Topic: Camshaft and camshaft bearing CB 750 K1

[Mushu]

I am starting a top end refurbishment on my K1.

When measuring camshaft axle and camshaft bearing I have a question for you.

I use Honda workshop manual and Hondaman book.

Workshop manual defines inner diameter (21.789-21.810 mm) and outer diameter 21.939-21.960 mm) for camshaft. Inner diameter are 0.15 mm lower than outer diameters.

I found only one value for cam tower bearing diameter (22.02-22.041 mm).

Is there a value that I have been missing for inner camshaft bearings?

If not, the clearance for inner bearings/camshaft axles is greater than for outer. Am I right?

Sorry for mm units. My CB is the french one :-)

[Mushu]

Hi Guys,
Is there somebody which helping me providing the answer?

Thanks in advance.

[kmb69]

You are correct. That's how Honda specs them.

The cam holders are the same and are interchangeable. There is no left and right or inner and outer.

[Mushu]

Many thanks kmb69.

Do you know the reason why the clearance is so wide for inner camshaft bearings?

I was worried about this clearance and oil pressure on camshaft towers.

Anyway, I will sleep on my two hears now  .

[kmb69]

Many thanks kmb69.

Do you know the reason why the clearance is so wide for inner camshaft bearings?

I was worried about this clearance and oil pressure on camshaft towers.

Anyway, I will sleep on my two hears now  .

Sorry, I do not know why Honda did it that way.

[PeWe]

Cam bearings have been discussed in a thread before. I think Hondaman contributed with important information. Only way to find it is to search with Google and proper search expression.

For me it is enough to check the cam holder bearings visually. It is visible if there is wear. I have holders that got wear due to cam holder did not sit flush on head. Thread inserts had creaped up a little. The upper cap never get wear unless no oil at all. Recently a thread that wear sideways could cause lowered lift on either side if I remeber correctly.

All information is to be found in these forums, just find the correct search expression

[Mushu]

Thanks Pewe,

All the measurements seems Ok for bearing and camshaft.
I take care of it because 30000 km and 14 years ago I did not put the small O rings at the end of the Oil passage within cam towers.
Concequently, after hearing more and more noise like click-click in the top end area, I decide to open the engine.
I am changing rocker's shafts, rockers an camshaft.
I also replace pistons by 61.5 mm from cruzinimage

I will search again for the camshaft info.

I will open a project post to document my rebuild of the top end.

[Mushu]

I found a post on this cam shaft subject with answers from Hondaman.

http://forums.sohc4.net/index.php?topic=43357.0

Many thanks and I whish you a good year for 2017.

[PeWe]

It has been more about this but I cannot find it. My conclusion is that the most important thing is clearance and not too heavy scuff marks on the cam holders bearing area and cam itself. It seems it needs to be a big catastrophe to not be possible to use the cam holder.
Like running out of oil due to clogged oil orifices that get its oil via oil channel from filter and before that oil pump. No sealer around cases will land there unless it is applied a lot around the channel between cases where the 183 O-ring seal.

One thing I had worried about is a bent head, tighten it and it will get a bent surface against cam holders that might squeeze cam.
I checked surfaces on both sides, flat and fine.
Cam should rotate with ease when mounted in cam holders that can be checked by tighten the holders before mounting the rockers.

There are more good information when working with cam and holders. Aware of overtighten the cam bolts and the cam studs that might ruin the thread in head. No 2 stud has not much mtrl around in head. I have repaired mine 3 times. Hopefully last time now.
7 ft lbs/10 Nm is enough for the M6 bolts and nuts.

Here more to read: http://forums.sohc4.net/index.php/topic,55599.0.html
http://forums.sohc4.net/index.php/topic,7401.0.html