This is on a 1980 CB750 DOHC...
I had an upper timing chain break, resulting in 2 bent valves and worse, 2
broken valve guides.
Rather than trying to swap valve guides, I picked up a cylinder head from
the same year model really cheap. It has the cam bearing caps, but not the
cams or the shim buckets.
So my question...
How bad is it to use the old cam and shim buckets in a different head?
Must this be machined to match? Should I plastigauge it?

Paul Barrett <(E-Mail Removed)> wrote:

> How bad is it to use the old cam and shim buckets in a different head?

You'll be fine. It's the cam bearings that are matched to the head.
Otherwise, if you think about it, you'd never be able to replace a
camshaft without changing the head as well, which would have put
Yoshimura and others out of business decades ago.


--
BMW K1100LT Ducati 750SS Yamaha XTZ660 Tenere Honda CB400F CB250N SH50
chateau dot murray at idnet dot com
"What you're proposing to do will involve a lot of time
and hassle for no tangible benefit."

On Nov 30, 5:33�pm, "Paul Barrett" <s...@barrettmanor.com> wrote:

> How bad is it to use the old cam and shim buckets in a different head?
> Must this be machined to match? �Should I plastigauge it?

Plastiguage is a crushable plastic fiber which is typically used to
approximate how much clearance there is between the crankshaft and the
main and rod bearings.

Plastiguage is an inexpensive substitute for precision micrometers.
The home mechanic can determine whether he needs over-sized bearing
inserts or if the crankshaft is badly worn without buying the expen
$ive
micrometers.

As I recall, the original Kawasaki Z-1 engine had removable cam
bearing inserts.

However, modern Japanese overhead cam engines don't have bearing
inserts
in the head, they run the camshaft directly in the aluminum head and
if the
head is damaged you would have to replace it, unless you can find a
really good motorcycle machine shop that knows how to line bore the
bearing caps and head.

In any case, you need the factory shop manual to find out what the
dimensions of the cam bearings and lobes should be and then you need
to use a bit of judgement if the parts are worn a thousandth of an
inch or some more than the manual limit.

On 1 Dec, 13:08, "." <yefelnag...@yahoo.com> wrote:
> On Nov 30, 5:33 pm, "Paul Barrett" <s...@barrettmanor.com> wrote:
>
<snip>


In other words, you have not answered the question. So you don't
actually know what you are talking about. On a great many Jap bikes,
the cam caps are matched to the head, like I said.

Oh, and some modern Japanese bikes use roller bearings in their heads
as well.

If the head and cam bearing caps are in fine condition, and ditto the
replacement cams, then all the OP needs to do is to bolt in the
replacement cams and ride away.

If any or all of the cam caps and head bearings surfaces are buggered,
then obviously he'd need to do a whole load of work, but the fact that
he's trying simply to avoid replacing two valve guides (not in itself
a tough job, but one for a specialist) would suggest that there's
nothing wrong with the used head he's bought. And if the camshafts he
wants to put in it were buggered also, I don't think he'd be shoving
them back in his bike.

Barrett - like I said, just put the cams into the used head, and bolt
that onto the block.

On Dec 1, 7:35�am, "TOG@Toil" <totallydeadmail...@yahoo.co.uk> wrote:

> Oh, and some modern Japanese bikes use roller bearings in their heads
> as well.

First generation Honda pile-of-craps had roller bearings on the ends
of the cams.

But name just *one* Japanese design from the middle 1970's and up that
has *roller bearings* in the head.

If you can be bothered to support your incessant *quibbling*, that is.

On 1 Dec, 16:24, "." <yefelnag...@yahoo.com> wrote:
> On Dec 1, 7:35 am, "TOG@Toil" <totallydeadmail...@yahoo.co.uk> wrote:
>
> > Oh, and some modern Japanese bikes use roller bearings in their heads
> > as well.
>
> First generation Honda pile-of-craps had roller bearings on the ends
> of the cams.
>
> But name just *one* Japanese design from the middle 1970's and up that
> has *roller bearings* in the head.
>
> If you can be bothered to support your incessant *quibbling*, that is.

Kawasaki ZX7R. Kawasaki ZX9R. Both do, at the camchain drive end.
Possibly others as well, and I cba to check right now, but those two
do for certain, and I know, because I've worked on 'em. Which,
evidently, is more than you have.

Plain bearings elsewhere, but nonetheless roller bearings they use.

Are we feeling stupid now? :-)

TOG@Toil <(E-Mail Removed)> writes
>
[]
>
>Barrett - like I said, just put the cams into the used head, and bolt
>that onto the block.

That sounds about right - when I blew up my first CB900 (long stroke
version of the same engine) we used the inlet camshaft & buckets from
one engine & exhaust cam from another.

It went fine until it suffered an ignition failure and I replaced it
with a cheap VFR...
--
Bob Scott

On 1 Dec, 16:24, "." <yefelnag...@yahoo.com> wrote:
> On Dec 1, 7:35 am, "TOG@Toil" <totallydeadmail...@yahoo.co.uk> wrote:
>
> > Oh, and some modern Japanese bikes use roller bearings in their heads
> > as well.
>
> First generation Honda pile-of-craps had roller bearings on the ends
> of the cams.
>
> But name just *one* Japanese design from the middle 1970's and up that
> has *roller bearings* in the head.
>
> If you can be bothered to support your incessant *quibbling*, that is.

Oh, and as you're so fond of posting fiches, here you go:

http://tinyurl.com/6dvryp

You can clearly see the ball races at the end, by the cam sprockets.

On Dec 1, 8:54�am, "Giant Turd in the Punchbowl"
<totallydeadmail...@yahoo.co.uk> wrote:

> http://tinyurl.com/6dvryp
>
> You can clearly see the ball races at the end, by the cam sprockets.

Whatever got you so worked up that you actually looked something up to
win
a useless argument?

What does this have to do with a 1980 CB750, anyway?

Horst Weltschmerz <(E-Mail Removed)> wrote:

> > http://tinyurl.com/6dvryp
> >
> > You can clearly see the ball races at the end, by the cam sprockets.
>
> Whatever got you so worked up that you actually looked something up to
> win
> a useless argument?

Bwaaahahahahaha! Look at the timing of the postings. I'd already told
you the truth, before I even bothered to look this up.

In other words, I didn't look it up because I needed to "win an
argument". I already knew it. I gave you the link for your benefit,
because I'm a nice chap.

And why did I state it? Because you, *once again*, paraded your complete
lack of knowledge in a technical ng and your ignorance warranted
correction.


> What does this have to do with a 1980 CB750, anyway?

Bwaaaahahahahaha! You utter, utter *loser*. You give the OP a load of
irrelevant waffle, it's corrected for what it is, you start jumping up
and down and screaming, demand proof of what I said, and it's
provided...

....and then you ask a question like this?

LOSER!



--
BMW K1100LT Ducati 750SS Yamaha XTZ660 Tenere Honda CB400F CB250N SH50
chateau dot murray at idnet dot com
"What you're proposing to do will involve a lot of time
and hassle for no tangible benefit."