Topic: CycleX 10mm offset rear sprocket - '76 CB750F

[Tugboat]

<<edit: was "Anybody ever bought offset rear sprocket from CycleX?">>

Looks like this is going to be the cheapest way out of my current situation IF it has the requisite clearance between it and the rear shock, and if it's 530 pitch. Anyone ever used this? At the bottom of the page, p/n CS-015

http://www.cyclexchange.net/Chain%20Sprocket%20Page.htm

[754]

 Cheapest way out.... 4 10mm spacers.. about 20-25 bux to get made up...

[Tugboat]

Well, I could use new sprockets too so I'm trying to kill two birds, dig?

[madmtnmotors]

Cheapest way out.... 4 10mm spacers.. about 20-25 bux to get made up...

Spacers raise the sprocket perilously close to the top of the center(ing) hub. Doesn't leave much of the center hub for aligning/supporting the center of the sprocket, leaving only the studs to align and support the sprocket.

Looks like this is going to be the cheapest way out of my current situation IF it has the requisite clearance between it and the rear shock, and if it's 530 pitch. Anyone ever used this? At the bottom of the page, p/n CS-015

http://www.cyclexchange.net/Chain%20Sprocket%20Page.htm

I would call to confirm. The description indicates that the sprocket is not available, that they now make an offset sprocket carrier instead. This implies that you would be able to use a standard sprocket with their offset carrier (adapter?). Again, I would call to confirm.

[FrankenFrankenstuff]

Am I silly to think that the farther you go out from stock, the more stress there is on that seal area where the shaft comes out from engine? I had made an alloy prototype for my 550 front sprocket. Dang 180 rear tire was a bad idea.

http://forums.sohc4.net/index.php?topic=70436.msg782070#msg782070

[Tugboat]

The '77K motor on my bike is already 10mm further out than the earlier K bikes... ergo my need to line it up right with an offset back sprocket. BTW, CycleX is selling these on ebay so I think they're still available. Will report back after I call 'em this afternoon.

[754]

 I am not sure if you missed it, but 77/78 casrrier and greasy spacer...or spacing your sprocket..will all get you what you need.. I would use the offsets for huge tires..
 Frankenbike, you should conside outboard sprocket support, hard to do on 750 but easier on most other bikes..

[FrankenFrankenstuff]

"outboard"? My bike is dead in the water because the....frame is now in the way of where the chain needs to be in order to clear the tire. Maybe I could incorporate a steel support into the frame? That is right at a joint in the frame though.

Sorry about the threadjack but.....its all kind of related right?

[754]

 You will have to deal with the frame, cut 1/2 out, or dogleg section.... or the easy way.. just run the wheel a bit off center..wont be perfect but works.
 How much are you looking at ofsetting.. around 20 or 25mm ?..bbl..

[Really?]

Good info on the carriers but it looks like they they just talk about the carrier, I see no place to order or a price.  Too bad the offset sprockets are only 46 tooth.  I would want the offset sprocket to be 48 tooth. Prolly still need the spacer if you switched to a 77/78k swingarm - me guessin'

[Tugboat]

@754 - I'm doing this to avoid having to buy not only new sprockets & a new chain but a different carrier, spacer, axle & swingarm as well. With the offset rear I can use my stock 76F hub/carrier/spacer/axle/swingarm setup and save myself about $150. Plus, nobody has been able to confirm that the 77/78K carrier/spacer/axle/swingarm setup would work on an older F frame & hub. It should in theory, but noboby has said they've done it before.

I just called and talked to a dude @ CycleX.. they do indeed have the offset sprocket in stock, and only as a 46-tooth. He had no idea what I was talking about when I mentioned that they had an offset carrier listed on their site.

On another note, I currently am running 17-tooth in the front, 48 in the back for a gear ratio of 2.82. With the new 46-tooth for the back, if I get a 16 for the front that will make my ratio 2.88 which is pretty close. Will that extra .06 make any difference as far as rpm's go?

[754]

 A very long time ago I had a 74 cb 750, put a 77K in it, then I noticed sprocket rubbed on only one side, so I realized I had to change spacing. Usedc a late carrier and inner spacer that I had. Far as I know it all fit in the 74K swingarm. I probably trimmed a spacer or got one made for the carrier to swingarm spacing, or just used the early one but it fit.

[Retro Rocket]

A very long time ago I had a 74 cb 750, put a 77K in it, then I noticed sprocket rubbed on only one side, so I realized I had to change spacing. Usedc a late carrier and inner spacer that I had. Far as I know it all fit in the 74K swingarm. I probably trimmed a spacer or got one made for the carrier to swingarm spacing, or just used the early one but it fit.

+1   Just use a K7-8 rear sprocket carrier and spacer...

[madmtnmotors]

I will measure the 76F swingarm width as well as the 78F swingarm width tonight and post the results here. We'll get this figured out yet!

[754]

 If the offset sprocket will fit so will the K7 carrier, just may mean thinner outside spacer..

[scottly]

On another note, I currently am running 17-tooth in the front, 48 in the back for a gear ratio of 2.82. With the new 46-tooth for the back, if I get a 16 for the front that will make my ratio 2.88 which is pretty close. Will that extra .06 make any difference as far as rpm's go?

The K7 has a different transmission. The K7 had a 15/41 sprocket combo (2.73).

[madmtnmotors]

As expected, the 78F swingarm is 10mm wider than the 76f swingarm. So I see a few options:

*77/78 sprocket carrier with longer stepped spacer and modified (shorter) outer spacer with the 76 swingarm
*77/78 sprocket carrier with 77/78F swingarm. An interesting feature of the 78F is that the left (sprocket side) shock has a longer shoulder on the top stem that shifts the top of the shock outboard about 8mm to better align with the wider swingarm.
*Offset rear sprocket, everything else stays the same.

