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

[Ecosse]

Even though you start with 5psi, when the forks compress to near bottoming the psi goes through the roof.  Evidently.   

I have the faint impression you speak from experience.

Yours is high on my list of anticipated build completions.

[Terry in Australia]

Nice work Ron, I like Rob's engine mount too, but I'm going to make a pair of "plates" that tie the two rear mounts and the swingarm pivot together, like the ones Patrick Bodden used when he built "Big Benly", his CB750 based race bike.

I've seen a similar set-up on Rex Wolfendon's race bikes, but he cunningly welded in unobtrusive steel plates around the same area and then painted/powdercoated his race frames so that the bracing was less obvious. This mod is supposed to improve the handling more than just about any other form of bracing, and (although I've never had the opportunity to ride either bike) according to reports written about them in various bike magazines, these bikes apparently handle like no other CB750's ever built. 

I love those air caps too, I've got a couple NOS sets in boxes that I bought on EBay years ago, including an S&W air kit that I bought for my Suzuki GS1000S. I had the same kit on my Kawasaki Z1 years ago, and discovered an interesting phenomenon, I would inflate them to 10 psi, and at around 60-70 mph the fork mounted air gauge would read ZERO psi, then once I slowed down to 35mph again, the reading would return to 10 psi. I theorized that at highway speeds the front of the bike would slightly "lift", which probably goes a long way to explain the instability that old Kawasaki Z's were (in) famous for..............

You can wheelie a CB750? You're a bloody legend mate, that's no mean feat! Cheers, Terry.  

[MCRider]

Nice work Ron, I like Rob's engine mount too, but I'm going to make a pair of "plates" that tie the two rear mounts and the swingarm pivot together, like the ones Patrick Bodden used when he built "Big Benly", his CB750 based race bike.

I've seen a similar set-up on Rex Wolfendon's race bikes, but he cunningly welded in unobtrusive steel plates around the same area and then painted/powdercoated his race frames so that the bracing was less obvious. This mod is supposed to improve the handling more than just about any other form of bracing, and (although I've never had the opportunity to ride either bike) according to reports written about them in various bike magazines, these bikes apparently handle like no other CB750's ever built. 

I love those air caps too, I've got a couple NOS sets in boxes that I bought on EBay years ago, including an S&W air kit that I bought for my Suzuki GS1000S. I had the same kit on my Kawasaki Z1 years ago, and discovered an interesting phenomenon, I would inflate them to 10 psi, and at around 60-70 mph the fork mounted air gauge would read ZERO psi, then once I slowed down to 35mph again, the reading would return to 10 psi. I theorized that at highway speeds the front of the bike would slightly "lift", which probably goes a long way to explain the instability that old Kawasaki Z's were (in) famous for..............

You can wheelie a CB750? You're a bloody legend mate, that's no mean feat! Cheers, Terry.  

yes I have that Big Benley article in my file. The plates are some work. I never could quite focus on what was done esp around the swingarm bolt. Is it a clamp affair that surrounds the swingarm nut?

Your observation about the pressure going to 0 is interesting and does explain things. i remember seeing a show about NASCAR where they taped a row of streamers on the car and took it out and the streamers would stand up or lay flat depending on speed and angles on the track. They got results that they weren't getting in the windtunnel.

Not sure where you picked up my claim of wheelie, a mis-read of something I wrote. While I've popped the wheel up many times I would hardly call it a proper wheelie and wouldn't lay claim to such.

Oh I see it now, I said "wheeling" not wheelying, meaning I was just idling around in the dirt parking lot. I dropped the front wheel into a deep rut made by an RV or something, causing a near bottoming of the fork and the explosion of my poorly engineered fork caps. Sorry for the misunderstanding.

