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Author Topic: 78 CB750 front sprocket spacing?  (Read 6699 times)

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Offline blackhog02

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78 CB750 front sprocket spacing?
« on: July 19, 2005, 09:46:19 PM »
Just picked up a 78CB750 and have a question about the front sprocket.  It looks like the PO had put a 16 tooth sprocket on the front. OEM looks to be 15 according to service honda site.  The sprocket uses the standard plate with two bolts to hold it on but the 78 CB750 uses the one bolt with a big flat washer and does not have the grove in the shaft to turn the plate and lock the sproket onto the shaft.  It looks like from a previous post that the OEM front sprocket has a raised face to take up the space. 

http://www.sohc4.us/forums/index.php?topic=2313.0

The washer and bolt tighten up against the drive shaft and leave a lot of free space between the washer and the sprocket so the sprocket has a lot (seems very excessive) of movement in and out on the final drive shaft.  Is this normal or do I need to find a way to shim up this sprocket? I was thinking of finding a plate and using it as a spacer.    The PO used some silicon between the washer and the sprocket.  Or do I need to find an OEM sprocket? 
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Offline Terry in Australia

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Re: 78 CB750 front sprocket spacing?
« Reply #1 on: July 19, 2005, 11:09:59 PM »
That's a "Bodgie" set-up mate, some kinda home made 630-530 conversion? Yours should have the bolt and flat washer securing it to the output shaft. If you want a factory workshop manual on CD let me know, I can burn you off a copy for your particular bike.

I traded one with Dan in San Jose for  copy of Hustler last week, but "Evil" Don Ballasch in Ohio reckons "Juggs" is more informative, with better, er, articles, ha ha! Cheers, "creepy" Terry. :o   
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I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

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Offline blackhog02

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Re: 78 CB750 front sprocket spacing?
« Reply #2 on: July 20, 2005, 06:24:13 AM »
Terry, A shop manual on CD would be way cool.  I looked at the chain and it is a 530 so it looks like you are right a bad 630 to 530 conversion.  Anyone know if I can use an old plate to space the sprocket or do I need to convert everything back?

Bart 
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Offline Terry in Australia

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Re: 78 CB750 front sprocket spacing?
« Reply #3 on: July 20, 2005, 02:25:13 PM »
G'Day Bart, you should be able to buy a "proper" 530 conversion kit front sprocket so you can keep your chain and rear sprocket, a modern 530 chain is just as strong or stronger then the OEM item, and lighter. Post another question: "Where do I get a 630 to 530 chain conversion kit" and the answers will flow.

If you want a copy of the CD, PM me your shipping address, and I'll get it out to you. Another sohc-er has offered me a copy of "Juggs" for a copy of the CD, so you'll have to come up with another brand of er, tech manual in exchange, ha ha! Cheers, Terry. ;D
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I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline dpen

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Re: 78 CB750 front sprocket spacing?
« Reply #4 on: July 22, 2005, 06:53:13 AM »
My K7 (June '78 build) has the same setup. The play in the sprocket is normal. This setup is used on a lot of trailbikes. The slight sideways movement compensates for minor misalignment caused by such things as a not-aligned rear wheel.
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bearcatamo

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Re: 78 CB750 front sprocket spacing?
« Reply #5 on: July 29, 2005, 01:58:09 PM »
I just changed out my chain and sprockets for the first time since I bought it. When I took off the front sprocket cover I discovered another "rigged" job. The A-hole before me evidently lost the locking plate and bolts for the front sprocket and instead put a HOSE CLAMP ON COUNTERSHAFT!!!!!! A feeling of dread came over me as I thought of what could have happened as I blasted down I-95 approaching 100mph!

Barry in FL
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Offline Einyodeler

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Re: 78 CB750 front sprocket spacing?
« Reply #6 on: July 29, 2005, 02:21:31 PM »
Quote from: bearcatamo on July 29, 2005, 01:58:09 PM
I just changed out my chain and sprockets for the first time since I bought it. When I took off the front sprocket cover I discovered another "rigged" job. The A-hole before me evidently lost the locking plate and bolts for the front sprocket and instead put a HOSE CLAMP ON COUNTERSHAFT!!!!!! A feeling of dread came over me as I thought of what could have happened as I blasted down I-95 approaching 100mph!

