine measuring 35.25)
EX: 34.53mm-34.57mm / LIMIT: 34.45 (mine measuring 34.80)

I'm guessing the wear limit of 35.85 is a typo: should read 34.85.

[Lavis500]

I suppose that makes sense.  That would make the difference between the limit and the minimum average .08mm for both of them.  The consistancy between the two leads me to agree with you.  Perhaps I should attribute the oddness of my measurements to the fact that I'm using a vernier caliper rather than a micrometer, though I wouldn't think it'd make much difference?  Not that I have any intensions of being lazy, it's just that I am only given a certain allowance of money towards tools for each month.  The wife doesnt want me spending ALL of our money...   

I just checked o'reilly, autozone, and walmart.  nobody had ever heard of a plastigauge.  

[scottly]

If you do the math, the wear limits are .008 less than the minimum spec, for both intake and exhaust, if you change the suspected typo. 

[fastbroshi]

I just checked o'reilly, autozone, and walmart.  nobody had ever heard of a plastigauge.  

Noobs.

[scottly]

Yeah, don't count on getting much technical advice from parts-counter jockeys..... At least not good advice.

[Lavis500]

Spent a good 15 minutes up and down the tools aisle... I'll see if I can't go back in the near future and double check; maybe I'll find a better auto store.

In the mean time I'm disassembling my head so I can clean off my valves.  Everything that was in the combustion chamber has a decent layer of carbon except for the cylinder walls.  They look surpisingly clean with the exception of a 4-5mm ring around the top of each.  The walls still have a decent cross-thatching pattern, but I think I'll still go ahead and give them a REALLY light hone just for good measure.

Any thoughts on splitting the cases?

[scottly]

Most parts-stores don't have stuff like plasti-gauge on display; it's just a tiny round length of plastic in a paper sleeve. You tear off a piece, lay it across the bearing you are measuring, and assemble the parts. Then you disassemble, and measure how wide the plastic was squeezed, with the scale printed on the paper sleeve, to determine clearance.   

[steamnjn23]

i bought my plastigauge at o'reilleys.  they offered red and green and for $1.50 per pachage i bought both.  only have used the green tho'

[754]

Dont go splitting your cases to change a gasket, cuz there isnt one..

 I think some of them parts store dont know Sh!t from Dirty  Pudding...

 To the uninitiated, the 1 1/2 thou clearance on a cam is HALF the thickness of a  human hair.. .. of course the colour of the hair matters, but we dont need to go there right now..

[fastbroshi]

In the mean time I'm disassembling my head so I can clean off my valves.  Everything that was in the combustion chamber has a decent layer of carbon except for the cylinder walls.  They look surpisingly clean with the exception of a 4-5mm ring around the top of each.  The walls still have a decent cross-thatching pattern, but I think I'll still go ahead and give them a REALLY light hone just for good measure.
Any thoughts on splitting the cases?

Did you happen to do a compression test before you took everything apart?  If not, measure your bore and see what you have.  I wouldn't split the cases if you don't have a reason to.  

[fastbroshi]

To the uninitiated, the 1 1/2 thou clearance on a cam is HALF the thickness of a  human hair.. .. of course the colour of the hair matters, but we dont need to go there right now..

nappy or straight?

[Lavis500]

The compression test is why I got into this thing in the first place.  My compression gauge read 128psi across the board.  I put oil in the sparkplug hole of one cylinder and it upped the compression to 150.  I figured I had to replace the rings...  weird enough though:  the rings on there right now seem rather sharp.  I would think old worn rings would be worn?

The other thing is I kinda stripped the first couple threads on my #1 cylinder spark plug hole with the d@mn gauge adapter...     I'm going to go from the other side with a thread chaser and hope I can save it...  if not then helicoil inserts would be on my horizon I suppose.  The good thing about my job in the army is I work closely with airframe guys, so I'm not entirely unfamiliar with things like that. 

**scratches at grime where the cases meet**  Oh looky...  no gasket!     If I change out all the hardware for the engine one bolt at a time then I should have nothing to worry about, right?  How does one go about changing out the long jug bolts?

