Honda CB750 Sandcast

General Category => General Discussion => Topic started by: markb on February 27, 2011, 04:18:32 pm

Title: Differences in left rear transmission (drive sprocket) covers
Post by: markb on February 27, 2011, 04:18:32 pm
While looking at my left rear transmission cover I noticed a difference.  E100's cover was missing so I am going to borrow the one from E1789 for now.  I noticed it was different from E5491.  I see in the parts books that it was the same from 1-26143.  Here's the one from E1789. 
(http://cb750sandcastonly.com/coppermine/albums/userpics/10002/DSC05791.JPG)

This one's like the one that's on E5491.  It's got a post where a rubber chain guide goes.  Were all sandcast covers the same and up to 26143 diecasts?  Does this mean that the one that's on E5491 is incorrect? 
(http://cb750sandcastonly.com/coppermine/albums/userpics/10002/DSC05792.JPG)
Title: Re: Differences in left rear transmission (drive sprocket) covers
Post by: markb on February 27, 2011, 05:35:37 pm
I think I answered part of my question.  My 12xxx diecast has a cover like the one on E5491.  I know that was the original cover because I bought the bike in '75 from the original owner and he never touched it.  So there definately was a change before 26143.  Did it happen in the sandcasts?
Title: Re: Differences in left rear transmission (drive sprocket) covers
Post by: Wayne on February 27, 2011, 05:48:58 pm
For what it's worth Mark, 576/748 has a cover as shown in your first image.
Title: Re: Differences in left rear transmission (drive sprocket) covers
Post by: Riccardo on February 27, 2011, 06:12:32 pm
Also my 737 has the cover as the first photo.
Title: Re: Differences in left rear transmission (drive sprocket) covers
Post by: kp on February 28, 2011, 03:50:09 am
Fellas, From what I've seen to date there are 3 sprocket covers for early bikes. I will have to take a photo of #3 next week but for now here are 2 covers we know about. As is my usual practice I recognise the source the first time I use the picture
Photographs by Steve Venzetto and Chris Rushton and I bet both have forgotten they took them.
Remember, I have a 3rd photo but will add it later.

Title: Re: Differences in left rear transmission (drive sprocket) covers
Post by: vnz00 on February 28, 2011, 04:54:16 am
KP, I never forget a photo ;)
Yes there were 2 early versions - one was a die cast version, the other looked like a sandcast version.  The diecast version is the one that came out on Production bikes up to 26000 as far as I remember.  You can see they look more solid.  The diecast early version has '232' cast onto it.  The other appears to have been produced as spares only.   I have seen one in the flesh, and one on the CMSNL website.  You can see very clearly on the inside, the finish is rough.

I think the later ones had a rubber sleeve inside, and possibly the inner sprocket guard.  If it had the inner sprocket guard, when seen mounted on the bike, the cover has a visible recess to accept the inner sprocket guard.
Title: Re: Differences in left rear transmission (drive sprocket) covers
Post by: kmb69 on February 28, 2011, 06:14:16 pm
I am 99.9% sure the version with the rubber covered guide was part of the retrofit that included the chain guide that was mounted on the cases in front of the sprocket and the riveted master link chain. I worked for Honda at the time but I cannot find the documentation for this change. Replaced a bunch of them back in the day. On most of Honda's official recalls they didn't want the old parts back and the original parts were thrown in the trash.

Keith
Title: Re: Differences in left rear transmission (drive sprocket) covers
Post by: kp on March 05, 2011, 04:22:27 am
Fellas, Here is the 3rd K0 cover I promised to get a picture of KP
Title: Re: Differences in left rear transmission (drive sprocket) covers
Post by: Steve Swan on March 05, 2011, 09:46:47 am
It's really cool to listen to the findings we share. 

Today we know so much more than we knew in 2004 when the website started up.

We'll contnue to learn more as we share more.

This is great stuff ! 

Thanks to all who are sharing !