[voxonda]

I have worked with the solution that Patrick Bodden used, which is a very old solution, in the '70 's these plates incorporated the rear sets also. But when working on the engines, between races, you also had to remove the pivot axle. I then did it "my way"(thanks Frankie) and there was no set back in rigidy or whatever and IMO it looks a bit "cleaner".
Cheers, Rob

[MCRider]

I have worked with the solution that Patrick Bodden used, which is a very old solution, in the '70 's these plates incorporated the rear sets also. But when working on the engines, between races, you also had to remove the pivot axle. I then did it "my way"(thanks Frankie) and there was no set back in rigidy or whatever and IMO it looks a bit "cleaner".
Cheers, Rob

I though going the plate route on this project may be too troublesome. I'm using stock footpegs and just not up to thinking it through. I'll never use the stiffness I'm going to have with the gussets i have, your motor mount, etc.

Still I like all the cool ideas, overkill or not.

Maybe my next project the rat cafe, I'll do something more substantial. On the other hand if your bracket is enough...

I'll never ride the rat hard enough to know the difference either.   

[voxonda]

I have worked with the solution that Patrick Bodden used, which is a very old solution, in the '70 's these plates incorporated the rear sets also. But when working on the engines, between races, you also had to remove the pivot axle. I then did it "my way"(thanks Frankie) and there was no set back in rigidy or whatever and IMO it looks a bit "cleaner".
Cheers, Rob

I though going the plate route on this project may be too troublesome. I'm using stock footpegs and just not up to thinking it through. I'll never use the stiffness I'm going to have with the gussets i have, your motor mount, etc.

Still I like all the cool ideas, overkill or not.

Maybe my next project the rat cafe, I'll do something more substantial. On the other hand if your bracket is enough...

I'll never ride the rat hard enough to know the difference either.   

Even when I am riding on closed circuits, I am not fast enough to use the bike to his full potential, but hey..... it is my baby and I do with her what I like  It is all part of our hobby, isn't it. Love it when people 'go their own way' if agree or not. Still hope you're happy with the mount which is good enough for 98% of us. That's a promiss.

Cheers, Rob

[MCRider]

That's right, its a hobby, fun for fun's sake, at least in this part of the country. When I was young in Tucson, I didn't own a car, just 3 bikes.

Anyway, very happy with the part. Eye candy. I have no skills like that of my own, so I like to show off others work.

I'm about 90% sure I'll have it chromed. Brown's said the chrome is 6 to 10 thou thick, so I'll take that off the frame.

[Terry in Australia]

Sorry Rob, I didn't infer that your engine mount is any way inferior mate, it looks fine, but obviously doesn't perform the same function as Boddens plates, as it doesn't tie the two rear mounts and the swingarm pivot together, it just strengthens the one mounting point.

Also, as you need a longer swingarm pivot bolt when using the plates, it's simple enough to make a new bolt, or perhaps, "stud", is more correct, threaded at both ends like your rear engine mounts, that way you only need to remove the two nuts to take the plates off in the pits, and not remove the swingarm pivot bolt itself.

I was going to use a spare F2 pivot bolt on my bike, (the F2 pivot bolt goes thru the F2's cast alloy footpeg brackets so is an inch or two longer than the K series pivot bolt) but after you raised that very relative point, I'll either cut the head off it and thread the other end, or make an entirely new stud instead.

Ron, the plates actually "clamp" onto the swingarm pivot bolt, as you suggest. I laughed when I thought about your misadventures with the air forks, I remember reading about one bloke in the US who actually removed both his fork springs "back in the day" only to have his forks explosively collapse after performing a wheelie, sending him over the handlebars with his face covered in fork oil. Apparently he'd read all about the famous Fournales air shocks that were made by the same company that provided shock absorbers to the company that built the Concorde airplane, he figured that if they didn't need springs, neither did his forks. He was wrong................

Have fun with that build mate, the weather here is still hot, (was 90 deg F at 5 pm yesterday) so I'm going to sneak off from work early today and install some new NGK D7EA plugs in my 836cc engine (it hated the NGK Iridiums that cost me $100.00 and ran like shiite) and drop the needles on the CR's a notch, and take it for a blast. Cheers, Terry.

