Topic: 1972 CB500 "An Inherited Basket Case"

[fantino]

Greetings!!!

I decided to start a new thread because it's been... almost 5 years years since I worked on the bike in earnest and many things have changed. For reference, here is my original thread:

http://forums.sohc4.net/index.php/topic,70066.0.html

Since my last update I have:

-Graduated from engineering school
-Moved to Seattle, WA
-Worked as an engineer in aerospace in the composites manufacturing field (mostly large scale 5-axis CNC of aerostructures and tooling design)
-Moved on to a new mechanical engineering position in thermal test instrumentation where I'm also picking up electrical skills
-Learned to ride a motorcycle and received my endorsement (yay!)
-Bought a 2004 Ninja 250
-Become a better machinist/fabricator
-Spent most of my time and money on various BMWs I have picked up since college

Anyways, I decided recently that I wanted to revive my brothers basket case bike project and get this thing on the road. Many of my former plans have been scrapped either due to changing tastes, practicality, cost, time, etc.

I am focusing more on practical and performance based modifications, shedding weight where I can, improving reliability. Some day I may still pursue a fully faired GP style bike with custom composite body-work (I actually have much more experience in this field now), but for now I am going to keep the cosmetic changes simple and go with a brat-style build.

Following is a detailed list of build plans, any boxes with an [X] are previously completed items, [P] indicates 'In Process'.

ENGINE
[X]Stage 3 port + polish, valve job (Mike Rieck)
[X]HD Springs, new valves, kibblewhite valve guides
[X]Hardwelded shift forks, undercut transmission (Fast By Gast)
[X]New timing chain + guides
[X]Replaced all engine hardware with new stainless bolts
[X]Replaced all shaft seals, o-rings and gaskets
[X]Upgraded to CB550 cylinder head cover with improved rocker design
[X]ARP Stud conversion
[X]New OEM clutch plates
[X]Replace primary chain
[X]CB650 primary chain tensioner mod
[X]Lighten and balance crankshaft (APE)
[X]Replace primary drive rubber dampers
[P]External oil lines to cylinder head
[P]Hydraulic clutch conversion
[X]Balance connecting rods
[X]+1mm intake valves
[X]61mm bore (592cc)\11.5:1 compression ratio forged pistons (DP592R), MLS headgasket
[X]Megacycle 126-20 cam, + hardweld rockers
[X]Anti-friction + thermal barrier coatings
[X]Electrex Race Alternator Upgrade
[  ]Kickstart Delete
[X]Oil pump rebuild


DRIVETRAIN
[X]37T alu rear sprocket, 16T front sprocket
[X]Replace all wheel bearings
[  ]Replace chain

CHASSIS+SUSPENSION
[X]New Bridgestone Spitfire S11 tires
[P]R6 front-end conversion
[P]New fork seals
[X]Shortened CBR600F2 swingarm conversion
[X]New tapered headset bearings
[P]Relocate foot controls
[X]Rebuilt wheels with alu rims and new SS Buchanon Spokes
[X]Replace rear shocks with Gazi Sport-Lites

INTAKE/EXHAUST
[X]4-1 Yosh style exhaust (MotoGPWerks)
[X]CR26 carbs
[  ]Airbox redesign
[  ]Setup + tune carbs
[  ]Data acquisition setup

BRAKES
[P]Replace stock brakes with 4 pot R6 caliper
[X]Replace brake pads
[X]New floating CBR600F3 rotor
[  ]New brake seals
[  ]Cable actuator for rear brake
[  ]Braided stainless plumbing
[  ]Rebuild MC (possibly replace with aftermarket MC for brake and clutch?)

ELECTRICAL
[X]Dyna DC10-1 5-ohm ignition coils
[X]New Points, condenser, points plate
[X]Dynatek Ignition Wires
[  ]Compact indicator lights, LED
[  ]Li-Ion powersports battery
[X]Upgrade to CycleX Optical Ignition
[X]Electrex Race Alternator + Reg\Rect
[P]Mgadget M-Unit Blue, new wiring harness (DT connectors), 2x M-Switch
[  ]Bar end turn signals, LED headlight, 3-in-1 rear lights

BODY
[X]Remove center stand
[  ]Detab frame
[  ]Cognito Moto rearset mounts
[P]Replace hardware with new (stainless where applicable)
[X]Design composite tank and seat
[P]Fab composite tank + seat
[  ]Install composite fairing
[  ]Motogadget Chronoclassic Gauge
[  ]Handlebar controls, cables, grips, etc.
[  ]Repaint frame

GENERAL
[X]Clean and bead blast all aluminum covers, parts, etc.
[  ]Apply for legal title for bike

I'm sure I will come up with more, but I will try to keep track of it all in this first post, updating as I go.

