Topic: Phaedrus: CB750 RestoMod - Update: 09/23/21 w/ new video

[HondaMan]

Is it true that some of our most vulnerable CB750 gears are no longer available from Honda?

Service Honda shows the C5 gear (that's the jumps-out-of-2nd gear) as not available for the "K" bikes. I have a very worn one that I'm experimenting with to see if the dogs can be cut back (i.e., the rounded portions squared back up) to recover them. While this won't work with high-output engines, as it makes the dogs smaller, it could work fine with normal engines and use. Back-cutting it and C2 next to it could prevent future reoccurrence, too.

Another Hondaman part, maybe?

[Joksa]

While this won't work with high-output engines, as it makes the dogs smaller, it could work fine with normal engines and use.

Does it affect the strenght of the part so much if you shorten the dogs? Isn't the gears shimmed closer at the same time?

[traveler]

How feasible is it to have a new gear cut from billet chromoly steel?

If you were to do a bunch with a group buy in, it seems like it could be handled...same with the forks always wearing out.

At some point, it will have to be done, as parts are dwindling down.

~Joe

[MCRider]

Is it true that some of our most vulnerable CB750 gears are no longer available from Honda?

Service Honda shows the C5 gear (that's the jumps-out-of-2nd gear) as not available for the "K" bikes. I have a very worn one that I'm experimenting with to see if the dogs can be cut back (i.e., the rounded portions squared back up) to recover them. While this won't work with high-output engines, as it makes the dogs smaller, it could work fine with normal engines and use. Back-cutting it and C2 next to it could prevent future reoccurrence, too.

Another Hondaman part, maybe?

That's what I thought. When I repaired mine many years ago, I know I bot brand new parts. Now we're looking at reconditioning old parts.  

Undercutting may be a good fix. Seems its only a matter of a few thou taper that can make them jump out and a few thou reverse taper may fix it. I wonder about the shift fork as they need attention often as well.

My Phaedrus II tranny is from a low mileage bike and has been undercut, and cryo treated. Hopefully thats good for my lifetime.

The next project I'll need to look for some parts.

The bike in my avatar was breathed on heavily by Dick Suarez in Ft Lauderdale who worked for Yoshimura for a while in 69-71. I know this as we met Pops in Daytona in 71 and they shook hands like old friends. Nice to know he wasn't snowing me. Any way...

He put a diferent shim in my tranny, he was all giddy about it saying it was the hot trick. I was too young, 19, to realize i should have been paying attention. I think it moved the gear in question a few thou closer to its mate and secured the 1-2 shift a little better.  Maybe there is something to that. Or I may have been dreaming.

Could the dogs be welded up and ground down like a cam? Maybe the shift fork too?

[Joksa]

He put a diferent shim in my tranny, he was all giddy about it saying it was the hot trick. I was too young, 19, to realize i should have been paying attention. I think it moved the gear in question a few thou closer to its mate and secured the 1-2 shift a little better.  Maybe there is something to that. Or I may have been dreaming.

AFAIK the trick is to replace shim with two half-width shims (another on the other side of the gear). I cannot recall which Honda model the shims were from.

[MCRider]

He put a diferent shim in my tranny, he was all giddy about it saying it was the hot trick. I was too young, 19, to realize i should have been paying attention. I think it moved the gear in question a few thou closer to its mate and secured the 1-2 shift a little better.  Maybe there is something to that. Or I may have been dreaming.

AFAIK the trick is to replace shim with two half-width shims (another on the other side of the gear). I cannot recall which Honda model the shims were from.

Ah that makes sense. I'd bet its from a CB350. Just a WAG

[HondaMan]

He put a diferent shim in my tranny, he was all giddy about it saying it was the hot trick. I was too young, 19, to realize i should have been paying attention. I think it moved the gear in question a few thou closer to its mate and secured the 1-2 shift a little better.  Maybe there is something to that. Or I may have been dreaming.

AFAIK the trick is to replace shim with two half-width shims (another on the other side of the gear). I cannot recall which Honda model the shims were from.

