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

[Zaipai]

That is just fantastic. Love the air shock mod's.. Fantastic detail as always..

.: Scott :.

[Ecosse]

That is just fantastic. Love the air shock mod's.. Fantastic detail as always..

.: Scott :.

very clean set up. looks cool too.

good luck with the blaster. 

[RAFster122s]

On the air valve manifold bolted to the plate. Is the manifold a commercial item or how was it made.
I see that it uses compression fittings for the air hose on the shock caps and at the manifold for the schraeder valve. I just haven't see a schraeder valve that was threaded on both ends.

Thanks!

David

[MCRider]

On the air valve manifold bolted to the plate. Is the manifold a commercial item or how was it made.
I see that it uses compression fittings for the air hose on the shock caps and at the manifold for the schraeder valve. I just haven't see a schraeder valve that was threaded on both ends.

Thanks!

David

ITs an off the shelf automotive item for air shocks. Its a "T", the under the plate hookups are compression rubber O Rings set into the brass, the hose pushes thru the oring, the white plastic nuts tighten down on them. THe single schrader sticks up thru the plate and is topped off with the stylish "Skull and Crossbones" valve stem cap.  

That way the pressure in each tube is always balanced.

I'll get some pictures later.

[MCRider]

Here tis:
"T"

One schrader:

Oring in recess of the branches of the "T"

Hose fits into ORing, flange in nut presses down on ORing. Hand tight, then 1/16 with a wrench:

Off the shelf part from auto store, though they may keep them behind the counter, for air shocks.  As mentioned, this kit was put together in 1980, and I used it for 15 yrs, 50k+ miles, never a problem. Hit it with the air hose, then check it. Each time you check it you lose a little from the gauge. So you have to know your gauge and get a feel for it. I'd pump it to 20psi. Then each hit with the gauge would take 5psi out. I usually ran 5psi with the bike on the center stand and normal weight on front wheel.

I just needed to shine it up, replace the nuts and hoses, make decent bracket.

It was a common mod in 70s, then the factories did it in the 80s/90s. Some even tried to go air only, no springs, but that never worked out.

Now not so much. But I like it.

[Zaipai]

Very slick.. If I ever do that I will for sure do it the way you have it.. Its the best setup I have seen so far.

.: Scott :.

[MCRider]

Very slick.. If I ever do that I will for sure do it the way you have it.. Its the best setup I have seen so far.

.: Scott :.

Thanks, I always thought so.     Toughest part is drilling and tapping the caps. My buddy did mine for free. But I'd bet its a $30 item at a machine shop.

[wannabridin]

if only there were a way to make the whole job prettier.  i'll admit it's cool looking and a great conversation piece, but it just makes that whole area too "busy" for me... 

[Ecosse]

you could run a valve for each side; i think that's how my buddy's cm450 is.

mc, i sold scores of those air shock kits and had them in my mustang, charger, and also in my duster before modifying it more for handling. full air shocks (not air assisted) suck for performance driving.

[MCRider]

you could run a valve for each side; i think that's how my buddy's cm450 is.

mc, i sold scores of those air shock kits and had them in my mustang, charger, and also in my duster before modifying it more for handling. full air shocks (not air assisted) suck for performance driving.

Most of the factory setups I ever encountered did not have balancers, which struck me as odd, although I'm sure many must have. My wife rode a ZL600 Eliminator for many years. A cruiser rear with a shaft, a Ninja motor (70hp and she liked to use it) and a Ninja air fork. A separate filler on each side, no balancer.

I couldn't make one like that, gotta have balance.

[Brown Bomber]

you could run a valve for each side; i think that's how my buddy's cm450 is.

mc, i sold scores of those air shock kits and had them in my mustang, charger, and also in my duster before modifying it more for handling. full air shocks (not air assisted) suck for performance driving.

Most of the factory setups I ever encountered did not have balancers, which struck me as odd, although I'm sure many must have. My wife rode a ZL600 Eliminator for many years. A cruiser rear with a shaft, a Ninja motor (70hp and she liked to use it) and a Ninja air fork. A separate filler on each side, no balancer.

I couldn't make one like that, gotta have balance.

My '87 Kawasaki Concours has only one valve on the fork, and a balance tube between the forks. All '86-'93 models came that way stock. I also had a '82 Night Hawk 450 with a very similar stock set up. I'd like to put one on my 750, and my 500, but I have enough projects. A little air really makes a difference.

[CBJoe]

 '81 CB650C had air forks..... valve on 1 fork cap w/ a crossover tube to the other cap. 

Doesn't the CB750 have 35mm fork tubes like the 650??? Be interesting if the caps from the 650 would fit on a 750.
I've got an extra set if you want to borrow them.

Joe

[Ecosse]

my friend with the cm also has one of those (model?) 10 speed cb900s. i'll have to see what it's got.



now i'm confused... is this the air fork thread? 

