Topic: My CB750K2

[willbird]

Runs better "as it has been since 1992". Not exactly perfect but the best I have found so far. Runs really good at the throttle opening to cruise 50mph or more which is where it spends most of it's happy time :-).

Bill

[PeWe]

I have also fiddled with stock carbs lately.
I assembled a set of K6 carbs in parts.

Put them on my K2 that had a set of K6 carbs that started to behave badly, probaby dirty in need ultrasonic bath.
They were good on my 836cc K6 in the 80's

I carefully set floats to 26mm.
Float levels when checking with clear tube lower than I thought, 5mm from bowl gasket or even a few mm lower.

I had fuel starve after 120kmh.
I noticed that carb 1, 2 flowed badly.

So when checking float level and done, bend tube down into a canister and drain the bowl. See how much it will continue to flow.

My 1-2 carbs flowed really bad.
Floats were bent in such way so they probably bottomed out to bowl, float valve not opened enough.

Fixed by bending the floats upwards.

I hope they flow fuel enough for full speed.
3-4 flows better.
I have swapped fuel hose connections on dual tube  petcock that I also replaced just for sure.

[70CB750]

Great project, following. 

[HondaMan]

All this talk about floats in the K2 reminds me of something...
When the #657A carbs were ending (early 750K2 era) they were getting the plastic floats in these "A" bodies, and sometimes the 'new' #657B carbs would get brass floats (leftovers?). During this period (early K2) the float-valve-tab on the floats was rotated a little bit, which caused a wide angle between the face of the float-valve-tab and the pin of the float valve. This could make them stick open, unable to close the valve, until someone would sharply rap the offending float bowl (hard to do when it was #2 or #3) and then the valve would close.

To fix this, I'd bend the float's tab downward to a slightly steeper slope, then put a bend into the tab to angle it upward so as to be horizontal when it was supposed to be closed. This moves the tip of the float valve toward the end of the tab, but not so far that it falls off and gets stuck. This turns out to be more reliable and makes the fuel level more consistent.

In the later #657B carbs, somewhere after 1/1972 production, this problem went away.

[willbird]

Ordered a set of 4:1 rims and spokes, black rims.

Need to make or buy a stand to true the wheels.

Planning on shaving the ribs off the hubs in the lathe then maybe painting them with an eastwood single stage paint like this maybe.

https://www.eastwood.com/eastwood-dead-rat-black-single-stage-urethane-quart-kit.html

I have a K3 that I traded into way back in 1990 that I never got around to getting a title for so I can rob the wheelset from it, rebuild those, then swap them onto the K2 is the plan anyway.

Bill

[willbird]

Made a tool last weekend to unscrew the front hub bearing retainer, had some 12L14 handy so used it. The 1/8" endmill rubbed a bit but it still worked. Roughed it with a 3/16": endmill then finished with 1/8"

[newday777]

Nice job on making the bearing retainer tool Bill. I do wish I had stuck with learning the metal working now....
Post that in the Cool Tools topic that was started a year ago in the Open Topic section.

http://forums.sohc4.net/index.php/topic,191752.0.html

[Stev-o]

Cool tool!

[willbird]

Working up a cross section of the front hub. I know folks have turned off the decorative ribs in the center section and said "plenty of stock there" but I am a trust but verify kinda guy :-) so I wanted to draw it up in cad and have a look.



ordered up a set of these from Amazon to get up inside and measure wall thickness.



I also want to work the rim offset into this drawing. I checked it before cutting the spokes and got a .170" offset which is quite close to a 4mm number I have seen mentioned before. The brake disk flange side of the rim was .170" lower. I was able to set the wheel/rim on my granite surface plate and use a .500 gage block on the rim edge in order to measure. Bicycle wheel/rims the spokes IMHO are a lot more stretchey so the rim can be shifted side to side far more easily than a motorcycle rim can. It may not even be possible to get the rim in the wrong place on a MC wheel for all I know :-).

Bill

[BenelliSEI]

Nice work!

[willbird]

Calipers that some use to turn wooden bowls on wood lathe showed up. These allow measuring a wall thickness way down inside something like this. The answer was .266" at thinnest point so indeed "plenty" IMHO to turn the decorative ribs off for a more clean look. if we had a go at making a billet hub it would be difficult to duplicate the OEM shape internally in a machined from solid part and our part might end up a decent amount heavier than OEM.



4:1 rims and spokes showed up, look nice, inventory of all parts is complete. 4:1 makes a statement about these spokes being .2mm larger than OEM. Measuring shows that they are referring to the thinner portion of the spoke, the butted portion that goes through the holes in the hub is same exact dia as OEM.

Picked up another hub from Ebay, I needed brake rotor bolts and that one included them, so I will have two that I can machine and paint all in one go. Urethane single stage paint is kind of expensive and there is some waste so the more that I can paint in one adventure the less total waste :-).

Got a really nice rear brake assembly from Ebay too, looks like one a few years old would have looked, must have enjoyed a sheltered life :-).

I have a K3 that I treated like a parts bike and some parts wandered away during a move 20 years ago, have not yet found the rear brake assembly, if I can dig it out I will refinish it in the same batch with everything else. I had the sprocket side but have not yet laid hands on the brake side from that bike.