Also, I measured my bore when I first pulled my jugs.  All cylinders read at just under or at 56mm on both the X and Y axis.

[fastbroshi]

  If they seem a little low you might put that down to the particular guage you used.  If they're even across the board I'd call them good.  Even good rings will seal up marginally better with a bit of oil. 

  The rings like you said weer still pretty sharp so they're probably good.  Don't even worry about taking out the studs unless you've got racing or turbocharging plans.  Since you've got the head off a helicoil for the spark plug hole should be pretty quick and easy.

[Lavis500]

No plans on racing, but this bike is from minnesota.  Everything has been subjected to harsh salty winters...  as a testament to how rusted this bike was, one of the nuts on a bracket for the highway bars was so rusted that the bracket bolt sheered in half AFTER using PB.  Out of curiosity I dropped the chunk in evaporust, and it took a week of soaking for it to clean.  Also, check out my oil pump!!   That is after it kinda got sprayed with PB.

I finished pulling my valves and LOOKY WHAT I FOUND...  Looks like the PO tried to do some porting on the intake side only...  I guess it'll be fine, I had considering doing a little myself, but I'll leave it.

Cylinder #1:


Cylinder #2:


Cylinder #3:


Cylinder #4:


A rather nasty oil pump:


For anybody interested in whatever pics I have from this build, I have an album here:  http://s230.photobucket.com/albums/ee291/Lavis325CL/1973%20Honda%20CB500%20-%20CURRENT%20PROJECT/

[fastbroshi]

Minnesota, anywhere in the UK...'nuff said.  



Got a bit of wear here?  Maybe I missed it, but was the bike running before you got your idle hands on it?    If it was a non-oring chain it should be alright.  Mistake some owners make is putting an o ring chain on there and it wears the cases because it's too wide.   Usually eats into the seal there = split the cases.  Yours looks like it might be fine.  I wouldn't eat off of it just yet though.

[Lavis500]

Before I bought it, this bike had been sitting for 7 years since it had last ran.  When it did, it was bought by a young man from a used car salesman who owed him a favor.  He bought it not running and as far as I was made aware (I got the story from his father, not him) he tinkered with it for a few hours, got it barely running and then rode it like that all summer.  Then he joined the army and it sat for those 7 years.  Any history before that is unknown.  I didn't care though...  I got a title!! 

Actually, I made a note on this wear in my build thread.  The chain seems original (or at least NOT an o-ring chain and REALLY rusty), but the SPROCKET was changed out...  it only had 15 teeth.  I tried shimming the sprocket away from the case, but to no avail.  I actually WAS blaming the chain until I got bored and counted the teeth on the sprocket.    Thankfully the wear is nothing more than a little marring.  There isn't even a noticeable difference in the surfaces.  You're right about not eating off it, though... I've had the cover soaking in a purple power/water solution for a week!  Not that it needed to be in there that long, there were just other more interesting things for me to do.  I'm actually going to attempt washing it tomorrow.

I've tried looking for chains.  Where does one procure a non o-ring chain to avoid hassle?

Anyways, goin to bed for tonight.  Broshi, I make frequent trips to dallas as my family loves there, and I happen to live not too far away.  After I get this thing done in a couple months how would you feel about riding with me?  Maybe show me what the 500/550 is capable of?  

[dave500]

get yourself an impact screw driver aswell if your budget goes that far,the type you hit with a hammer,this is for the stubborn phillips/jis headed screws ,replace them with stainless allen head types.

[fastbroshi]

No prob dude, let me know.  Hopefully I'll have made some progress on my other 550 by then.

[Lavis500]

Went back to autozone and found one of the parts jockeys that knew what he was talking about (he'd proven this to me a few weeks before).  I asked for plastigage and he grabbed it.  He said they sell out of it pretty fast.  I have the red and green strips.  I won't need the yellow or blue, will I ?

[thehammer]

did you remember to zero out your vernier caliper? I forget to do that alla time.