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

[steam-powered man]

just looked at my bike for reference.  i have a 17inch drop-center rim running a 130-17 and have no clearance issues.  new chain, so tire is forward.   

first i'd check to see if the rim is laced off-center to the hub.  easy enough, just measure from each tire edge to the insides of the swingarm.   

with the axle pretty much even on both sides at the alignment marks, and at the beginning of the "chain stretch indicator" the tire shouldn't be that close to the end of the swingarm nor contacting the brake stay.  i think your chain is too short.  can't you add a few links to move the wheel back an inch?     

[edwardmorris]

What? You cant push the bike back and forward with the weight on it to really check for tight spots?

Tried that, but it is soo extremely difficult, as if I'm trying to push it with the brakes applied. I was half dead just rolling the beast 10 feet to get it inside the garage. Hasn't moved since. The seller told me the front brake was done for so I will be working on that this weekend. Couldn't do much during the work week unfortunately. Really wanting to get this one running.

[Stev-o]

Front brake is prolly stuck, quite common.  Read here.....


http://forums.sohc4.net/index.php?topic=44371.0

[PeWe]

I had Metzeler ME99 130/80-18 before without problem except very flat.  After reading this forum I understood that the fattest tires recommended to use on OEM rims: 100/90-19 front, 120/90-18 rear.

[Stev-o]

I had Metzeler ME99 130/80-18 before without problem except very flat.  After reading this forum I understood that the fattest tires recommended to use on OEM rims: 100/90-19 front, 120/90-18 rear.

OP has a 17" rear wheel....

[754]

Quick fix..
 Align chain on marks. IF it still rubs..
 Put bike on centerstand.. Turn tire while grinding edge of tire off with an angle grinder..

 Cheap..simple..quick..done

[MoMo]

What? You cant push the bike back and forward with the weight on it to really check for tight spots?

Tried that, but it is soo extremely difficult, as if I'm trying to push it with the brakes applied. I was half dead just rolling the beast 10 feet to get it inside the garage. Hasn't moved since. The seller told me the front brake was done for so I will be working on that this weekend. Couldn't do much during the work week unfortunately. Really wanting to get this one running.

If you own a dead blow hammer, hit the caliper with it-that will free the brake piston  so you can push it withou having a cardiac...Larry

[malcolmgb]

Quick fix..
 Align chain on marks. IF it still rubs..
 Put bike on centerstand.. Turn tire while grinding edge of tire off with an angle grinder..

 Cheap..simple..quick..done

I take it this is a tongue in cheek comment, should put a smiley in case someone takes it seriously.   

[Stev-o]

Quick fix..
 Align chain on marks. IF it still rubs..
 Put bike on centerstand.. Turn tire while grinding edge of tire off with an angle grinder..

 Cheap..simple..quick..done

I take it this is a tongue in cheek comment, should put a smiley in case someone takes it seriously.   

I think he was serious!

[754]

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.

[edwardmorris]

So, I managed to get the bike up on a couple of car jacks, and same as with my carb leak issue, some good news and a crapshoot of bad. Good part is that when jacked up, the rear wheel seems to be moving with little effort eventhough its grinding on the metal. Bad part is that eventhough I know next to nothing of these bikes, I can tell that the chain is not perfectly aligned. The rear wheel sprocket seems to be sticking out a little, while the engine side sprocket is further inwards. The chain has almost no slack so I'm guessing its too short like someone pointed out.

Also, I noticed that the wheel has significantly larger clearance with the swing arm on the left side, but is dangerously close to the swing arm on the right side. I took some pix but not sure how much help they will be because those are some really #$%*ty angles to snap from. I'm a bit relieved that its not the tire size, and I don't have to go hunting for once especially since the one on there seems almost new. I'm gonna go back out there now to see whats the story with the front brake.

[Stev-o]

Post a pic from the back at axle level  (towards front).

[edwardmorris]

Post a pic from the back at axle level  (towards front).

Took one, but its been thunderstorming and cloudy as hell so came out really #$%*ty even with a flash. Here are some that aren't as bad, but probably no help.

[TwoTired]

I find it humorous that there are two pages of "discussion", and the OP has never said which year and model bike he has.
I guess they are all the same in every way...

 

[edwardmorris]

I find it humorous that there are two pages of "discussion", and the OP has never said which year and model bike he has.
I guess they are all the same in every way...

 

Sorry about that, its a 72 CB750 K2. Some of the guys helping me out here have been following since I started posting and know much about it. Please follow the links in my sig if you'd like to catch up. I'm working on 4 different issues at this time. Goal is to get it running before end of this season, and short term goal now is to get it to start again on this long weekend.

[madmtnmotors]

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).

[754]

I knew it was a 750 by the seamed swingarm
 You have to make sure you do not have late style sprocket carrier with the 72 motor/frame.
 Makng that fit in the 72 swingarm may have led to the brake side axlespacer having been cut down , bringing the rubber closer to where it is rubbong.

[Stev-o]

I knew it was a 750 by the seamed swingarm
 

I think we all knew it was a 750 except maybe for one "expert". 

[scottly]

The sprocket on a K7/K8 wheel is mounted about 10mm further out than the earlier 750s. This can be corrected with an off-set sprocket.
Ed, you seem to have a bit of a Frankenbike; please give us the frame number and the engine number so we can help you figure out the best way to fit the parts you have into a proper motorcycle.
The K7/K8 bikes came with a 630 pitch chain, while the earlier bikes had a 530 chain. Measure the center-to-center distance of the pins in the chain: 530= 5/8", while 630= 3/4".

[scottly]

Here are some better pix with markings. Looks like the wheel is pretty centered, and there isn't much slack in the chain, so I guess its too big a tire. I will try and mount it up on two jacks tomorrow to get the rear wheel off the ground and see if its wobbling and rubbing on one spot or if it is constant contact.

In the first pic in this post, the spring on the brake rod is fully compressed. While unrelated to the rubbing issue, this is a symptom of worn brake shoes, or more likely the brake arm is one tooth off on the splined shaft. Ask Mooshie about that..

[754]

After reading your sticking brake thread,and reading grinding back wheel.
 I supect...
 Spacer missing inside sprocket carrier
 Wrong sorocket carrier
 Modded brakes side spacer...too short

.here is what you do.. Before trying to start it..
 Go over the entire bike, and see what you have and dont have..
 Sort everything out on it..

 But before that ..get a manual.. A real holdinyourhand flipthru the pages manual...because you need it.. Or better yet Hondaman,s book.

[edwardmorris]

OK here are some pix at the axis level looking straight to the front. Also some details on the rear wheel. I really hope its not a frankenbike. I found the engine number but can't find the frame number. Is the frame number same as the vin? Also, not sure what the spacers are exactly but I'm hoping the pix will answer that question. Again, pardon the naivity, today is only day 8 with the bike

[edwardmorris]

Some views on the other side

[754]

You mean you bought it without looking at the numbers?
 Dont post your location,that way a close by member may not be able to come over and help you..

..get a manual.. Start reading up on things here..
 Is this your first bike?

[edwardmorris]

You mean you bought it without looking at the numbers?
 Dont post your location,that way a close by member may not be able to come over and help you..

..get a manual.. Start reading up on things here..
 Is this your first bike?

Profile updated. I've already shared that I live in NW Indiana and few guys from Wisconsin have already asked about it. Believe me, I'd appreciate nothing more than someone experienced helping me out hands on. This IS my first bike, and I do have the VIN, what I wasn't sure was if the frame number was something different.