Barry in FL


 :o :o :o :o :o
Man, your guardian angels were working overtime! I`d double check every nut & bolt on it after finding that.
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Buffo

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Re: 78 CB750 front sprocket spacing?
« Reply #7 on: July 29, 2005, 04:46:14 PM »
I had the same qustion about my 1978 CB750K8.  and was told the same thing. the side to side is normal. I just went to the hardware store and bought a big ss washer.

Don
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Offline Terry in Australia

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Re: 78 CB750 front sprocket spacing?
« Reply #8 on: July 30, 2005, 03:47:44 AM »
We need to keep in mind here, that Blacky's running a narrower 530 sprocket that was a "bodgie" installation by a PO, and not the factory setup with a small amount of built in side play, but about 1/8".

Blacky, these guys all mean well, but there is no way that 1/8" is normal, safe, or even ok. For the price of a proper front sprocket, you could well save yourself a lot of trouble, and maybe your own life. Cheers, Terry. 8)
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I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline Bob Wessner

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Re: 78 CB750 front sprocket spacing?
« Reply #9 on: July 30, 2005, 04:03:52 AM »
I agree with Terry. The amount of "play" folks refer to is quite negligable in a proper set-up. Just enough to deal with slight side-to-side chain movement.
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Offline Quail "Owner of the comfortable k8"

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Re: 78 CB750 front sprocket spacing?
« Reply #10 on: July 30, 2005, 06:49:15 AM »
The cover plate on the 77/78 is different than the early years also.  It has a post in the casting that almost touches the head of the bolt that goes in the end of the shaft through the sprocket.  I drilled and tapped my new sprocket and used the locking tab set up the older bikes used.  I did not like the way it moved in all four directions when it was loose on the shaft.  Seemed like a lot of wear that could be avoided.
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Offline blackhog02

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Re: 78 CB750 front sprocket spacing?
« Reply #11 on: July 30, 2005, 04:24:10 PM »
I picked up one of the plates that  holds the sprocket on the shaft on the earlier year 750s and that took up the space then I put some lock tite on the bold and bolted it back up. It now fits snug.  Now I can get it running and tuned up.  I am planning to replace the sprocket when I move it over to the ridgid frame.

 I patched the hole in the case with some devcon and it seems to be holding.  Now that it is not the Exxon valdieze what grade oil should I put in it to fill it back up? Its a 78 CB750

Thanks Bart 
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Offline dpen

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Re: 78 CB750 front sprocket spacing?
« Reply #12 on: July 31, 2005, 05:00:34 AM »
Quote from: Terry in Australia on July 30, 2005, 03:47:44 AM
We need to keep in mind here, that Blacky's running a narrower 530 sprocket that was a "bodgie" installation by a PO, and not the factory setup with a small amount of built in side play, but about 1/8".

Blacky, these guys all mean well, but there is no way that 1/8" is normal, safe, or even ok. For the price of a proper front sprocket, you could well save yourself a lot of trouble, and maybe your own life. Cheers, Terry. 8)
Dunno Terry.
I was really worried when I got my K7, having had no experience with these bikes before but I contacted the SOHC club of Victoria.
The bloke there set my mind at rest & I've done about 20,000 klicks with around 1/8 inch play & chain & sprockets are still mickey mouse.
Mind you, I wait until I'm going before I nail it.
By the way, I also checked up when I bought the sprockets (from an old bloke who has a dealership in Sydney - with his dad!!! - Beaconsfield Honda) & he also assured me that it was ok.
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Offline Terry in Australia

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Re: 78 CB750 front sprocket spacing?
« Reply #13 on: July 31, 2005, 05:16:08 AM »
Fair enough Dave, "You can lead a horse to water" etc. I found an F2 countershaft in one of my boxes of junk today and was able to fit a 530 sprocket on to it, but it was a nice tight fit with no slop and no sideplay. I'd feel a lot more confidant with this set up than what you're describing. Up to you though mate, but at the very least I reckon the splines on your countershaft are gonna cop a hell of a hiding! Cheers, Terry. :-\
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I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline dpen