Keep tuned for my next post! I will detail my plans for the hydraulic clutch conversion. I have worked out a simple and straightforward modification to ditch all the troublesome cable-driven components. I will also post some new and old pictures of the bike to show where everything currently sits.

-Evan

[minimo]

Nice and hefty list there, Evan! Stay on target; show us how it's done!

[Tews19]

The list is extensive yet very detailed.. subscribed

[SOHC4 Cafe Racer Fan]

Nice list, indeed.

If you want better performance, and you have not already purchased the S11 tires, I would recommend BT45s instead.  They have a slightly more modern tread pattern but offer much better grip than the Spitfires.

[fantino]

Nice list, indeed.

If you want better performance, and you have not already purchased the S11 tires, I would recommend BT45s instead.  They have a slightly more modern tread pattern but offer much better grip than the Spitfires.

Ahhh, alas, the S11s were purchased many years ago. Noted for my next set of tires, however. I'm sure it won't take long once this is up and running


Hydraulic Clutch Conversion Details

A quick overview of my plans for a conversion to a hydraulic clutch. Since this is a common failure point of the CB500 and is a finicky unit requiring adjustment and lubrication, I have long desired to replace this mechanism with a simple hydraulic actuator. I was partially inspired by this CB550 hydraulic clutch conversion:

http://www.dotheton.com/forum/index.php?topic=26406.0

This is only partially applicable to the 500 due to the revisions in clutch design. I'm not crazy about the look of a large hydraulic cylinder sticking off the cover like a big wart, nor do I like the hose routing.



Luckily the 500 clutch has the benefit of having a nice deep hole already in line with the clutch rod on the opposite side cover, and also does not require sealing from engine oil. The bore through the clutch cover where the adjustment mechanism resides (item 5) measures 1.063". I was hoping it would have been slightly under an inch as I could have installed a larger threaded hydraulic cylinder with no additional modification, but so it goes. My current plan:

• Mill flat the lip on clutch adjuster bore on outer side of engine cover, maybe ~.025 to .050" deep
• Tap thru clutch cover hole @ 1 1/8"-12 UNF. This is only a 55% thread, but should be sufficient given the hole depth and a little loctite
• Fabricate and install cylinder carrier (See attached dwg)

This will allow installation of a threaded body hydraulic cylinder, like the one in the attached Vektek drawing. I'm evaluating equivalent parts, but the body diameters appear to be relatively standardized. This type of cylinder is nice because they're:

• Compact + Light (small enough to carry a backup on a long trip)
• Relatively inexpensive (<$100)
• Hard-anodized for good corrosion protection
• Easy to adjust (simply turn the unit further in or out as needed)
• Includes an internal return spring to prevent preload on the clutch
• Good wiper design, built to withstand high-contaminant industrial applications
• Rebuildable

I still need to sort out the following details:

• Pushrod throw
  -In order to maximize clearance between drivetrain and exposed area of the cylinder, I would like the body to be as short as possible
• Pushrod length
  -A new pushrod will most likely be required. The stock unit is hollow and made of multiple pieces pressed together, so it cannot be readily modified
• Linear force required to disengage clutch
  -Needed to correctly size clutch master cylinder
• Plumbing
  -I would like to run a hardline from the cylinder thru the bolt clearance hole adjacent to the clutch adjuster hole. I can then transition to a flexible braided line and exit via the original clutch cable location

I won't be able to finalize these details until I get the rest of the motor back down to Seattle from Bellingham, but I will likely get started on the clutch cover modifications sooner rather than later.

[EDIT]

Edited for clarity. Trying to cut down on my tendency toward verbose paragraphs.

[calj737]

Hot dang! Love the hydraulic clutch plan. I'll be following that closely.

[Stev-o]

Hot dang! Love the hydraulic clutch plan. I'll be following that closely.

+1.  Finally someone attempting it. Regretting selling my 500 now!

[lightsareout]

I am going to keep watching your build! Can't wait to see your progress

[fantino]

I have a set of Excel rims and spokes on order so I can ditch the heavy steel rims. Should see those show up in a few weeks as they're build to order.

Glad to hear folks are excited about the clutch conversion. Now I'm feel the pressure to make it work!

