Topic: A few wheel and tyre questions cb750 K1

[cakey]

Bikes been sitting for 18 years and I'm restoring her. Originally I was going to get the tyres taken off the rims and then new spokes and bearings. Today I got the tyres taken off ready for new rubber. First question is are these sizes original? I was going to get a set of Continental classics but the rear size in the continental set is 110/90 - 18 but these are the two sizes that came off. I would like to stay original.
Rear : 120/90 - 18
Front: 100/90 - 19

Then I took the rims home to start stripping down. No probs there other than I cannot get the bearings put with my home made blind bearing puller. The bearings are pretty frozen so I will need to check around town and see if anyone has a bearing puller that will work.

Then I couldn't help myself and thought I would throw a bit of detergent on the rim. Discovered that the rims appear to be chromed. I thought they were aluminium and I was going to rub back and polish. But a bit of detergent and a scoured and polish should bring them back pretty good I think without having to go the new spokes.

My question with this is I am toying with the idea of taking them to my Old Motorvehicle Club where they have a big blasting unit with fine sand. Anyone ever used a fine blasting medium to clean up the centre hubs? The hubs appear to be aluminium and have the normal anodised look.

Thoughts anyone?

The pics show

The hubs
The home made bearing puller
A bit of the rim I cleaned and discovered the chrome

[cakey]

Some more pics

[Henning]

My advice is stick with the stock tyre sizes, which are 4.00-18 and 3.25-19. I currently have a Continental 120/90-18 and a 100/90-19 on my 750 K1, and the handling is somewhere between rubbish and scary. Plus, the rear tyre touches the ground when on the centre stand, making greasing the chain a pain, and you can't get the front tyre out without removing the front mudguard. Maybe it will work out better for you, but it's an expensive mistake if not.

Here's a snap of my new stock sized ready-to-install Heidenau's...

[Bankerdanny]

I don't know about tyre sizes, but for tires, the 110/90 and the 120/90 kind of split the difference compared to the OEM tire, which as Henning notes was not a metric sized and I think techincally was a 100 aspect (height and width about the same). I think the 110/90 is slightly narrower and the 120/90 slightly wider.

If you check the site for the various manufacturers you should find specs on actual width and also circumference. There are a few companies that still sell 4.00-18 street tires, so you should be able to get the data for this OEM size and compare to the other metric sizes.

[Johnie]

I have never had a wheel bearing frozen. Just to clarify, there is a spacer tube between the bearings. Push the spacer to one side so you can get at the bearing edge. I have always used a long flat punch and hammer to get them out. Just work your way around the bearing and it will pop right out. Once the bearing and spacers are out straighten the tang on the spacer that you bent when you pushed it to one side. Don't forget to put that spacer back in too. Good luck with it.

[Mini Mo]

Do not sand blast those hubs. Even with fine sand it will etch them, leaving them dull and they will be a nightmare to keep clean. Spokes are cheap. Break the wheels down, hit the outer portion of the hubs with some medium scotchbrite and re-lace them. It's amazing what clean rims, brushed hubs and new spokes does for the overall look of these bikes.

[Stev-o]

Yes, the hubs are aluminum but not anodized.  +1 would look great polished. 

[cakey]

Thanks guys. Really appreciate the feedback. All my questions answered.

[LesterPiglet]

To answer the question that was overlooked. The rims are chromed.

[Grnrngr]

I've never had a wheel bearing freeze on a bike, but I have had it happen in a car, no fun. I have had a few wheel bearings DISINTEGRATE on my bike, and by God's good graces, did not lock a wheel. One of my parts bikes appears to have damage that could have been caused by a locked up front wheel, damage to the gauges and scrapes on the tops of the bars like it locked up and flipped over. Bearings are cheap, change them if they are suspect.

[jonda500]

I don't know about tyre sizes, but for tires, the 110/90 and the 120/90 kind of split the difference compared to the OEM tire, which as Henning notes was not a metric sized and I think techincally was a 100 aspect (height and width about the same). I think the 110/90 is slightly narrower and the 120/90 slightly wider.

If you check the site for the various manufacturers you should find specs on actual width and also circumference. There are a few companies that still sell 4.00-18 street tires, so you should be able to get the data for this OEM size and compare to the other metric sizes.

The 110/90 in some brands is too wide for the standard front mudguard on these bikes- I had to relocate my brake line hook to the outside of the mudguard mount to make a 110/90 metzeler lazertec fit my bike without rubbing

[cakey]

Got the bearings out yesterday which was great using same process as mention by Johnie. Someone up here suggested using a pin punch so I went and bought a set at the local store and the different sizes worked very well. I was able to get more grip on the bearing with the pin punch than the screwdriver.

Definitely decided on going with the stock sizes rather than the metric tyre sizes. I am really glad I asked the question because the guy fitting my tyres almost talked me into the metric and by the sounds of it that could have been a problem. All I need to do now is to find out if the stock size is available.

Thanks guys