Topic: Engine Bearing Replacement

[PeWe]

My understanding is that none of the bearings are different unless you have a CB750A (Hondamatic automatic transmission) which I think has an extra bearing. Don't quote me on that last bit though.

I know from Hondaman's book that at least the final drive bearing was different between models, although I think his book also states that they're interchangeable..

See service Bulletine from Honda
Russ Collins used a double row bearing in their Cobra build.

PeWe, where are you getting the copies of the service bulletins? I thought that they were available on sohc4.net but I think the links were bad last time I checked...?

I found them on this forum and saved them in my computer. They seems to be removed.

I MERGED MOST OF THEM INTO ONE PDF, see the file below, +7.6MB "Honda CB750 Service Bulletins.pdf"

https://sohc4-forum-attachments.s3.amazonaws.com/honda_cb750_service_bulletins.pdf

[PeWe]

More info attached below... Download my previous attachment while available...you'll never know..

[HondaMan]

Mark, I believe it's bearing #23 6304NR that is the HS (extra clearance) one.  You specify this in your book, and I also noticed the part description on bikebandit shows HS for this bearing.

I believe the correct list should be:

2 x HK2520 Needle Rollers
1 x 3206ATN9 Roller Bearing
1 x 6003 Roller Bearing
1 x 6008NR Roller Bearing
1 x 6204 Roller Bearing
1 x 6205 Roller Bearing
1 x 6205NR Roller Bearing
1 x 6304 Roller Bearing
1 x 6304NR/C3 Roller Bearing


I don't mean to point out mistakes, I just want to make sure others who search for this get the correct information.

You're right, Kickstart: it is the one by 5th gear, away from the clutch side. I'll go fix that!

[HondaMan]

More info attached below... Download my previous attachment while available...you'll never know..

I remember especially the Service Bulletin about the front axle clamps: when I apprenticed in Honda shops circa 1960s, the axle clamps came 2 ways. One way was with no markings, and those on the CB750 came with the gaps in the front, out of Honda's crates. The others have a little "F" cast on one end of each cap to show which way goes forward. Those came out of their crates with the gap at the back. Over the years, this has created lots of confusion: if you get them backward, the forks can bind against small bumps, making them feel locked.

Something to keep in mind if you flip the forks around to install the calipers on the back side of the legs (a once- popular 'custom' thing to do): flip the fork caps accordingly.

[Justin]

I'm fairly certain my K1 has the narrower 6305 bearing where many have the double row bearing pictured. Is it of any value for me to buy the double row bearing or should I simply replace like with like and get a new 6305?

[MessnerMoto]

Is there a company (SKF ,NTN....) Producing NR bearings with 2mm groove. If that is the case does 2mm groove bearings have spacial markings?

If nobody is selling 2mm groove NR bearings(I am not talking about OEM bearings) can I just widen the grooves on standard NR bearings...  I think grooves on standard NR bearings are 1.3-1.6mm

[edwardmorris]

Is there a company (SKF ,NTN....) Producing NR bearings with 2mm groove. If that is the case does 2mm groove bearings have spacial markings?

If nobody is selling 2mm groove NR bearings(I am not talking about OEM bearings) can I just widen the grooves on standard NR bearings...  I think grooves on standard NR bearings are 1.3-1.6mm

I replaced all mine with SKFs. Only the two small bearings on the primary shaft need their grooves widened. The large bearing between the clutch basket and the primary drive already has a 2mm groove on the NR replacement. To answer your question, at least I couldn't find any direct replacement other than OE or Yamiya. From what I've read, SKFs are the way to go, but pricey. Well worth it as you'll never need to change them again.

[edwardmorris]

From my K2 build

http://forums.sohc4.net/index.php/topic,126735.msg1506804.html#msg1506804