Ah that makes sense. I'd bet its from a CB350. Just a WAG

It was from the early CB350: it was the shims Honda added between the 2-3 gears when they changed those from the 1968-69 version (no spacers) to thinner gear shoulders with a thin thrust washer between, in a retrofit kit (when hot and the clutch pulled in, the gears would drag so much the rider could not shift into neutral unless the bike was rolling). They redesigned the tranny on those bikes in the 1970 version to fix that, and to include several other changes, like a larger (19mm from 16mm) oil pump and earlier cam opening profile. The changed parts cost the engine about 1.5 HP at the top end and lowered the redline from 10500 to 9200. I remember it well!

The washer in question (from that retrofit kit) was real thin, but what you're saying makes perfect sense. As soon as I finish Andy750's swingarm today, I'm gonna go look at the 3 trannys I have apart (left from the book stuff) and figure that out. It's a great idea: the shoulders of the gears and their thrust washers do wear over time, and narrowing the gap will engage the dogs more deeply - always desired...

I discussed the "weld up and re-machine" approach with some local machinists for a 750F I'm fixing now (C5 dogs worn): the consensus is that the iron won't weld up well, but will melt away instead. So, I took a small grinder to the dogs to cut them back to the point where the roundness is removed and they are square again: this would work if the engine was not high-output (it's a 10:1 CR 836cc engine, though...). I'll save that gear for a future repair. I still have to gage it to make sure they are 120 degrees apart, to match the C2 gear slots, and adjust accordingly... 

[wannabridin]

so Mark,

a rough square grind would work for a more or less stock motor you think?  MReick might have convinced me to go 836, but once i inspect my transmission, i want to make sure i'll have a good lasting gear with smooth, strong shifts...

[bucky katt]

bolt the bulldog to the gas cap! like a Billy Lane gastank 

[Terry in Australia]

bolt the bulldog to the gas cap! like a Billy Lane gastank 

Is Billy Lane out of jail yet fuzzy?

[MCRider]

Here we go. My project buddy had to do V Day duties (I got mine done Sat night) so i was working alone. Hadn't done that in a while. Finally finished polishing the hub. had to say, OK 1 hour. Whatever it looks like at the end is what I'll go with. 15 min for each rouge (3) and 15 min for changing wheels and cleaning etc. Result:




Done. Looks better in the pictures than in life, but ...done.

Got a lot of polish gunk in the spoke holes. Cleaned them with a tube brush in the drill.



So it turns out the hub I sold to Terry is the one I should have kept, and the one I kept is the one he needs.  So swap time. That'll delay the front wheel a bit longer...and I'll get to polish another hub. So no lacing.

Started cleaning up electrical parts. I have a new loom, so that's done. But the components are all used, a couple of drops of this in each.

So using a brush from my cleaning kit for my .22cal rifle works real well for the round females.

My old plastic point file works great for flat connections and the headlight connector.


I started to strip the wires off the left hand switch. The covering was so brittle it would SNAP instead of bend. I thought great, I'l just cut it off and at the same time remove the button and 2 wires that cancels the signal beeper, which i won't use. About 1 or 2 snips from the end, I hooked the blue turn signal wire and cut it through . DAMN.

Cut it to the quick, irreparable. Oh well, the switch housing was pretty washed out. I have a new K0/1 style for the right. I'll go to Yamiya and get a K0/1 style for the left. One thing i can do is spend money.

Did some other futzin around, bot some chrome allen heads for the switch gear, cleaned up the rectifier and regulator from 30 years of grime.

Next week, hope to make good headway on the electrics, maybe oil up the forks.

[MCRider]

Woo Hoo, less than 100 away from 40,000 hits!  

PS: Ding ding ding we hit it. 40,000+ hits and 1000+ replies is more than any project thread going back 20 pages. Kinda cool. But... what's in a number, nothing special really.

What is special is that I started this thread to try and inject some discipline and accountabiity into my process. Without the incentive to post a weekly update, and without my co-builder showing up every Sunday morning, I don't think I'd be this far along. I may have stalled out again like I did back in 2000.

We've really covered a lot of topics: fixing cracked plastic, discussing brake efficiencies and cross drilling, measuring primary chains, powdercoating, wheel building, frame gusseting, valve spring setup, swingarm setup, odd and exotic parts, its been fun.

Now I hope it will come to finish before the next 40,000 hits. Thanks everyone for keeping me on track and focused and thanks to the site for providing the forum.

[wannabridin]

congrats!!  i sure hope my build thread has 1/4 as many hits and replies as you!!!

[mystic_1]

Psst Ron, click the Views column header to sort by number of views, descending.