[MCRider]

It was funny. At least I still had my springs in. Only one side, rubber wheel valve) popped out, but 200cc +/-  of oil sure makes a mess.  Sounds like your guy must have blown out the seals?

My second try, the fittings threaded into the fork nuts, is solid and foolproof.

When/if I get around to my "rat cafe",  I'll get more details on the plates. Heck I might do both! Plates and the double decker. And a Tony Foales style pyramid crossed brace. And anything else I can squeeze in there.    

Yup, D7EAs are what i always ran. Its funny what some people will deem necessary and others not. Oil, spark plugs, tires, easy to get a heated thread going on those topics. I could not bring myself to pay more than the minimum for plugs and just change them a little more often.

[voxonda]

Sorry Rob, I didn't infer that your engine mount is any way inferior mate, it looks fine, but obviously doesn't perform the same function as Boddens plates, as it doesn't tie the two rear mounts and the swingarm pivot together, it just strengthens the one mounting point.

Also, as you need a longer swingarm pivot bolt when using the plates, it's simple enough to make a new bolt, or perhaps, "stud", is more correct, threaded at both ends like your rear engine mounts, that way you only need to remove the two nuts to take the plates off in the pits, and not remove the swingarm pivot bolt itself.

I was going to use a spare F2 pivot bolt on my bike, (the F2 pivot bolt goes thru the F2's cast alloy footpeg brackets so is an inch or two longer than the K series pivot bolt) but after you raised that very relative point, I'll either cut the head off it and thread the other end, or make an entirely new stud instead.

Ron, the plates actually "clamp" onto the swingarm pivot bolt, as you suggest. I laughed when I thought about your misadventures with the air forks, I remember reading about one bloke in the US who actually removed both his fork springs "back in the day" only to have his forks explosively collapse after performing a wheelie, sending him over the handlebars with his face covered in fork oil. Apparently he'd read all about the famous Fournales air shocks that were made by the same company that provided shock absorbers to the company that built the Concorde airplane, he figured that if they didn't need springs, neither did his forks. He was wrong................

Have fun with that build mate, the weather here is still hot, (was 90 deg F at 5 pm yesterday) so I'm going to sneak off from work early today and install some new NGK D7EA plugs in my 836cc engine (it hated the NGK Iridiums that cost me $100.00 and ran like shiite) and drop the needles on the CR's a notch, and take it for a blast. Cheers, Terry.

Hey Terry, no offence taken here. Can understand your point. In the 'dark ages' when we raced the K-models there were no longer F2 bolts, simply because there weren't any. Had to do with what you had. I have gusseted my frame around the pivot area so the extra plates just add some weight and do very little to the strength in that area. Still love that "Big Benly" bike though. One of the nicest ones around IMO.

cheers mate, enjoy your ride today! It was still freezing here last night

[MCRider]

Nothing new to show. Lots done. Spring cleaning...just a tip. If you have a polishing station, maybe don't work right next to your toolbox. Mine is (was) covered in polish dust. Got most of it cleaned up. Worked some more on the welds, grinding and smoothing, packed up the swingarm to go to HondaMan's tomorrow. Packed up the frame for one more trip to machine shop, Saldana, Tuesday. Hopefully the last. But after it gets powdercoated, I won't get a second chance. I'll have Saldana make me the little shim Voxonda came up with to put a little more spring tension on the primary chain tensioner.

Sold some parts on eBay to build up my Paypal account. Placed an order with Yamiya for missing parts, petcock, taillight mount rubber, taillight assembly, chrome shoulder bolts, lock tabs. Some things I could get in states, but the taillight assembly I've only found at Yamiya, and ordering it creates the opportunity to buy everything else from them and consolidate the shipping. Undoubtedly I've forgotten something.