Did you ever figure out why the rear wheel would not turn after torqueing the axle?

I've just picked up a 78F with the opposite setup, in that some PO swapped in a 76K motor with no accomodation for sprocket alignment. Needless to say the chain has a LOT of lateral (side to side) flex in it now...

[seanbarney41]

I love this place...I was just trying to figure this out on another thread...I am trying to use a 77-78k motor in a 75k frame...this 10mm will solve my sprocket alignment problems?  ...if so...Hooray!

[Retro Rocket]

I love this place...I was just trying to figure this out on another thread...I am trying to use a 77-78k motor in a 75k frame...this 10mm will solve my sprocket alignment problems?  ...if so...Hooray!

Yep, the k7-8 sprocket carrier will do it for you Sean {10mm wider}, i am not exactly sure what spacer to use but i suspect the 75K spacer will suffice....
You may have to get a K7-8 spacer and alter it to match, which shouldn't be too hard....

[seanbarney41]

I love this place...I was just trying to figure this out on another thread...I am trying to use a 77-78k motor in a 75k frame...this 10mm will solve my sprocket alignment problems?  ...if so...Hooray!

Yep, the k7-8 sprocket carrier will do it for you Sean {10mm wider}, i am not exactly sure what spacer to use but i suspect the 75K spacer will suffice....
You may have to get a K7-8 spacer and alter it to match, which shouldn't be too hard....

...and I think I know just where to get a k7-k8 sprocket  carrier too...will report back if so

[madmtnmotors]

I love this place...I was just trying to figure this out on another thread...I am trying to use a 77-78k motor in a 75k frame...this 10mm will solve my sprocket alignment problems?  ...if so...Hooray!

Yep, the k7-8 sprocket carrier will do it for you Sean {10mm wider}, i am not exactly sure what spacer to use but i suspect the 75K spacer will suffice....
You may have to get a K7-8 spacer and alter it to match, which shouldn't be too hard....

...and I think I know just where to get a k7-k8 sprocket  carrier too...will report back if so

The K7/K8/F2/F3 swingarms are 10mm wider than the earlier models. To use the later model sprocket carrier you will need the longer stepped spacer (that goes behind the sprocket carrier) and then would need to modify the outer spacer (shorten) in order to retain your original swingarm. Bear in mind, that if you opt for the wider (K7/K8) swingarm, the top shock mount on the left (sprocket) side of the frame has a longer shoulder (8mm longer) to align better with the wider swingarm. May not matter, but it is a difference I noticed on the models in my growing collection.

[Tugboat]

I actually found a guy yesterday here in Nashville that had a 77F he's parting out. Went and picked up the rear comstar in ok shape and some other goodies for pretty cheap. When I got home I swapped carriers and it does fit, though not tight. It has some slop to it. Guess I need to swap the cush drive parts out too.

Anyway looks like I'm going to need the swing arm as well - should've gotten it while I was there but it's not in great shape either. Will need at least a wire wheel & some paint.. will try to pick that up at lunch today, along with the axle stoppers & longer (I assume) axle.

The only spacer that is different between 75/76 F0/F1 and 77/78 F2/F3 is the stepped spacer that goes between the carrier and the hub.. the rest are the same.

On a related note, no I never did figure out why my wheel wouldn't turn freely when torqued down. I plan on replacing all of the bearings, though, and making sure everything is seated correctly. Hopefully all of this will pay off.

[madmtnmotors]

I actually found a guy yesterday here in Nashville that had a 77F he's parting out. Went and picked up the rear comstar in ok shape and some other goodies for pretty cheap. When I got home I swapped carriers and it does fit, though not tight. It has some slop to it. Guess I need to swap the cush drive parts out too.

Anyway looks like I'm going to need the swing arm as well - should've gotten it while I was there but it's not in great shape either. Will need at least a wire wheel & some paint.. will try to pick that up at lunch today, along with the axle stoppers & longer (I assume) axle.

The only spacer that is different between 75/76 F0/F1 and 77/78 F2/F3 is the stepped spacer that goes between the carrier and the hub.. the rest are the same.

On a related note, no I never did figure out why my wheel wouldn't turn freely when torqued down. I plan on replacing all of the bearings, though, and making sure everything is seated correctly. Hopefully all of this will pay off.

Bear in mind, that if you opt for the wider (F2/F3) swingarm, the top shock mount on the left (sprocket) side of the frame has a longer shoulder (8mm longer) to align better with the wider swingarm. May not matter, but it is a difference. Maybe snap some picts of the 77F frame while you're there, or take some measurements to compare with your 76F and you'll see what I mean.

[Tugboat]

Ahhh! I see what you're saying.. that upper mount has to stick out a little more to compensate for the extra width at the bottom. Hmmmm.... So maybe I should look into cutting down the sprocket-side spacer instead? If the swingarm is 10mm wider, then the spacer should be cut down 10mm? When I tried to install the assembly last night it would just barely not fit without the chain adjusters, which are 3mm thick on each side..

[754]

 You can probably spack out the top of shock a few millimeters on the earlier frame, as long as 3/4 of the shock is on the stud..  you can build a step spacer for the overhanging side, then the shock will be supported..  will get a bit tight for the nut..

Tugboat, cut 6mm off your outer axle spacer and you may need a custom chainguard.. The 77 swingarm is slightly longer and will lower yopur bike slightly. It casn work with your original swingarm..