Topic: 1972 CB450 "Supersport" NOW SHE REALLY LIVES!!!!!

[dagersh]

Ugh the MF'ing Cam Chain broke at the lower end.  I pulled equal lengths of chain from both exhaust and intake sides, so I am assuming it was at the bottom.






So, 2 questions;

1.  Honda CAM chains still available?

2.  What are the odds that I fired the Valvetrain?

Now I am really sick to my stomache...

[Killer Canary]

The first time my 350 died, the cam chain was in pieces. What happened was that the tensioner idler was worn enough to wobble and threw the chain. Could this be what happened to yours? I don't see parts availability being a problem for you. FWIW, if mine was a 450, I'd be having it rebuilt a third time.

[dagersh]

Thanks Canary,

I will get this thing running right.  I will look at my tensioner and see if there is any side to side play.  If so, I have a spare.

Gersh

[maduncle]

Hey Gersh - at least you found the problem easily enough.

Let me know if you find a Honda OEM chain, then I will know wher to get mine.

I would be trying CMSNL first up to see if they still have OEM stock.

[Doctorlumen]

Holy crap, Gersh!

If the bike didn't actually catch and idle, I think the valvetrain will be okay. But the bottom end will need to be inspected. Hang in there man....She'll be up and running in no time!

If its any small consolation, my machinist busted a valve guide on installation friday, so I had to source him another...from the UK. Guess it wasn't a good weekend to be a 450.

[dagersh]

Doc,

You are right, not a good weekend at all.  I hope you are also right about the valvetrain...

Good luck with yours!

[dagersh]

Ok - I am back!

The news is not so disastrous after all – I think, anyway.   I pulled the head and cylinder.  The pistons and valves are all unmarked, so there was no contact.  I am going to send the head and everything else out to a machine shop to make sure all the valve-train is playing nicely with each other.  If that is OK  - I will send the Cams and Tappets out to Ken at CycleX for his coating to reduce friction.  I spoke with him at length – great guy, BTW – and with the overly optimistic oiling system of the CB450’s it will help protect things a bit better.  Mind you, this is in no way a substitute for a proper working oiling system, but just a help along.
Here are the valves:



Speaking of which - it looks like the exhaust side was not getting any oil flow.  The intake side had a good amount of oil in the side-cover and in the Cam, but it looks like my sloppy attempt with sealant blocked the exhaust side.  Also, I have buggered the THR Copper Head Gasket.  Any idea if there would be a problem with using an OEM?  The openings are just fine for the oversized pistons, but I am concerned about the thickness.
There are some weird things going on, though.  When I drained the oil, it was full of tiny aluminum shavings – which at first made me believe the head was shot.  But no, the cam chain was rubbing on the Exhaust Side of the cylinder Cam Chain Tunnel…




Weird….

What do you guys think?  What caused the Chain to do this?  There is no way I had the chain routed incorrectly, there is no way it would fit.

Looking forward to your responses!

Gersh

[lucky]

I was a dealership mechanic from the time the first CB450 arrived.
That mark where the cam chain was rubbing on the case is caused by owners not
adjusting the slack out of the cam chain. Many owners had never done it, and when it started to make noise they brought it to the dealership and just a cam chain tension adjustment took care of the problem. They were amazed at how quiet the engine was.

The cam chain adjustment MUST be done with the crankshaft in the correct position as described in the workshop manual - VERY IMPORTANT.

Although the bike can have very few miles on it, the rubber rollers and cam chain guides have been sitting for more than 30 years!

Some CB750 owners just run the bikes when they get them because it has low miles and soon find little bits of rubber in the sump screen.

IF a cam chain gets loose from out adjustment tensioners then the cam chain gets jerked on every revolution. That is what causes it to break. Uneven tension.

[dagersh]

Lucky,

Thanks!  That makes alot of sense.  Remember, though, the bike never actually started, it was revoloving on the electric start when the chain broke.  I did rebuild the tensioner, and it was sliding nicely upon its install.

Would there be enough slap to break the chain under just the electric start?

Gersh

[Cqyqte]

Ok - I am back!

The news is not so disastrous after all – I think, anyway.   I pulled the head and cylinder.  The pistons and valves are all unmarked, so there was no contact.  I am going to send the head and everything else out to a machine shop to make sure all the valve-train is playing nicely with each other.  If that is OK  - I will send the Cams and Tappets out to Ken at CycleX for his coating to reduce friction.  I spoke with him at length – great guy, BTW – and with the overly optimistic oiling system of the CB450’s it will help protect things a bit better.  Mind you, this is in no way a substitute for a proper working oiling system, but just a help along.
Here are the valves:



Speaking of which - it looks like the exhaust side was not getting any oil flow.  The intake side had a good amount of oil in the side-cover and in the Cam, but it looks like my sloppy attempt with sealant blocked the exhaust side.  Also, I have buggered the THR Copper Head Gasket.  Any idea if there would be a problem with using an OEM?  The openings are just fine for the oversized pistons, but I am concerned about the thickness.
There are some weird things going on, though.  When I drained the oil, it was full of tiny aluminum shavings – which at first made me believe the head was shot.  But no, the cam chain was rubbing on the Exhaust Side of the cylinder Cam Chain Tunnel…




Weird….

What do you guys think?  What caused the Chain to do this?  There is no way I had the chain routed incorrectly, there is no way it would fit.

Looking forward to your responses!

Gersh

I am betting that you didn't get all of the slack out of the exhaust side of the cam chain when you rejoined it.  If so no matter how much you adjust the tensioner the chain will flail and drag on the case.  It's just my guess at this point, but I am relatively certain.

