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

[Tugboat]

Progress report:

Took the sprocket-side spacer to a machinist dude I know and had him cut it down 7mm. Original size 25mm now 18mm. Result:





It still won't fit the chain adjuster on the RH side though. Probably going to have him cut 2-3mm off the brake-side spacer. 2mm might fit? 3mm is the width of the chain adjuster.

[madmtnmotors]

Progress report:

Took the sprocket-side spacer to a machinist dude I know and had him cut it down 7mm. Original size 25mm now 18mm. Result:





It still won't fit the chain adjuster on the RH side though. Probably going to have him cut 2-3mm off the brake-side spacer. 2mm might fit? 3mm is the width of the chain adjuster.

Does the caliper carrier serve as the spacer, or is the spacer seperate from the caliper carrier? If the spacer and caliper carrier are seperate, will this affect disk alignment with the caliper, or would the "floating" nature of the caliper acommodate this?

Also, if cutting down the brake side spacer does work, you may have to shim the sprocket out that final 3mm to complete the alignment of the sprockets, which should not be to difficult, and should leave plenty of the center hub still supporting the center of the sprocket.

[754]

 either Mill some off the OUTside of the caliper mount or get the later swingarm and Axle...

[Tugboat]

There's a spacer between the caliper and the hub.. you can see it on pic #3.. kinda mushroom-shaped. Disc alignment... hmmmm.. hadn't thought about that.

[754]

 looks like you have early axle adjusters, if you do they may ber thicvker than late ones. I s that an early F swingarm or 77/78 style? I cant tell you what the disc brakeside should have, but make sure your caliper is aligned to the rortor..

[Tugboat]

'76 F swing arm

[Tugboat]

Got it today and put it on. Again, stock '76 750F hub, carrier, spacers, swing arm. Here's the skinny:

Not gonna be able to use the chain guard




1/2" clearance between sprocket and shock. I did the math after measuring the width of the chain, and I'll have about 1/8" clearance once it's installed.. maybe slightly more. (note: sprocket still has about 2-3 mm before it's fully seated on the carrier... see below)




It would seem that the inner diameter of the sprocket is slightly too small to just tap in place with a rubber mallet. Is this how all new sprockets are on the carriers? Tight like this? Can I just torque it down? I'll call CycleX tomorrow and ask if they've ever had fitment problems.

[seanbarney41]

I just got one too...slides right on early k sprocket carrier, I am not running a chain guard so no problem there but I am running cb900f shocks which are fatter in the danger zone...will have to grind some clearance or find some other shocks...will get pics soon if anyone needs 'em

[Spanner 1]

O.K.... my head is spinning at this point  ... anyone else ?

[seanbarney41]

Spanner, I am using a 77-78k motor in a early k bike...need the 10mm offset sprocket to align with different countershaft set up of the 77-78k engine...yes it's a long story but this sprocket gets me back on the road sooner than rushing through a rebuild of my early k motor...

[Tugboat]

Just talked to the guy at CycleX. He said they've never had fitment problems and suggested that maybe there's some chrome build-up that's not letting this seat properly? Hmmmmm... You think it's okay to put the nuts on and torque it down and see what happens? Don't want to mess anything up....

[Really?]

If you have to force it on, it might be a beotch getting it back off.  Can you sand a bit of either piece down enough to make it go on a bit better?

[754]

 Dont force it on , use a flapper wheel and die grinder, open up the sprocket hole..

[lucky]

A lot of confused talk about all of this fitment problem.

FIRST the rear sprocket teeth MUST line up with the front sprocket
AND... the rear wheel MUST be centered in the frame. At the same time

So get that right FIRST just use the wheel ,axle and sprocket. Nothing else.

NOW.. When the rear wheel is lined up AND the sprocket is in the correct position THEN you measure the space that needs to be filled in on the chain side of the wheel.
That would include the chain adjustment stop piece. Put those spacers on the bike.

NOW you can move to the other side of the bike and measure the spacers needed for the non chain side.

Use a thickness gauge if necessary. NOT a carpenters tape measure.

All the parts need to be CLEAN and free of grease, dirt, and corrosion.

[lucky]

Dont force it on , use a flapper wheel and die grinder, open up the sprocket hole..

How would you keep that hand grinding concentric?
Very poor advice in my opinion.

[Retro Rocket]

Dont force it on , use a flapper wheel and die grinder, open up the sprocket hole..

How would you keep that hand grinding concentric?
Very poor advice in my opinion.

A flapper wheel will only clean up the surface, you need to stop talking to everyone like they are idiots here Lucky, Frank {754} knows his stuff...

[lucky]

I am not being condescending at all.
I am just saying what I would do if it was me.

It is just my opinion and it can be disregarded if not needed.

[754]

 I suspect its just a bit of chrome build up in the sprocket bore..probably only on one edge.. chrome tends to do that..

[Really?]

754 is perty smart when it comes to these 4's.  He is a little nuts about kickstarters though. 

[Tugboat]

Installed for real now, with new bearings. Chain goes on tonight. Using calipers I measured 9/16" clearance.

[seanbarney41]

mine came out with much less shock clearance...of course with the cb900f shocks, which are fatter right by the chain.  With the cb900f shocks and a well worn sloppy non o-ring 530 chain, it would just clear by a mm or two, then the chain would wander back to the outside of the sprocket and contact the shock gently.  So I did same manglin'...Tugboat, I never quite gathered, do you have a '77 or an early k frame/swingarm?.  Here is what things look like with a 77/78k motor in an early k frame and early k everything else too(except shocks )...

[seanbarney41]

Of course now, I need a 530 front sprocket for a 77-78k motor which originally used a 630.  First attempt is a fail...ordered JT through parts unlimited 'cuz my bud gets me dealer cost at the dealership he works at.  Somehow I just ended up with a front sprocket that is just like an early k, which is too thick for the 77/78 countershaft mounting...I am guessing CycleX has what I need here too.  Anyway, I know they were out there because that is what the motor had on it when I got.  Unfortunately, the front sprocket is about shot.

[Tugboat]

I have '76F1 frame & swing arm & hub.. only thing non-stock is the rear sprocket (and now the front sprocket, changed @ same time). Mine is with 530 non-o-ring chain. Will order an o-ring chain next week if this all works out. Pics here in a bit once I take some links off this chain. Thanks for the update & the pics - you're not kidding! You have way less clearance than I do @ rear shock.

[Tugboat]

The verdict:

10mm of clearance between the chain and the LH shock. Also 10mm clearance on the bottom between the chain & the frame. Had to cut off the front chain guard mount but plenty of clearance all around. This is with a regular non-o-ring 530 chain (110 links).









Going to upgrade to a 530 o-ring chain and will probably end up with 5-6mm clearance. Incidentally, that whole thing about my wheel not spinning freely when the axle bolt is torqued down? Yeah.... see my other thread.

[754]

 Sean I think the front sprocket will work, just use thick washer and loctite the bolt