[Jinxracing]

Most of the factory setups I ever encountered did not have balancers, which struck me as odd, although I'm sure many must have. My wife rode a ZL600 Eliminator for many years. A cruiser rear with a shaft, a Ninja motor (70hp and she liked to use it) and a Ninja air fork. A separate filler on each side, no balancer.

I couldn't make one like that, gotta have balance.

Great looking build! Out of curiosity, why is it so important to have balanced air pressure between the forks?

[CBJoe]

Someone please correct me if my wording is wrong ....

A difference in pressure will cause a different rate (or amount) of dampening between 1 fork and the other.  Kind of like only replacing 1 worn spring instead of both.

Joe

[MCRider]

Someone please correct me if my wording is wrong ....

A difference in pressure will cause a different rate (or amount) of dampening between 1 fork and the other.  Kind of like only replacing 1 worn spring instead of both.

Joe

Yeah that's exactly right. And without a balance tube, I'd say its outright impossible to get each side the same. Other than propping up the front end, opening each valve to allow atmospheric pressure to reign, close the valve, and set the bike back down on its own weight. Then you just live with whatever it is.

[Jinxracing]

Someone please correct me if my wording is wrong ....

A difference in pressure will cause a different rate (or amount) of dampening between 1 fork and the other.  Kind of like only replacing 1 worn spring instead of both.

Joe

I think you mean spring rate, but I get what you're saying. It shouldn't matter though, should it? Marzocchi made lots of forks in the '70s/'80s that had a spring in only one leg and damping control in the other. If you were to remove the spring from one of your fork legs and put a stiffer spring in the other, the forks should still work the same way, right? The front axle binds the legs together so well that they become a single unit. I think that if both legs being balanced were that important, there would be a lot of talk out there about testing fork spring tension for evenness, carefully measuring fork oil to within 1/10cc per leg, etc.

For example: If you were to eliminate the balance tube and fill one leg with air to 5psi and the other to 6psi, I think you would simply have a total air assist of 5.5psi for the forks as a whole.

The balance tube setup is cool to look at, I'm thinking that it's just not necessary. Or am I missing something?

I remember putting air shocks on an old VW bug I used to have. Being a car, it did need the balance tube. I also remember the fittings failing on a few occasions, causing one corner of the car to sag. Not a big deal in a car, but if that balance tube fails are you going to lose significant pressure in the forks? Would kinda suck if it happened halfway through a corner. 

[Brown Bomber]

I would want equal pressure in both forks. Fork tubes are long and skinny compared to car shocks, and flex much more than people think.

[MCRider]

Someone please correct me if my wording is wrong ....

A difference in pressure will cause a different rate (or amount) of dampening between 1 fork and the other.  Kind of like only replacing 1 worn spring instead of both.

Joe

I think you mean spring rate, but I get what you're saying. It shouldn't matter though, should it? Marzocchi made lots of forks in the '70s/'80s that had a spring in only one leg and damping control in the other. If you were to remove the spring from one of your fork legs and put a stiffer spring in the other, the forks should still work the same way, right? The front axle binds the legs together so well that they become a single unit. I think that if both legs being balanced were that important, there would be a lot of talk out there about testing fork spring tension for evenness, carefully measuring fork oil to within 1/10cc per leg, etc.

For example: If you were to eliminate the balance tube and fill one leg with air to 5psi and the other to 6psi, I think you would simply have a total air assist of 5.5psi for the forks as a whole.

The balance tube setup is cool to look at, I'm thinking that it's just not necessary. Or am I missing something?

I remember putting air shocks on an old VW bug I used to have. Being a car, it did need the balance tube. I also remember the fittings failing on a few occasions, causing one corner of the car to sag. Not a big deal in a car, but if that balance tube fails are you going to lose significant pressure in the forks? Would kinda suck if it happened halfway through a corner.  

All good points and theoretically I could agree with them. Practically, the front axle set up is puny and not intended to effectively transfer fork loads as if it were one. The bottom legs of my 650 Hawk are twice the size with a larger diameter axle. It is still not strong enough that additional bracing isn't needed.

Many racers I have run across are very picky about having the same amount of oil in each leg, I've heard heated discussions about it. And about matching the lengths of the springs. Say if one had fatigued faster than the other due to quality control, both would be replaced. Admittedly I'm in that camp.

But you may have a point and its not necessary. I don't have absolute proof either way, but my opinion.

AS far as failure, its not any more likely than failure of any of many other components. It is an extra worry I suppose. But failure simply means falling onto the spring thats there, with the leak being similar to a leaky fork seal that people ride with all the time.  The factorys used them quite a bit thru the 70-80-90s and failure was not an issue.

So I see what you're saying, and you could be right. But my build theme has always been to put all the stuff on it I either had and liked (dual discs, air forks, steering damper) or never had and wanted (fork brace, frame gussets, smaller wider wheels, etc) just cuz.        (as long as there was a chance they were of some value, and were not life threatening)  The chrome hardware and acorn nuts are just there because I'm silly.