I mulled over the hydraulic cylinder carrier for a bit and decided to make a few changes. From a design perspective, I wasn't all that excited about leaving so little material between the thread crest and the outer wall of the clutch cover, at least not in thin wall cast aluminum with unknown properties. Seemed like an invitation for crack propagation during use or thread forming. I also didn't really wish to buy a large tap I have little use for.

Revisions include (see attached DWG):

• Removal of external threads
• OD sized for press fit
• Overall length increased to extend past inner lip of clutch cover
• Groove added for snap ring (McMaster pn 98410A136 or equiv.) - Added safety to ensure hydraulic carrier won't back out under load

I  machined the carrier after work today. The OD is a little undersized for a good interference fit, so I will install with Loctite 680 for extra hold and to prevent rotation. I'm confident the snap ring will be sufficient to hold it all together under force. I'll snap some pictures when I assemble everything.

Based on wear marks on the push rod, it appears the clutch throw is ~0.625". I feel okay proceeding with a cylinder capable of 0.75" of throw, should leave a little extra so I can maintain a slight gap between the push-rod to ensure no preload. I ordered a Hytec 100171, which is more or less equivalent to Vektek 20-0105-07, but about $20 cheaper, but with a smaller piston area.

[calj737]

Another option might have been a 2 piece design. Threaded insert from the outer, into a threaded jamb nut/sleeve on the inside. After all, you're in control of the OD/ID of the adapter. That way, you could eliminate any stress directly onto the cover itself.

By the way, have you seen the Davies Motorsports dry clutch modification? Its linked to a 6 speed gearbox (lose the kick starter though)? A hydraulic dry clutch would be a very cool modification!

[fantino]

Another option might have been a 2 piece design. Threaded insert from the outer, into a threaded jamb nut/sleeve on the inside. After all, you're in control of the OD/ID of the adapter. That way, you could eliminate any stress directly onto the cover itself.

By the way, have you seen the Davies Motorsports dry clutch modification? Its linked to a 6 speed gearbox (lose the kick starter though)? A hydraulic dry clutch would be a very cool modification!

I'm a bit lazy on the lathe; The fewer threading operations, the happier I am I did make a lock-nut for the outer side of the cover to lock the hydraulic cylinder in place, however.

The dry clutch Davies put together is snazzy!!! Probably out of the scope/budget of my project, but very impressive stuff nonetheless.

Here are a couple pictures of the hydraulic carrier mocked up in the clutch cover:




I'm not much of a machinist, but I think everything fit up pretty well and doesn't look horribly out of place. Tolerances are close enough to make good use of Loctite 680 in the final installation for extra holding power, and once the snap rings arrive everything will be nice and secure. I should have taken less off the locknut and planned to use one size larger of wrench, but oh well.

I picked up a cheap ($25) set of clutch/brake masters + handles for plumbing mock-ups and testing. Will likely replace these in the final iteration as they're cheap and a bit ugly for a bike with no fairing. Progress will be minimal until parts start showing up in the mail in the next week or two.

I may try to get my crank off to APE in the next week or two for balancing and lightening.

[kslrr]

Very well planned out.  Like a true Engineer.  Following.

[fantino]

TL;DR Update Summary:

• Scrapped Hytec hydraulic cylinder, replaced with higher quality + shorter Vektek unit
• Picked up cheapo master cylinders for system testing and mockup
• Rebuilt rear wheel with Excel aluminum rim + stainless buchanan spokes
• Sent crankshaft to APE for lightening + balancing
• Rediscovered crankcase damage from primary chain. Will repair. Will add 650 primary chain tensioner to list.
• Planning for oil + hydraulic plumbing underway
• Electrical system planning underway - MUnit V2, MButton, etc,

I wasn't happy with the Hytec cylinder I ordered (required too much modification for plumbing), plus once I got my engine back home I realized I misread the wear marks on the pushrod and the overall throw of the clutch is only .200".

I ended up picking up Vektek p/n 20-0105-03, with .38" throw. It is threaded for a #4 UNC fitting (7/16"-20 thread) but I will machine the top .050" off to remove the o-ring groove so I can use a banjo fitting. I also installed a #8-32 low head stainless screw onto the end of the shaft to act as a replaceable wear surface. Here is everything installed:





I plan to run a banjo fitting with a hard-line through the hole in the cover adjacent to the cylinder and up through the cable pass-through for the original clutch mechanism. From there I'll fix an AN flare fitting onto the cover to run a braided cable up to the clutch M/C. Unfortunately I can't really test the system until I put the lower half of the engine back together.