Bill

[willbird]

Found a really nice Vetter Vindicator fairing with lowers that was 2.5 hour drive away, snagged it. I don't think it ever slept a night outside. It is not perfect but overall wayy nicer than my Windjammer is, I'll archive the windjammer for now. . Pictures will follow once I get it hung on the bike. Had a Vetter radio box which features an 8 track player. I removed that :-).

[Stev-o]

Had a Vetter radio box which features an 8 track player. I removed that 

May have added a bit of nostalgia!  [My first car had an 8 track]

[willbird]

Had a Vetter radio box which features an 8 track player. I removed that 

May have added a bit of nostalgia!  [My first car had an 8 track]

As a kid growing up we had a radio shack deck that took three 8 tracks so I spent plenty of time listening to them, but never had one in a vehicle :-). Buddy had the full tilt radio shack setup to record 8 track tapes.

[BenelliSEI]

Had a Vetter radio box which features an 8 track player. I removed that 

May have added a bit of nostalgia!  [My first car had an 8 track]

Somewhere I still have a “Lear Jet” tape deck that my best friend’s Mom had installed in her E Type Jag, in Florida, in 1970. First one I ever saw!

[HondaMan]

Had a Vetter radio box which features an 8 track player. I removed that 

May have added a bit of nostalgia!  [My first car had an 8 track]

Somewhere I still have a “Lear Jet” tape deck that my best friend’s Mom had installed in her E Type Jag, in Florida, in 1970. First one I ever saw!

I remember those! They were a real status symbol in the Chicago area in those days.

[BenelliSEI]

Had a Vetter radio box which features an 8 track player. I removed that 

May have added a bit of nostalgia!  [My first car had an 8 track]

Somewhere I still have a “Lear Jet” tape deck that my best friend’s Mom had installed in her E Type Jag, in Florida, in 1970. First one I ever saw!

I remember those! They were a real status symbol in the Chicago area in those days.

Wow! Now I’ll have to try and find it! That same winter she brought home the first micro wave oven any of us had ever seen: “Amana Radar Range”. Her three sons and I spent a few days blowing up hot dogs!

[willbird]

I tend to work in circles LOL, had some stuff I was waiting on to get back to this project, one was a spare hub I bought on Ebay in order to get all the other hardware, the guy finally shipped it after about 4 weeks. Lesson re learned about reading seller feedback LOL.

So one of these is for the K2 and the other will be for the K3 getaway bike.







One is less perfect than the other because the worker back in 1972 got a little more crazy hand grinding the casting parting line. I did some caliper work prior to lathe work and made sure there is plenty of meat there to do this mod with no fear. These will get vapor blasted. I had planned on painting them but since found a local guy doing vapor blasting.

[willbird]

The Modulus of elasticity  of aluminum is way lower than steel so technically Aluminum is not the best choice for an arbor, or a boring bar. We learned that at a past job the hard way after making a boring bar out of Aluminum to make it lighter to hand load into the CNC, it did not work well. Sure looked pretty tho LOL. But this task the Aluminum is fine, the work is purely decorative.

[willbird]

Made two more tools to remove bearing nuts, got another batch of stuff ready for vapor blast. The tappet covers are from the K3 getaway bike.

[HondaMan]

Had a Vetter radio box which features an 8 track player. I removed that 

May have added a bit of nostalgia!  [My first car had an 8 track]

Somewhere I still have a “Lear Jet” tape deck that my best friend’s Mom had installed in her E Type Jag, in Florida, in 1970. First one I ever saw!

I remember those! They were a real status symbol in the Chicago area in those days.

Wow! Now I’ll have to try and find it! That same winter she brought home the first micro wave oven any of us had ever seen: “Amana Radar Range”. Her three sons and I spent a few days blowing up hot dogs!

Yeah...I blew up 2 eggs in one of those!
Boy, was she mad...

[HondaMan]

Made two more tools to remove bearing nuts, got another batch of stuff ready for vapor blast. The tappet covers are from the K3 getaway bike.

Nice homemade tooling: Your CNC is making me (and my little lathe) very jealous...

[willbird]

Made two more tools to remove bearing nuts, got another batch of stuff ready for vapor blast. The tappet covers are from the K3 getaway bike.

Nice homemade tooling: Your CNC is making me (and my little lathe) very jealous...

No CNC on my Bridgeport or Lathe....:-).

Bill

[willbird]

Stuff is back from vapor blasting, looks nice IMHO :-), the tappet covers are for the K3 getaway bike, wanted to give him some to practice on.


I wet sanded the brake backing plate with 600. I will take the one that is on my K2 and do it once I get these wheels built and on there, it is a learning process of judging what something looks like raw to guess what it will look like vapor blasted. A lot of this stuff really does not show but that backing plate does quite a bit depending on which exhaust you choose.

[HondaMan]

Nice homemade tooling: Your CNC is making me (and my little lathe) very jealous...

No CNC on my Bridgeport or Lathe....:-).

Bill

Bridgeport!
Now you're makin' me MORE jealous...
Geeezzz...