Next while waiting, I can install brake shoes, tune them to the drum. An old trick, possibly gross overkill, is to install the shoes, check them for contact patch on the drum, pull apart and sand down. Rinse and repeat until contact patch of shoe to drum is optimized. I've done this once before and to my SOTP, the brake seemed to be more progressive and effective. True or not, it is amazing how little of the new shoes actually touch the drum upon installation. I suppose over time wear may equalize this, but its what I want to do.

Front fork legs need to be assembled as well.

Step by step.

[Ecosse]

Gotta admire a man who attends to the details.

Hondaman will need sunglasses when working on your SA. 

[MCRider]

I knew I wasn't crazy. Doing some research on my forks at Race Tech, I ran across this: http://www.racetech.com/HTML_FILES/BrakeArcing.html

A rather negative, but enlighteing discussion: http://obsoleteskills.com/skills/arcingbrakeshoes

A more positve approach, emphasizing asbestos free linings. I don't know if my replacement linings are asbesots free or not.
http://model-a-wis.com/brakearc.pdf

and there are quite a few more links if you Google "brake shoe arcing" and the like.

The 750 rear brake has been dissed (and its not a disc after all) but much can be done to optimize it. The cons are it is sticky, fades fast, non-progressive, on or off, etc.

Holding the brake pedal down while tightening the axle does a lot by itself by centering the brake panel in the drum. If the shoe on one side is contacting 5 to 10 thou before the other side, well that's less than optimal.  And if only the 1 or 2 inches of the shoe begin touching hard before the rest of the shoe, well you've only got a 1 to 2 inch shoe. It will get hjot thre quickly and fade.

I have arced the shoes myself with a primitive hand file followed with emory paper. Does a lot to improve the grabby "on-off" feel, hot spots fading, etc.  Paying $200 + S&H to RaceTech would be cool, maybe someday.  But if my racer had drum brakes, it would be a necessity.

[MCRider]

Had a good session. Nothing new to show though. Got the swingarm into HondaMan's hands Friday via UPS. No hurry to get it back though as i gotta get the frame finished and PowderCoated.  Didn't get it to the machinists as I thought I would. Just no time away from work. So I drilled and tapped some things on the frame. Did a little more grinding and smoothing. Best for me to take that slow and step away when I get frustrated.

Got the dampers back in the rear hub. New seals on the already new and installed wheel bearings. New bearing retainers. Got the shoes reinstalled on the backing plate. Things like that. Almost finished making a universal bearing retainer pin spanner from a suggestion here. I'd already made a good one from wood and nails.

But better is simply a 24 inch piece of flatstock aluminum. Properly spaced holes near the center for the 3 or 4 different spacings of retainers, front and rear wheels. Then a pair of short 8/32 bolts, threaded into the proper holes, will remove any retainer.
Step by step.

[Ecosse]

i'm willing to give you my future BOTM vote now.

like mec's, yours looks fantastic even unfinished!

 

[MCRider]

i'm willing to give you my future BOTM vote now.

like mec's, yours looks fantastic even unfinished!

 

Thanks for your consistent encouragement, it really helps. I would be happy just getting nominated for BOTM, and I hope that's in 2009. It may be my BOML (bike of my life) While I'm in perfect health, my dad died at 51 in perfect health, at least so he thought, so at 56 I'm keen on doing what's been on my mind.

Not to be too morbid, I've got plenty more things to do.

Being mentioned with MEC is nice too. While his skill level trumps mine in so many ways, I'm doing the best I can. I used the Dremel tool with a cutoff blade for the first time today. 

The first confluence of parts will be the frame and the rear end. Hoping to gather all that together within the next several weeks and assemble. Then we can see the colors and the "theme" of the project more clearly.

[Ecosse]

skill level aside, what you put of your self into the machine is not to be overlooked. so many bikes, restorations and hot rods, speak to that.

mec's monster shows skill but that's the personal touch too.


keep at it sir! 

[MCRider]

YAMIYA Good review in Vendor Feedback.