Speaking of M/C's, I bought a pair from eBay that were BRAND NEW for $25. I don't know how anyone makes any money on these parts. They're ugly (esp. for a bike without fairing) and I'm sure they'll blow their seals in short order, but it gives me something to use for testing and mock-ups until I find a proper set.



I received my aluminum Takasago Excel rims and stainless buchanan spokes. I've rebuilt the rear already, need to pop the tire off my front wheel to rebuild the front.



I picked up the engine from my folks place and got everything split back apart. The crank is off to APE to be balanced and lightened. I wanted to do this years ago but couldn't justify the extra cost, so I'm excited to get the bottom end where I want it. I will also likely send my rods off to Mike Rieck to be balanced, polished and shot peened in short order.

Unfortunately I discovered damage in the crankcases I had forgotten about. The primary chain had eaten through the passage from the oil pump to the oil filter. It didn't make its way through and I did replace the primary chain with a new unit the first time I split the cases. Nonetheless, I would feel a lot better having the gouge welded over, plus I can fill in the stripped bolt hole in the case I never properly repaired.



With this re-discovery, I am seriously considering the CB650 chain tensioner mod. So I'm in the market for a good tensioner assembly, oil pickup and oil pan. If I'm getting additional welding work done, I may try to just have the mounting bracket welded on to avoid adding another potential leak location by bolting through the cases.

Nothing else particularly exciting happening. I'm waiting until next month to purchase pistons and have the cylinders reworked. Right now I'm mostly working on planning all the plumbing for the brakes, clutch and external oil lines. I'm also investigating oil coolers and replacing the stock filter with a spin-on filter attachment.

After reading other project threads and discovering the MGadget M-unit V2 I am very happy to say I've found the perfect solution to my electrical system. I plan to run it with the M-button to minimize cable runs. I can't think of a cleaner and more robust solution to rewiring the bike.

That's all for now!

[calj737]

Skip the M-Button, it has a difficult time cohabitating with our ignition systems. You are likely to get behavioral anomalies unless you run full suppression wires and use only steel bars. The M-Unit is so easy to wire with momentary switches, that runs from the switches can all be 22AWG, and from the M-Unit to component 18AWG.

To really clean up your wiring, use their M-Lock keyless ignition and one of their gauges. 

[540nova]

I knew calj737 would come in here on that! . He's our Motogadget guru, so when Cal speaks, I listen.


1974 CB450, 2006 CBR1000RR

[fantino]

Thanks for the tip You're right, running a bundle of small gauge wires will be a lot less hassle than filtering and shielding circuits if the m-button bus signal is as sensitive to EMI as you're saying. I suppose I shouldn't be surprised that these older bikes generate a ton of noise, solid state electronics probably weren't too high on the list of design concerns back in the day.

The keyless ignition system is definitely in my sights. I've had my eye on the Chronoclassic tach for sure. I'm trying to keep cost and scope from going out of control, but that's never been my strong suit 

[540nova]

You won't be disappointed with the motogadget M unit, that thing is awesome and if you are wiring your bike from scratch it makes it a breeze.


1974 CB450, 2006 CBR1000RR

[calj737]

So, if you do opt for an MG gauge, plan for an extra momentary button to control the display screen of the gauge. Most (including the ChronoClassic) of their gauges have an analog gauge but also have an LCD screen to allow you to toggle through other information (speed, voltage, ODO, gear, Oil pressure and temp ((requires extra sensor inputs) and RPMs). To scroll through them and/or reset their values, that momentary is needed.

The MG M-Switches in 3-way are my preference, though there are other brands that work too. I set mine up with TURN L on left side, TURN R on right side, then Menu on R, START on R front, and HI/LO left, HORN on L front. It works out very easily and if you later change your mind about button assignments, simply move the wire on the left side of the M-Unit input. Done 

The Chromo comes with a Hall sensor, that typically I orient opposite the drive sprocket bolts, under the left cover. With your hydraulic pump there, that may not suit you. The gauge ships with a 9 plug and 6 plug connector, and simply organize them into a single, all wires used, then abandon the other and tuck it away. The overall best benefit of the system: NOTHING IN THE HEADLIGHT BUCKET!!!!!

Can't wait to see your motor completed and get a report on the clutch mods!

[fantino]

calj737, I'm convinced... I'll likely budget for a chronoclassic gauge to go along along with the trick M-unit and keyless ignition. I'm not normally one to be swayed by gadgetry... but it's just such a clean and well put-together package. I'm digging their bar-end turn signals as well.