[fastbroshi]

  I seem to remember you had a problem fitting the valves' tensioner spring on one of the cylinders.  Is it possible this is related?  Whenever I'm working on something and I have to "persuade" things forcefully it's usually  a sign I'm doing it wrong or something is amiss.  Also, the part of the cam chain tunnel you showed, are those witness marks fresh?  Because it looks clean, as if there's no oil it.  The gold cam chain doesn't look like a stocker.  Did you replace this as well?  If so, is it possible it was a link or two too short?

  I don't know how you can stand all this.  The bike looks beautiful but is not operational because of the motor.  Before starting a restoration, I've seen the majority of people start with the motor first and get that dialed in, then start on making it pretty.  It's a lot easier and faster working on the motor when you don't have to worry about chipping and scratching things.  Just food for thought.  Good luck with it from here on out. 

[grcamna2]

I did a nice overbore top end job on a CB450K7 and it was a Real BEAR to keep both ends of the cam chain taut while engaging ALL the rollers w/ their little twists & turns..and then being certain the valve timing was correct once I released the cam chain tensioner bolt ! every time I released the bolt..it would jump valve timing one notch.I adjusted my strategy a bit and used 2 heavy lengths of safety wire to "try" to keep even pressure on both ends of the cam chain so it wouldn't bunch up down below..kind of hooking each piece of wire w/ tension at the same time w/ a push/pull kind of action(it took me a few hours)while I attempted to join the master link on the O.E. cam chain.
 It was a REAL pain to do by myself; if I had a helper to keep tension on the rotor bolt while I did this procedure...that would have been a Nice thing.If I only had 3 hands  !

[Doctorlumen]

Unless it tore, that THR copper head gasket should be able to be anealed. Maybe shoot them an email and ask....

Aluminum in the oil after a build is to be expected...in the form of a sparkly haze in the oil. Actual "chunks" are not okay, and I've understood "chunk" to be anything the size of or bigger than a grain of salt. But I'm sure there are all sorts of opinions. Are you sure those chain tracks weren't there before? If you are sure, then there is your aluminum shavings.

I'm casting my vote in the "not enough tension" camp. The tensioner assembly on these bikes is extensive and complicated. I know I'm not looking forward to setting mine up!

[thrutheframe]

  Pardon the minor thread jack but doctorlumen, are you a lighting guy?

[maduncle]

Bump!

So 'gersh - how is the 450 fix up going?

I am re-reading your entire thread for tips on engine assembly - such good stuff there.

[dagersh]

Hey Unc -

She's on the stand, timed and tensioned, just waiting to be put back into the frame, and hopefully, started.

Can't wait to see your bike up and running!

Gersh

[srbakker]

Somehow I've missed this one until now - I love the color combo and the seat!  Real sweet work there.

[Znabb]

Hi Gersh,
I've been looking through your project log trying to find info if you used bored out stock sleeves with the 74 mm THR pistons?

As Doctorlumen mentiong the copper head gasket can be annealed and used again. You can see in this video (at 1:20) from THR how they anneal it.
youtu.be/bxXFNLlcZNM

Bummer that the pictures is gone from this log. I would love to read it again with pics.

[dagersh]

Alright….  Almost a year out from an update.
Happily, I have only great news.  She runs - pulls like a freight train, actually – and is RIGHT!!!

After the cam chain exploded, I was able to diagnose no oil flow to the heads.  In fact, I pulled out a bunch of silicone sealant from an improper installation of the Copper Head Gasket.  I am not sure what went wrong, but it did.
I installed a new head gasket on top of Cycle X’s treatment of the tappets.
In short, once that was accomplished, I got married and had to put everything on hold for while….

I got back to the project and the stock Keihins were not cutting it.  I had to install a pair of VM32’s from Mikuni.  These carbs are GODSENDS for a Honda twin with massive intake/exhaust changes.  Try as I might, I  could not the Keihins to deal with the massive intake of air between the 500cc over bore, velocity stacks and BCR Peashooter Exhaust.  The VM32’s from Power barn, pretty much out of the box made the bike idle nicely, although I have fine tuning to do.

I was able to run the bike up and down the block before the snow fell, and man…..  this thing pulls!  I can’t wait to run this thing for more than 10 min.  I will continue to dial in the air/fuel mix, as I am running a little rich at the moment.

Since winter has arrived, I have time before I can run her.  Thanks to everyone for their help and support!  I will be posting pics and videos soon.
Gersh

[cheftuskey121]

any updated pictures? can never have enough

[dagersh]

Soon, I promise.

[dagersh]

Here she is running without any tuning.... 

CB 450 Project

[sethdhawkins]

Any updates to this build? Did you bore the stock sleeves of your engine out to 74mm with the big bore? I'd love to see some more pics, as everything from page 7 doesn't work for me!

[dagersh]

Seth,

I am waiting for the snow and sand to clear so I can finish tuning her up.  I was able to take her for a nice little run before the snow fell, and it runs great.

I did bore out the the stock engine for the THR kit.

Facebook switched all the links to the pics on the build, I have been going back sowly to put it back together again.

Here are links to the albums on my facebook that deal with the build:

https://www.facebook.com/#!/michael.gershon.3/media_set?set=a.15281373442.26591.595383442&type=3


https://www.facebook.com/#!/michael.gershon.3/media_set?set=a.264657943442.139474.595383442&type=3


https://www.facebook.com/#!/michael.gershon.3/media_set?set=a.10150220605688443.309753.595383442&type=3


https://www.facebook.com/#!/michael.gershon.3/media_set?set=a.10150619453113443.378064.595383442&type=3

Let me know if you need anything else.

Gersh

[sethdhawkins]

You da man! I'm torn between the THR pistons, and Charlie's Place 1.5 over. Longevity, or power. Hmmmm...