Topic: Rear Wheel : This just made my heart sink.

[malcolmgb]

I am serious..you can take an 1/8 inch off, you can shim brake Rod slightly. The 77/78 has a tubular one, it may have a bit of offset but the length/ mount may be different.

How do you take 1/8" off a rubber tyre with an angle grinder for the whole circumference, accurately?
I was always taught to tackle the cause not the symptom.

Whoa!! this is more scarey than your profile pic  I'm out of here, and Lloyd I didn't know what model bike it was and didn't think I needed to for this comment. 

[TwoTired]

Didn't the CB750K use an 18 inch rear spoke wheel until the 77-78 K models?

What combination of parts does the OP have?

Perhaps you other "experts' can tell him?

[754]

There is obviously some mismatched parts it appears.
 As for grinding the tire..it seems to horrify some people, will try to explain, a bit..
 I did not look into, the tire size fit, alignment etc,when i mentioned it, because it will work. unless you need/use that edge.  We do it on bikes with oversize tires.
 Most folks can find an angle grinder, but not as many can make their own spacer on a lathe.
 Get someone to turn the wheel while you grind, done right, the wheel might turn on its own driven by the grinder.
 Left alone the bike would take some off anyway, but not the extra clearance.
 
 The bigger issue is the bike needs a good going over, andthe owner has homework to do..

[setdog]

Are you missing the axle spacer on the right side?

or incorrect size spacer?

how is the tire - swing arm gap on the left side?

check out the rear axle parts fiche and make sure you have all the correct parts in place and in the correct order etc...

and what are odds the chain is incorrect for this bike and too short?  i dunno im just thinking out loud.

[edwardmorris]

Looks like you're tire is rubbing the rear brake stay. Make sure the front mounting position of this stay arm is mounted BETWEEN the two mounting tabs on the underside of the swingarm. If this stay arm were mounted INBOARD of the two mounting tabs (instead of captured in between), this may shift it far enough towards the tire to cause it to rub. I would also check that the rear wheel spacers are in the correct order. If not, this could shift the wheel to one side more than it should. Don't know the spacer thickness/order of the earlier models, I think the K7/K8 were different (my forte).

I checked this out, looks like it is mounted in between, was very hard to look from the left side, but have a good pic from the right side. Will mounting it OUTBOARD make enough room to stop rubbing? Also, looking at the assembly it doesn't seem like there is much room to move it more than a few mm either side anyway, but again, I'm the noob here I am probably wrong . I am going through the manuals now to learn as much about the rear wheel assemble so I can try and answer some questions asked by the experts instead of replying with pix all the time

[madmtnmotors]

Will mounting it OUTBOARD make enough room to stop rubbing?

No. Just be sure it's mounted correctly and continue to try and resolve the real problem, instead of creating others...

I'm guessing the rear wheel hub assembly has been cobbled together with a mish mash of uneven parts. I would pull the rear wheel and lay out the components from one side to the other and start measuring each piece so we can figure out what's out of place.

Check reply #2 in this thread, keeping in mind that the earlier model spacers may be a different overall length, but I believe the order of components is the same:

http://forums.sohc4.net/index.php?topic=103860.msg1161713#msg1161713

Also keep in mind that the K7/K8 sprocket hub is 10mm taller than the early model. You will need to determine whether you have the correct sprocket carrier as well.

[scottly]

The chain appears to be VERY close to the shock; this is more confirmation that you have a K7/K8 17 inch wheel mounted on an earlier bike. As I stated before, an off-set sprocket *may* solve the chain alignment problem. The issue with the tire rubbing on the other side might be helped by fitting a longer chain, or spacing on the brake strut. Have you measured the chain yet, to determine if it is 630, like the K7/K8, or 530, like the earlier bikes?   

[edwardmorris]

The chain appears to be VERY close to the shock; this is more confirmation that you have a K7/K8 17 inch wheel mounted on an earlier bike. As I stated before, an off-set sprocket *may* solve the chain alignment problem. The issue with the tire rubbing on the other side might be helped by fitting a longer chain, or spacing on the brake strut. Have you measured the chain yet, to determine if it is 630, like the K7/K8, or 530, like the earlier bikes?   

Chain is 5/8" center to center on the links. Vin is CB750-2007003. Eng is CB750E-2014686.

[cameron]

754 has mentioned it.. but I would like to second this:

Your bike is not roadworthy. Get it started if you want.. but if I were you, I wouldn't take that thing out of the garage until you have totally disassembled and reassembled the rear end.
Get a manual, and see if you can make what you have match what you SHOULD have.

There are no hidden secrets.. you just have a little bit of a learning curve ahead of you.
 Pull that thing off.
Count the parts.
Check and double check the placement of every shim, ever bolt and every nut.
Once you KNOW its correct.. it will actually BE correct.