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Re: 78 CB750 front sprocket spacing?
« Reply #14 on: July 31, 2005, 12:22:30 PM »
On most trailbikes with this "floating" setup, the sprocket is a softer metal than the shaft.
The only movement is side to side, there is buggar all rotational movement.
As I said, I've done a fair few k's on this but you've got me interested.
I'm going to pull the cover & size things up just for the mental exercise.
« Last Edit: July 31, 2005, 12:33:13 PM by dpen »
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Offline CB750R

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Re: 78 CB750 front sprocket spacing?
« Reply #15 on: July 31, 2005, 01:23:01 PM »
Ok, I've asked a similar question before, but I have a 74 engine in a 77F frame, My front sproket, has two bolt holes, in it, but the only thing holding it onto the countershaft sprocket is two C-clips, is there something else that is supposed to attach to the sprocket to secure it? I've asked about the side to side play, and been told its normal, but its in excess of 1/8 of an inch, and I think thats kinda dodgy...   so little help?? a picture would be great!!!

Thanks
G
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Offline Terry in Australia

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Re: 78 CB750 front sprocket spacing?
« Reply #16 on: August 01, 2005, 01:45:11 AM »
Quote from: dpen on July 31, 2005, 12:22:30 PM
On most trailbikes with this "floating" setup, the sprocket is a softer metal than the shaft.
The only movement is side to side, there is buggar all rotational movement.
As I said, I've done a fair few k's on this but you've got me interested.
I'm going to pull the cover & size things up just for the mental exercise.

Good idea mate, at our age, mental exercise is about all we're good for, ha ha! Cheers, Terry. ;D
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I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline Terry in Australia

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Re: 78 CB750 front sprocket spacing?
« Reply #17 on: August 01, 2005, 01:55:06 AM »
Quote from: CB750R on July 31, 2005, 01:23:01 PM
Ok, I've asked a similar question before, but I have a 74 engine in a 77F frame, My front sproket, has two bolt holes, in it, but the only thing holding it onto the countershaft sprocket is two C-clips, is there something else that is supposed to attach to the sprocket to secure it? I've asked about the side to side play, and been told its normal, but its in excess of 1/8 of an inch, and I think thats kinda dodgy...   so little help?? a picture would be great!!!Thanks G

G'Day G, you're dead right mate, there should be a little locking plate that holds your sprocket onto the countershafr via the two little 6mm screws, and definately no "C" clips. What are you running, a 530 or 630 chain? Cheers, Terry. ;D
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I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline CB750R

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Re: 78 CB750 front sprocket spacing?
« Reply #18 on: August 01, 2005, 08:27:07 AM »
530 modern oring chain, mated to my FZR rear wheel.  Where the heck to I aquire a locking plate for the sprocket!!!

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Offline Bob Wessner

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Re: 78 CB750 front sprocket spacing?
« Reply #19 on: August 01, 2005, 09:02:47 AM »
If someone can verify we are talking about a splined plate held to the sprocket by two washered bolts and the same plate from a K0 will fit, I have a spare I can give you. It would include the two fastening bolts and their washers.
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Offline CB750R

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Re: 78 CB750 front sprocket spacing?
« Reply #20 on: August 01, 2005, 09:21:53 AM »
you da man!!  I'll PM my address to you.  question is, how does that plate hold the sprocket on the spline??  or will it be obvious when I see it??

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Offline Bob Wessner

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Re: 78 CB750 front sprocket spacing?
« Reply #21 on: August 01, 2005, 09:58:45 AM »
It will be obvious. The sprocket and plate accommodate the splined shaft. The only difference is that once the sprocket is on the shaft and then you mount the plate, you will have to rotate the plate a few degrees to get the bolt holes to line up. This locks the plate behind the splines on the shaft.
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Offline CB750R

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Re: 78 CB750 front sprocket spacing?
« Reply #22 on: August 01, 2005, 04:31:53 PM »
Thanks Bob, with out exagerating, your a life saver!!

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Offline Bob Wessner

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Re: 78 CB750 front sprocket spacing?
« Reply #23 on: August 01, 2005, 07:12:38 PM »
Let me know how it all works out when you get it.
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