Topic: 1971 CB750 K1 Restoration Project- Restoring Still...

[denward17]

I ordered a set of these last year, really like them.  They are easier to use through the 750/550 valve adjustment holes.

https://www.amazon.com/dp/B008BYQ0R4?psc=1&ref=ppx_pop_dt_b_product_details

[Oly]

Ready for install into the frame...

[BenelliSEI]

Well done! That looks great.

[Stev-o]

Well done! That looks great.

+1.......

[Oly]

As I wait for my son to help load the engine into it's frame, I started looking into my clutch components in an attempt to determine if I had all the correct ones for my engine VIN ( CB750E-1050393).  The forum discussion related to early clutches or clutches in general, has a lot of variation even when looking at the Honda Parts List on page C12 for K0, K1 & K2 bikes.

Attached is a picture of the clutch assembly with all the parts I removed. 

I in the stack-up of steel plates (Ref #6) I have Qty. 6.  For the friction plates (Ref #4) I have Qty. 7 and P/L says I should have Qty. 6. and the last in that stack-up I have a Clutch Outer Ring (Ref. #3) I have Qty. 1.
When I assemble the stack-up with only 6 friction plates it looks to be 1 friction plate short, but with 7 plates it looks complete. (ref. attached).  I'm feeling like 7 friction plates is the right answer, but then I'm not sure how the Clutch Outer Ring (#3) fits into the stack and it's orientation.

Any feedback would be greatly appreciated...

[Kevin D]

Mine is an 11/71 K1 (e-1068xxx) with 7 corks 6 steels.

[Oly]

Mine is an 11/71 K1 (e-1068xxx) with 7 corks 6 steels.

Thanks Kevin... The change over from 6 corks to 7 is at vin# e-1056080 and up.  Does yours have a Clutch Outer Ring (#3 on P/L) and if so what is it's orientation when placed into the clutch  assembly?

[Kevin D]

Mine is an 11/71 K1 (e-1068xxx) with 7 corks 6 steels.

Thanks Kevin... The change over from 6 corks to 7 is at vin# e-1056080 and up.  Does yours have a Clutch Outer Ring (#3 on P/L) and if so what is it's orientation when placed into the clutch  assembly?

No, Oly, I don’t have the outer ring, never did.

[Oly]

Mine is an 11/71 K1 (e-1068xxx) with 7 corks 6 steels.

Thanks Kevin... The change over from 6 corks to 7 is at vin# e-1056080 and up.  Does yours have a Clutch Outer Ring (#3 on P/L) and if so what is it's orientation when placed into the clutch  assembly?

No, Oly, I don’t have the outer ring, never did.

Thanks again Kevin. 
I'll entertain leaving the Clutch Outer Ring off if I don't get any other leads on what it's purpose is and how it is placed into the assembly.

Kevin did you by chance modify your Clutch Center (Ref.#2 on P/L) as described in Hondaman's book by adding additional holes for increased oil distribution?

[Kevin D]

Mine is an 11/71 K1 (e-1068xxx) with 7 corks 6 steels.

Thanks Kevin... The change over from 6 corks to 7 is at vin# e-1056080 and up.  Does yours have a Clutch Outer Ring (#3 on P/L) and if so what is it's orientation when placed into the clutch  assembly?

No, Oly, I don’t have the outer ring, never did.

Thanks again Kevin. 
I'll entertain leaving the Clutch Outer Ring off if I don't get any other leads on what it's purpose is and how it is placed into the assembly.

Kevin did you by chance modify your Clutch Center (Ref.#2 on P/L) as described in Hondaman's book by adding additional holes for increased oil distribution?

Yes, I have done the Hondaman mod, I have also replaced the fibers and have heavy springs.
106000 miles on my bike now, the clutch is performing very well. But I’m not a ton runner or a drag racer.
And Fortunately I’m still using the original clutch lifter plate.

[BenelliSEI]

If anyone needs a lifter plate I found two NOS in the stuff I bought from Flybackwards.

[Oly]

I'm good John...thanks for thinking of me.
 I got a new Honda part from South Sound Honda already.

[Oly]

Kevin... Does your outer clutch hub fingers have the reinforcing band around the outside?

[Kevin D]

Kevin... Does your outer clutch hub fingers have the reinforcing band around the outside?

Oly, I can’t tell you for sure, but I believe that it does.

[Oly]

Kevin... Does your outer clutch hub fingers have the reinforcing band around the outside?

Oly, I can’t tell you for sure, but I believe that it does.

Thank you Kevin.  I'm just trying to get my head around the clutch configuration mine came with and if I'll assemble it the way I found it.