You're currently #3, only behind "A Noob's 75 CB550 Cafe Project Thread" and "INSPIRATION GALLERY" 


Sorting by number of replies, you're #2

mystic_1

[MCRider]

Psst Ron, click the Views column header to sort by number of views, descending.

You're currently #3, only behind "A Noob's 75 CB550 Cafe Project Thread" and "INSPIRATION GALLERY" 


Sorting by number of replies, you're #2

mystic_1

I did qualify it by saying in the last 20 pages. I clicked back thru 20 pages (I didn't know about the clicking the header trick) and that got me back to the middle of 2008. The Noob's thread stopped in 2007. But quite a nice bike.

Anyway, guess I'll have to string mine out a little longer. 

But the main thing has been the interaction, which I never expected when i started out.

[HavocTurbo]

I think everyone is stunned by the level of detail and forethought you are using.

I know I am.

I've usually just put bikes together with a theme goal in mind. Never did it occur to me to redo every little thing on a bike until now.

Which has started me on wiping the slate clean and starting with a whole new and fresh idea.

That and a constant weekly reminder of how angry I'm sure my bike is for not being worked on..... That could help a little. 

[MCRider]

I think everyone is stunned by the level of detail and forethought you are using.

I know I am.

I've usually just put bikes together with a theme goal in mind. Never did it occur to me to redo every little thing on a bike until now.

Which has started me on wiping the slate clean and starting with a whole new and fresh idea.

That and a constant weekly reminder of how angry I'm sure my bike is for not being worked on..... That could help a little. 

Thanks. Well, I've done many build ups with a lot less detail. And there's nothing wrong with that. This is a special project for a special time in my life when I can do it. I have a little extra money, my first real shop area, and other things to ride.  And timing helps. I wouldn't have done as well without the forum and places like Yamiya which weren't around 10 years ago, I think.

[HavocTurbo]

Well you can include me among the admirers of your handy work.

While my bike will take a different look than yours.... I hope to attack it with the level of discipline and detail that you have. At least to the best of my ability anyway.

I ordered that flasher..... backordered.  So when it gets here I'll shoot it off to you asap!

[HondaMan]

I started to strip the wires off the left hand switch. The covering was so brittle it would SNAP instead of bend. I thought great, I'l just cut it off and at the same time remove the button and 2 wires that cancels the signal beeper, which i won't use. About 1 or 2 snips from the end, I hooked the blue turn signal wire and cut it through . DAMN.

Cut it to the quick, irreparable. Oh well, the switch housing was pretty washed out. I have a new K0/1 style for the right. I'll go to Yamiya and get a K0/1 style for the left. One thing i can do is spend money.

Send me your old switch and postage for the return, and I'll repair that like new for ya. 
Send the snipped wire, too.

[MCRider]

HM:  I've bot a new one. I have no need for the old one now. Can you use it? Freebies. Don't want to load you up with my discards if you really can't use it, sell it or whatever.
Ron

[HondaMan]

Actually, I could use it: my K2 switch contacts on that side are so worn that I have to hold the switch over to make the turn signals flash. The switch is OK: the detents are worn out from 130k+ miles!
 
I'd gladly cover the postage, at least! I need that turn signal killer because I can't stand that thing in town, but it helps me on the busy freeways around here (especially when my Partzheimer's acts up. It's not all the time, just part of the time...) 

[wannabridin]

mark,

what all do you do to freshen up the switch housings?  i've tried to get mine in better shape, but no such luck!!

[HondaMan]

mark,

what all do you do to freshen up the switch housings?  i've tried to get mine in better shape, but no such luck!!

(Did you order a book already? I don't want to sound facetious with this next comment...). Go to page V-24. The whole process is there! 

[wannabridin]

PERFECT!!!  I sure did Mark, it's Garrett, we talked yesterday thru e-mail.  Thanks again for all the help!  i can't wait to get the book!!!  hurry up post office!!!

[MCRider]

Actually, I could use it: my K2 switch contacts on that side are so worn that I have to hold the switch over to make the turn signals flash. The switch is OK: the detents are worn out from 130k+ miles!
 
I'd gladly cover the postage, at least! I need that turn signal killer because I can't stand that thing in town, but it helps me on the busy freeways around here (especially when my Partzheimer's acts up. It's not all the time, just part of the time...) 

Well, ... I'm putting together a care package for you. Stuff I'll never use and sounds like you could.