[Jinxracing]

I hope I didn't come off like I was attacking your build...I'm a belts and suspenders type of guy too. I guess I was just approaching it from a philosophical point of view. If I were to add air assist to my forks, I'd put in a balance tube too, even though I'm convinced it's unnecessary. 

I think that based on my past experience with the plastic air tubes that you're using, the only thing I would do differently would be to see if a braided steel setup could be used.

I like your build...keep it up. I'm looking forward to seeing it finished!

[MCRider]

I hope I didn't come off like I was attacking your build...I'm a belts and suspenders type of guy too. I guess I was just approaching it from a philosophical point of view. If I were to add air assist to my forks, I'd put in a balance tube too, even though I'm convinced it's unnecessary. 

I think that based on my past experience with the plastic air tubes that you're using, the only thing I would do differently would be to see if a braided steel setup could be used.

I like your build...keep it up. I'm looking forward to seeing it finished!

No, no offense taken, just a long winded response post. I appreciate the comments and the interest. 

I'm comfortable from experience with the plastic tubes, braided steel would be better. The aftermarket aircaps use the plastic and I used it for 15 years, 50k miles, should be OK.

Man no one wants this done more than me! I've got trips planned. Want to go back to places it's been in previous lives.

Going to salvage yard tomorrow for missing parts.

[MCRider]

Well, I spent at least 6 hours on ebay looking for a fender. i am obssessed with this. The one i had made I just can't go with. So I'm emailing sellers all over for dimensions, etc. and the prices these guys want for trash and near trash, $35+ for fenders with obvious dents, mortal wounds, etc.

Then Bruce and I took Thursday 2.5 hours down for a personal visit at Cycle Recycle part II. Boy that Rob (owner) is a trip. He has red flames tattooed from his wrists up to his elbows where the sleeves of his waist coat take over with flames up to his hat. i shoulda got a picture, but i wa afraid.

Taking our lives in our hands we slithered between two ceiling high racks of seats and fenders, the aisle about a foot wide and began pulling fenders off the rack, one by one. Sweat dripping, hands bloodied, psyches racked with anxiety of being crushed to death at any moment, left for the next scrounger to find us...

We found 2 CB350F fenders, one had the front bobbed a little, the other complete. A virtual lock in looks to the front I had on Phaedrus I, bobbed front with the stay on the bottom. Looked like the later 750 fenders did. But the blade has that 1970s look, no sides, shows the whole tire...AND its an 18" diameter rather than the stock 750 19", fitting my new 18" wheel. I'll try to get a pic.

Working late in the shop tonite, gotta get some headway.

[bwaller]

I've been in spots like you descibe. Glad you lived to tell about it! 

[MCRider]

So having scored the CB350F fenders, we proceed to remove the bracket off the bobbed fender. (I think someone here actually suggested a CB350F fender some time ago. I didn't think I could ever find one, let alone 2. $10 for the bobbed one, $35 for the complete one with a small manageable dent.)

here's Phaedrus I, about 1994, running the ridges of northern KY. See how the fender was bobbed? I always liked that fender. Tho many didn't. But its a 19" and I knew I would need at first a 17", but when that fell thru, and I went with an 18", well thats what we needed. The one I had made always bothered me, partly for some fab issues, but also because it wasn't from the 70s which is part of the theme, keep it period correct. The CB350 fender is a 1972, and a virtual duplicate of the 750 fender, but in 18".

So we grind off the inside head of the rivets.

Several minutes and you can drive out the rivet. Using the rubberized handle of a pair of pliars to drive against...



Got the soda blaster working: Does the job but uses media pretty fast.

You can see the rust in prior pictures, compared to this after.

best to use other means like a wire wheel first and finish with the blaster to conserve media.
I had pictures of a yellowed brake panel, can't find it. But to answer the question, the blaster makes instant work of removing yellow lacquer and preparing the surface for polishing.
Did it outdoors, left the remains on the driveway. The evening rains made a great cleanup, nothing left over. Be sure to note what's downwind as it will get covered.
Replaced the rear strut and tiewrapped the bobbed fender in place. Its a little low in the back, can be raised to put more in the front.

If the front is too bobbed, and water comes off it and back into my face, we can make another one with the full fender, not so short.

Fianlly, my buddy who passed a few months ago, who had the new Suzuki parts, well his son called me and said he'd like to get them sold. So I picked up 12 buckets half full of brand new Suzuki parts era 70s. I'll be putting them on eBay to raise some cash for the beneficiary and for my project.

[Terry in Australia]

G'Day Ron, you know I love your build mate, but that fender sucks. Sorry, but I think it has been cut way too short Ron, and just doesn't look good. There are better 18 inch front fenders out there, I used a Honda CM400 front fender on a CB750 with 18inch front wheel 30 years ago, the CM400 was a pretty forgettable bike, so you can probably still buy one new from Honda. Cheers, Terry.