[Oly]

If anyone that has a K1 with an engine VIN # prior to cb750e-1056080 and is running 7 cork plates & 6 steel plates in their clutch stack-up with a Clutch Outer Ring incorporated and the Outer Clutch Hub DOESN'T have a reinforcing band around the outside, I would love to hear from you on how that configuration is working for you.

Any input would be greatly appreciated.

[MauiK3]

I think I'd just go with what the manual says.

[PeWe]

Hondaman has explained clutch differences before.
http://forums.sohc4.net/index.php?topic=64339.0

Maybe more here
http://forums.sohc4.net/index.php?topic=7401.0

Also important to check which parts you have. The outer ring must fit a specific clutch basket or the other parts?
Visit CMSNL and their part fiches for K0,,K1, K2....

There is a risk you have got mixed parts for different models.

K1 clutch

https://www.cmsnl.com/honda-cb750k1-four-1970-1971-usa_model14354/partslist/E09.html




Check which parts you need.

Ring and "steel basket" differ.
Early model with ring, later not which has different steel basket. Look like K2.

[Oly]

Hondaman has explained clutch differences before.
http://forums.sohc4.net/index.php?topic=64339.0

Maybe more here
http://forums.sohc4.net/index.php?topic=7401.0

Also important to check which parts you have. The outer ring must fit a specific clutch basket or the other parts?
Visit CMSNL and their part fiches for K0,,K1, K2....

There is a risk you have got mixed parts for different models.

K1 clutch

https://www.cmsnl.com/honda-cb750k1-four-1970-1971-usa_model14354/partslist/E09.html




Check which parts you need.

Ring and "steel basket" differ.
Early model with ring, later not which has different steel basket. Look like K2.

Thanks Maui and Per...
  I do have the K1 early style clutch with the "Steel Basket" Hub and Clutch Outer Ring w/ 7 Corks & 6 Steels so that's how I'll reassemble it, as it is the configuration that I saw at disassembly.  I just had a lot of questions to get to that conclusion because of there being so many configurations documented as the clutch assembly changed from K0-K3.

I have clutch springs that are considerably longer than what is documented.  My Shop Manual & Hondaman's book states they should have a length of 1.258 inches, but mine are between 1.46 and 1.47 inches.  They worked fine at last usage so I'll just use them again.

[BenelliSEI]

It’S been ages since I replaced the cork plates in my K1, but I do remember it was different than what I found in a few manuals. Like you, I just put it back the way it came apart and it’s been working just fine! Good plan.

[Oly]

I'm in the process of replacing my swing arm zerk grease fittings with ones that my grease gun will positively attach to and I see discussions in the past that some have used 13/64" (0.2031) diameter drill bits for taping a 1/4-28 threaded hole, but the tap drill charts I see are calling for a #3 drill bit (0.2130) to be used for that tap size.
 Has everyone tapping for 1/4-28 threaded holes successfully used a 13/64" bit instead of the #3 bit?

Any input is greatly appreciated.

[Oly]

I'm in the process of replacing my swing arm zerk grease fittings with ones that my grease gun will positively attach to and I see discussions in the past that some have used 13/64" (0.2031) diameter drill bits for taping a 1/4-28 threaded hole, but the tap drill charts I see are calling for a #3 drill bit (0.2130) to be used for that tap size.
 Has everyone tapping for 1/4-28 threaded holes successfully used a 13/64" bit instead of the #3 bit?

Any input is greatly appreciated.

Well, with as many people here saying they have done this update I thought this (possibly) dumb question would be easily answered or someone would say get off your butt and buy a #3 drill bit... LOL   I guess that's what I'll do, as I don't want to risk using the bits I have on hand if they could possibly jeopardize messing up the only swing arm shaft I have.

[seanbarney41]

drill a test hole, try to tap it...if the rap turns too hard the hole needs to be bigger, if there is not enough metal left to form decent threads it's too big.

Zerks are not holding up a bridge.  They just have to snug up good and tight

[scottly]

13/64" is for 1/4-20 coarse thread, not 1/4-28 fine thread.

[Oly]

Did a couple test holes with the drill bits on-hand, but they were not going to cut it for the 1/4-28 tap, so I ran down the correct bit (#3 wire gauge drill bit 0.2130 dia) for the 1/4-28 tap at the local ACE Hardware. 
Setup the shaft in the vice, drilled holes, blew out chips with air, ran the tap thru & blew out again. 
Finished up by pushing grease thru new fittings.  The right tools always make the job easy (you'd think I'd have learn that by now....just too Froogle (cheap) I guess...lol