CB750F1 Wheel Bearing Info

[cravacor]

Hello all,
I'm replacing the wheel and head bearings on my '76 CB750F. Here is what I have found re. the bearing sizes and Honda part numbers.

Front wheel bearing x2
Honda Part Number per Western Hills: 96150-63020-10 BEARING, RADIAL BALL 6302UU
Common size: 6302
Dimensions: 15mm x 42mm x 13mm
2RS or 2RSH (after 6302)=Rubber seals fitted to both sides of the bearing

Rear wheel bearing brake side
Honda Part Number per Western Hills: 96140-63040-10 BEARING, RADIAL BALL 6304U
Common size: 6304
Dimensions: 20mm x 52mm x 15mm
2RS or 2RSH (after 6302)=Rubber seals fitted to both sides of the bearing

Rear wheel bearing drive side
Honda Part Number per Western Hills: # 96140-63050-10 BEARING, RADIAL BALL 6305U
Common size: 6305
Dimensions: 25mm x 62mm x 17mm
2RS or 2RSH (after 6302)=Rubber seals fitted to both sides of the bearing

Head bearings
Upper: 26mm x 48.5mm x 15.2mm
Lower: 30mm x 50mm x 14.4mm


Using these sizes, you can buy quality bearings made by SKF, Timken, FAG, Koyo and others for better prices than Honda OEM or Chinese "balls" bearings.
Stainless steel seals and ceramic balls can be had as upgrades as well.

[TOOLS1]

It's nice of Honda to put the size dimensions, and common part numbers of their bearings and seals in their parts fiches. I always call the local bearing distributors and ask if they have them before ordering off the internet. A lot of times they will have them in stock, for about a 1/3 of the price of the dealerships.
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[cravacor]

I checked with the local bearing house. Apparently Timken doesn't make a tapered roller in the correct size for the head bearings. Closest they have is 25mm x 47mm for the top and 29mm x 50.29mm for the bottom.
Does anyone know of any reputable manufacturers that make a tapered bearing that will fit (other than All Balls)?

[TOOLS1]

I always just get the tapered roller bearing kit for the steering head at Cycle-X. You get the bearings, seals, and spacers. Just so much easier then trying to source all the parts separately.
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[cravacor]

Thanks, Tools. I like Cycle-X's return policy:
"If you install products with a hammer and want to return them (don't bother)"
What if the only tools I own are hammers?!?

[TOOLS1]

That would make you a carpenter.
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[cravacor]

Is your KZ750 a four or a twin? My first street bike back in the day was a KZ750 LTD twin. Fun bike, I rode the wheels off that thing.

[cravacor]

I've looked through Cycle-X website. The only head bearings I found were for DOHC bikes which are different size.
I found K&L Supply lists a kit that is made in Japan, their P/N is 31-5830, it includes upper & lower bearings/races and one washer. No seals. The kit is branded Parts Plus and their P/N is SSH750. This looks like my best bet.

[TOOLS1]

Right here on this page http://www.cyclexchange.net/fork_tubes_and_accessories.htm Part# FR-304.
I have had 3 KZ 750s. All were are the four cylinder. 2 of them were stock original, but the one I still have has been (well is being) customized. Swing arm moved 4 inches back, and a mono shock installed. Front lowered 3 1/2 inches. Trying to make it look like a modern version of a board track racer.
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[cravacor]

I have spent a lot of time over the last few days acquiring as much knowledge as I can about the head bearings. I read a very, very long thread over on the other forum that talked mostly about the problems associated with the installation and fit of tapered bearings. It seems the core issue is there is no tapered bearing that is an exact fit for our bikes. The tapers that are available apparently have shaved down races to decrease the OD so they will fit in the frame, but they are still too short on the bottom, requiring shimming and too tall at the top so they stick up over the frame a few millimeters and cause fitment issues with the top tree. If you have a K this is not as big of a deal because you can just shim up your fork ears. For the F with stock headlight bracket, this is a real issue because the spacing between the speedo bracket & lower tree is critical for the headlight bracket to fit correctly.
All this brings me back to a question I have seen very little or nothing about.
Why not just install new OE style balls & races?
I see the races are a bit pricey, but the balls can be had in the aftermarket for quite cheap. I understand there may be some performance benefits of the tapers but they do seem negligible for normal use and the improper fit and increased stiction seem to outweigh the minor performance improvement.
Other than the possibility of the balls peening the races (which is typically a result of abuse, wheelies, jumping, being tied down too hard while trailering, or whatever) I really don't see what's so bad about the stock setup.
I'd really like to hear what the wizards have to say on this matter. I've heard anecdotal evidence about the much improved handling after installing tapers, but a lot of that could be the result of simply going from old, dried up bearings & peened races to new bearings, not just the change from balls to tapers.

[TOOLS1]

"I've heard anecdotal evidence about the much improved handling after installing tapers, but a lot of that could be the result of simply going from old, dried up bearings & peened races to new bearings, not just the change from balls to tapers. "

I agree with this statement wholeheartedly. The stock ball bearings when properly greased, and adjusted, are well suited for the application. The tapered roller bearings are really only necessary when the rake is increased for longer front ends, or high performance applications like racing. However I have installed several sets of tapered roller bearings into the CB 750's and never had any problems with clearance. The first set I installed, I put a spacer on the bottom bearing, and then noticed it was not necessary. I then had to carefully drive the bearing of, and remove the spacer. Since then I have never installed a spacer on any of them. If you do a search for "POW-MIA" it will bring up a thread where I show the installation of tapered roller bearings.
As for reusing the ball bearings, I have done this on several bikes. I just clean the bearings and races, then inspect them for wear/damage. If everything looks good, I grease them up, and install them.
TOOLS

[shinyribs]

Honda still uses ball bearings today. They finally caged them, but they use balls. All the 2000 and later GSXR front ends I've fiddled with have used caged balls,too. Ball bearings actually impart much less friction in to the system than needles do.

And I agree on the fitment issues. The worst part of it is the fact that the upper bearing eventually runs un-sealed. Nothing at all wrong with the stock setup.

[cravacor]

I appreciate the responses, gentlemen.
Someday I'll build a custom machine but with this F my goal is to keep it as original as possible. I know there are a lot of little improvements that can be done but keeping something as a time capsule of how the bike rolled off the assembly line appeals to me. The bike isn't perfect, it's not a show-quality restoration but that's not my thing. The original patina is cool.

[N.DiGio]

Do you guys ever pack the bearings with grease whenever they are off?

[TOOLS1]

Always.
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[N.DiGio]

Well, obviously lol I guess what I should have asked is what type of grease?

[TOOLS1]

Hi temp wheel bearing grease.
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[N.DiGio]

Perfect, thanks!