I ordered 4 parts from them at 9:30EST 4/2 and they arrived at 11:00AM 4/6. All in good order.  Not bad from Japan!  http://www.yamiya750e.com/

I ordered a K0/K1 style small taillight assembly. Nothing on eBay worth having and the replica I got locally was just too cheap looking. The OEM Assy (discontinued here) was complete and top quality. A little pricey at $61, but very nice. They have a complete bracket, rubber cushion, hardware set too, but I already had the bracket.

Also, I needed a petcock for the later style gastanks. There were some OEM on eBay but since I had to get the taillight, I just got their petcock too. A few more bucks but not when you figure in the shipping. One thing from Japan costs the same as a whole bunch of things.  Express mail $24.77.

I got their little rubber "corn" that goes on the old style fender and the license plate lays on it. Also some misc hardware sets. Complete unobtanium in US.

Nice sealed bubblepacks with OEM stickers. Are they really Honda stickers? How do they get away with that from Honda?

[Ecosse]

good news! i have thought about going to the smaller light as i've seen them on some 'mid sized' cb's. have to figure out what fender will fit my 550.

i don't think what you paid was out outrageous; if it's top quality then it beats the alternatives you sited. that price bought peace of mind. 

[MCRider]

good news! i have thought about going to the smaller light as i've seen them on some 'mid sized' cb's. have to figure out what fender will fit my 550.

i don't think what you paid was out outrageous; if it's top quality then it beats the alternatives you sited. that price bought peace of mind. 

yes you're right. It really was reasonable. I won't spend much time shopping for obscure parts again if Yamiya has them new.

To put the light on, you'd need the smaller bracket/w/ install pieces which is about $120. Your stock 550 taillight bracket has 4 contact points? The smaller one is a 1 pointer with 3 bolts in a small triangle pattern of about 1.5", so it might cover 2 stock holes, but 2 others would be left open nearer the seat. You could screw some bolts in to plug them off.

[MCRider]

Good Review posted here: http://forums.sohc4.net/index.php?topic=49569.0

[MCRider]

I've been corresponding with Mark Paris (HondaMan) about fitting his bushings to my swingarm. We got into discussing what i had done to my frame. Long story but in fitting another design of heavy duty swingarm pivot bolt, I had hogged out the bosses in the frame where the SA bolt goes. This in fact was a big reason why this project got stalled years ago. I wanted to reuse this frame for sentimental reasons. It is practically the last original part (along with the crankcases) of the K2 I bought in 1974, raced, totalled, rebuilt, and met my wife on.

So, here's a picture of the fix that Saldana Racing Products did for me. They cut out of the frame, the old bosses, made new ones and welded them in. Can't even tell except for the welds.

You can look across the picture to the boss on the other side, which was replaced also. Spacing and alignment is perfect.



Just goes to show you, no matter how bad someone (me) may screw something up, a good machinist can fix it.

[Ecosse]

I have an increased admiration for this project, knowing some the history. Any obsessiveness in the build is understandable. Obsess away!!

The work on your SA pivot is outstanding too.

[MCRider]

My bike is kinda like the carpenter with the antique hammer: "Yeah I've had this hammer for 50 years. Replaced the head once and the handle twice. Been through a lot with that hammer."

[MCRider]

had a good day. Shortened for Easter get together and Spring Yard chores.

Wire brushed some brake spindles. Been some here that said they wanted or needed one for their rearset mods. I've got 2 extras to sell.

Found some Finned tappet covers. Would sell these too.

The black in between the fins is the aluminum left over from the polishing process. Shiny, never used.
What's up with these axles? One has a hollow end the other solid. Both should be CB750.

Revisit an old issue. Bearing retainer tool. Got the idea from someone here. Piece of strap aluminum (steel would have been better) drill holes spaced right, insert 8/32 screws. 3/8 long with nut.

Drill extra hole so fits all retainers on the bike. Inserted into the retainer, bend the ends down to touch the tire puts pressure on the screws into the retainer, ends of the strap touch the tire, plenty of leverage.

Cleaned a bunch of other parts, getting ready for front end assy.