3. Engine Mechanical
Hi to all and welcome to this new and exciting web site which is specifically devoted to the sandcast CB750 herein to be referred to as VIN 1/7414.
Firstly, recognition needs to be given to Steve Swan for his inspiration and drive to get this site up and running. It�s been a long time coming and well done Steve. You know, a fellow sent me an email recently and said that this was a great idea as he was finding it difficult to get information about his restoration project. Well if you are in need of info, then this will be the site to visit
Anyway, I thought it would be great if a technical contribution was made to get the ball rolling as it were, and I will get discussion going by talking on the various castings of the K0 series cylinder head. The SOHC CB750 was a great leap forward in motorcycle design and manufacturing and broke the stranglehold that British motorcycles had on worldwide sales of large capacity motorcycles. Honda was no different to other manufacturers with the early production of the CB750 in that casting of major engine components was undertaken using sand as the mould medium. Otherwise the similarity ended there ��� read on
There were many details and design variations of the CB750 and CB750K series over its production cycle and there have been numerous publications produced covering these design and manufacturing changes. I won�t bore anyone with a rehash of what has already been written; however little has been written on any specific model, and particularly the various detail and design changes to VIN 1/7414 and the first CB750 (known collectively as the K0) model generally.
As indicated earlier, I want to limit my discussion on production changes made to VIN 1/7414 and later K0 series cylinder heads, as there are at least 3 variations to the casting that I am aware of. And before ya�all come back and say there are more or less, remember this is the start to all discussion and we all want feedback. This web site is here to share knowledge and stimulate discussion. Any additional information will not only be a benefit, it is sought
I have included pictures of two specific head castings. The bottom (and cleaner) head casting is from my own VIN 1/7414, which I refer to as the earlier casting and the top shot is of a later casting. Externally, there is no way of identifying the earlier from the later casting but once the cam cover is off, it is a very easy process to identify. Main differences are:
1. Later head has no casting depression between rear head bolts
2. Later head oil return hole more pronounced and better designed to drain oil
3. Later head has tapered valve guide, and no provision for oil guide seal
4. Later head has larger scallops on both sides
There are other minor variations such as the #2 cast into the recess at the cam chain space, but I cannot state if this is common to all later castings. It should also be noted all early and later heads show some casting and design variations, which are minor. This is not uncommon, as casting boxes were in themselves not uniform. Thus, only significant design changes have been identified. Now, this is where it gets a bit gray. I believe this later casting commenced in the area of VIN 149xxx and ran until VIN 22xxx. After this VIN, provision was made for an additional bolt in the casting to answer an oil seepage problem, which was characterisitc of these early engines. I also understand about this time, all heads were manufactured using a die casting process in lieu of the sand casting process used up unitl this time. Certainly, there is no mistaking the sandcast heads from die cast heads. As for the later K0 heads, if you have a damaged VIN 1/7414 head, theere is little issue with using a later K0 head. Change the exhaust valve guide to the oil seal type and Uncle Billy Bob is really your Uncle Billy Bob.
Any one shed more light on this subject, either email me or Steve through the "Contacts" page and I will be happy to update this tech topic. See ya'll, ya'hear........................KP
Oil Line Types
Early Type - Smooth Fabric, Not Webbed, Ferrule Not Crimped
 
Early Middle Type Oil Line - Webbed Fabric, still features smooth ferrule
Late Type Oil Webbed Fabric Line - Crimped Ferrules
* Oil Filter Case Sandcast and changing - Manfred Doering
Picture 1 - 4 shows a ORIGINAL Sandcast Oil Filter Case
from my early Sandcast Bike Engine # 1000699
Picture 5 and 6 shows a Very Good REPRODUCTION OIL Case
Picture 9 and 10 shows the Oil filter case Changing at engine
1004148 to honda part no. 15411-300-010
No # 2 stamped on the Top , Correct Oil Filter
Case for Sandcast Bikes Starting 10004148
Picture 7 and 8 shows the replacement Oil filter Case
with the # 2 stamped on the Top
Back to Table of Contents
|