[edwardmorris]

754 has mentioned it.. but I would like to second this:

Your bike is not roadworthy. Get it started if you want.. but if I were you, I wouldn't take that thing out of the garage until you have totally disassembled and reassembled the rear end.
Get a manual, and see if you can make what you have match what you SHOULD have.

There are no hidden secrets.. you just have a little bit of a learning curve ahead of you.
 Pull that thing off.
Count the parts.
Check and double check the placement of every shim, ever bolt and every nut.
Once you KNOW its correct.. it will actually BE correct.

Desperately waiting for a full center stand assembly so I can take the rear wheel apart. Have some leads, but still not a complete center stand. Its a start I suppose....

[754]

Use your sidestand and a wooden block..or blocks

[LesterPiglet]

Or a jack under the sump. Even though my four pipes run in the way I can still jack it up using a piece of wood for a buffer.

[edwardmorris]

Use your sidestand and a wooden block..or blocks

I think it came with a bobber stand so it leans too far down. I will try and get it up somehow, although progress may be slow as work weeks starts in a few hours. Made some progress on the stuck break front so happy about that, still has to be properly bled and get the pad and piston to pop out.


I know this may sound like a chiropractor diagnosing cardiomyapathy but is it at all possible that the wheel/spokes are warped from being parked for prolonged periods on a crappy bobber stand?

[fastbroshi]

I won't say it's not possible but I've never heard of it happening.  I'm with Cameron.  Try to identify exactly what you have parts-wise and what that will help zero in on the actual problem.  That's 50% of solving it.

[edwardmorris]

Still hunting for a wheel, center stand should be shipping out soon. I was doing what was suggested here and taking a close up look at everything the bike is missing, and something else made my heart sink. The frame has been cut right under the gas tank. So, no matter what I do to it, it will never be a "complete" original resto. Very discouraging. My list of parts wanted keeps growing the more I look at it. Which is fine, but stupid stuff like ppl cutting of body parts is just terrible.

[ekpent]

Did they cut the two tubes that run alongside the main backbone ? If the left enough of a stub on each end you may be able to fabricate a 'frame kit'. PO probably cut them out to work on the engine easier.

[Stev-o]

That sux about the frame cut.  Hope that Eric is right.
Post up a pic of the cut

[edwardmorris]

Here are some of the frame, and my new fuel lines. Unrelated, but how do you guys deal with air gaps in the line? I keep having to waste gas by letting it drain till the bubbles get out. Is there a better way to get rid of them? Coz I know it won't start because the gas flow is hindered.

[Tews19]

That is rough... Hopefully someone can chime in if you can repair that.. Can you measure how much was cut from each section? I wonder if you could use the frame that was cut from another frame?

[Stev-o]

Wow, he really buggered up that frame, WTF?
I would not ride it like that. Look here to learn about a frame kit, add this to your list.


Your fuel lines look very long.  Your fuel system is gravity fed, the lines need to be as vertical as possible.  I never have "air gaps".

[Irukandji]

Here is some picts to see how to repair frame. Can be done much more simple if you can find this other method in the forum. This kit may be available from a member on the forum.

http://www.vinmoto.org/gallery/v/VinMoto-Garage/album03/Godfferys-Garage-123/RVs+750/Fraim+Kit/

[scottly]

Just curious; what did you pay for this bike? It appears to be a bit rough for a restoration. What does the front of the frame on the left side look like? If the stub of tubing is the same as the other side, a frame kit will still work. BTW, there is a non-stock ignition coil zip-tied to the backbone...

[Stev-o]

Just curious; what did you pay for this bike?

And who did you buy it from?   Were you aware of all the modifications made on this bike??

[Tews19]

Yeah I am with Scottly... That bike needs a lot of work.. To much work for a resto IMHO.

I know you stated the wheel was locked, how did you load it? I would contact the seller just to #$%* if he never told you about the frame being cut. ( He most likely will be like whatever and hang up).. Most likely the engine needed work on the head and now you may have a lot more on your table then just air bubbles in the fuel line...

[edwardmorris]

Paid (now regrettable) $700 total after getting it titled in my name and paying state tax, and it was delivered to my home. I bought it form a guy who lives two towns south of where I live. He loaded and unloaded it 10ft from my garage. His listing did say that the clutch needed adjusting and the front brake was done for. Of all the listings on craig's list, this was the cheapest one with an actual running engine. Anything cheaper was either disassembled or missing even more parts and a ceased engine was a given. This is my first time attempting a bike rebuild so I was hopeful that if I didn't have to deal with a ceased engine, I could actually do it since I am not terrible with the body's mechanical work. I really hope I can still get it out on the road, at least get one maybe two good seasons out of it. If I must rebuild the engine, then so be it. For now, I guess the immediate priority would be the frame. I will post some better pix taken in daylight. Also, what to do with the non-stock whatever POS is on there now? Suggestions?