I had a hard time finding any local welders who wanted to touch my crankcases, but I took it upon myself to fit a primary chain tensioner from a CB650 onto the bike. Now that it's on there, I don't think repairing the gouge is worth the effort or cost. If the chain makes it anywhere near the cases now... I've got bigger problems!

I followed the advice from this excellent thread:

http://forums.sohc4.net/index.php?topic=80690.0

I made a few minor deviations from Heinz's drawings to simplify machining setups (no fancy outside radius for me!) and I have yet to drill the thru-holes into the lower case (I need to track down my short 90 degree air drill for clearance).







Heinz was correct that by bending the top tab to 90 degrees or less, there is in-fact clearance between the tensioner assembly and the oil pan. No need to fit the deeper 650 pan or hassle with the oil pickup (if you have a 550). I confirmed by sliding some paper between the tensioner and pan all bolted up (very scientific).



Otherwise... Nothing terribly exciting going on. Finished lacing and truing the front wheel. Crank is still at APE, rods are with Mike Rieck.

Still trying to make a final decision on whether I go with Dynoman's 10.5:1 or 11.5:1 compression pistons. I'm leaning towards the higher compression pistons, because... Well, because I can. It doesn't sound like these bikes are too troublesome under 12:1 with careful tuning.

Once I have pistons in hand, I'm going to send them off to have the domes and skirts coated. I will also have my rod and crank bearings PVD coated at the same time - I don't think it makes much of a difference on the journals once the bike has oil pressure, but anything to help reduce friction on startup is good in my books

http://www.hotrod.com/articles/hrdp-0612-engine-coatings/

I thought this was a good article with some solid numbers behind it on the benefits of engine coatings. I agree that most of the gains are going to be found in reliability + longevity, rather than power, although thermal barrier coatings on pistons definitely seem to have an impact on lowering cylinder head temps on air-cooled motors. This has to count for something in tuning a reliable, higher compression motor.

[Camrector]

I would think maybe a different cam if going with high compression Pistons. The 650 cam is a nice mild upgrade but you can do better. I was bullyed here to into the Megacycle 126-20 cam for my 550 . I'm using the 11.5 592cc pistons from dynoman. Valve reliefs in the piston doesn't need to be altered with this set up

[Camrector]

Amazing work btw

[fantino]

I would think maybe a different cam if going with high compression Pistons. The 650 cam is a nice mild upgrade but you can do better. I was bullyed here to into the Megacycle 126-20 cam for my 550 . I'm using the 11.5 592cc pistons from dynoman. Valve reliefs in the piston doesn't need to be altered with this set up

Yeah, I guess that's why I'm having a hard time deciding - If I go higher comp I figured the cam would be the weak link in the performance chain, and so it adds another item to the list. But hey, I've already gone all out on the porting and have resigned myself to picking up a set of CR26s in a few months. Just further and further down the rabbit hole...

How streetable do you find that combo? Keeping in mind the only bike I've spent any real time on is my ninja 250 - so I'm used to keeping my revs up (I rarely dip below 8K on the ninjette, haha).

Amazing work btw

Thank you! Although I wish I had made more progress on this bike years ago, it's kind of a blessing that I didn't. Not that I'm much of a fabricator, but I feel a lot better prepared (and better funded) to tackle all the work needed to get the bike where I want it.

[calj737]

If you bump up to the MegaCycle 126-20, both the cam and rockers must be hard welded. The CR-26s will be a great benefit for breathing, but, you need to really pour some work into the head to make it all sing. Oversized intakes, hefty porting, and matched intake runners to get the real bang for your buck. And have the underside of your pistons coated with an oil shedding coating too. This keeps the crankcase oil from collecting underneath and absorbing heat through the piston.

BEFORE you have your pistons coated, dry assemble the motor. The 126-20 has enough lobe on it that small amounts of milling in the head galleys is required, plus, the underside of the rocker arm needs just a touch, AND the piston will very likely need the valve relief cut deeper. Stock these pistons sit down in the bore between 32 and 40 thousandths. You'll want to deck the block to level them out and get the best squish possible with high compression slugs.

Some pictures for reference:

[540nova]

And I thought Calj737 was just a Motogadget expert!


1974 CB450, 2006 CBR1000RR

[calj737]

One more thing: have the rocker shafts coated with DFL or similar too. This really helps the arm prevent any dry start friction and warping. Modern coatings on these vintage bikes help an "inch at a time" in longevity and reliability. Since some hard parts are no longer made, caring for them with  "Spa Day" treatments is my approach. May be silly and expensive, but when you put this many thousands of dollars into a bike, I consider it investment protection. Anything to lower the friction and engine oil temps gets my attention.