CB77: Out with the old, in with the new!

A while back I decided to attempt something really stupid and do an EFI conversion on a 1962 CB77 Superhawk. I failed miserably. After a couple years of trying to get the antiquated ECU and poor quality components to work, I finally gave up, and the bike sat in the corner of a shop with barely any sunlight to keep it company. Recently, however, I decided I would trying something slightly less foolish, but still not conventional, and install modern CV carbs on the bike.

It started up and ran, one cylinder at a time thanks to a cracked spark plug insulator, a couple weeks ago before I had to leave on a work trip. I came back a day ago, installed a couple new plugs, bettered my gasoline IV system to run without the tank (more on that later), and got it running on both cylinders. With some rough tuning plugged in, the bike idles and revs phenomenally! The modern carbs offer significantly better response than the old round slides, and allow me the ability to tune many more patches of running conditions to smooth it out. The Elekronik-Sachse crank-fire ignition module is fantastic, and works like a mini-ECU, rev limiter and adjustable advance curves included. I made some throttle cables, wired up the autochoke systems, set the timing, and I couldn't be happier with how it runs right now. It is so much closer to a rideable bike than it has been in the last half decade that I felt I had to start a thread about it!

Current issues I'll have to resolve and will try to document for future reference:

• The clutch cable is very tight. In my attempt to smoothen it up, I broke the lever. I'll have to figure out why it is so tight. There is one big bend in the cable, and perhaps some lube could solve it.
• The rectifier burned up. Not sure why. No shorts in the wiring past the generator, so I'm not sure if it had a bad ground and just took a sh*t. I ordered a new and improved version from Charie's Place.
• Fuel tank isn't on because the petcock is attempting to occupy the same place as the left carb autochoke heater. I have 90% of the solution done, just waiting on one piece. Basically, I plan on relocating it slightly rearward with some aluminum automotive fuel connectors and a lathed brass fitting. Waiting on a custom banjo fitting to be shipped to complete.
• Wiring malarky... brake light turns on when the headlight is on, taillight is on any time ignition is on... usual old Honda stuff I have to sort out.
• License plate bracket is buggered and needs to be remounted elsewhere. It sucks. I hate it. But am far to lazy to make a new one.
• The bolts The Fatherland sent with my Elektronik-Sachse ignition system have heads about 1mm too tall and do not allow the stator cover to be mounted. Either a grinding wheel or some low-pro allen bolts will be the fix.
• Kickstarter is all screwed up and I can't even begin to figure out the solution. I'd really like that working because...
• ...the electric starter clutch is 50/50 right now on actually engaging. Fixing it seems to include removing all the stuff I just installed for the electronic ignition, so I'm dragging my heals. The bike started earlier today when I was simply turning the crank with a small allen key, so I am optimistic that a kickstarter could solve 100% of my electric starting problems.

Stay tuned! As I said, I'll try and document my solutions for all these issues. Perhaps other people will come across them or have come across them, already. Until then, enjoy the few photos and videos I've taken since I pulled all the Ecotrons ECU stuff off the bike and installed these OKO CVK 26mm carbs and Elektronik-Sachse igntion.

For reference, the first video had the rev limit set to 9,000rpm(ish) and I hadn't finished the throttle cables yet, thus I'm giving my bike a double reach around. Spread the love. The second video has the 10,000rpm rev limit dialed in, has improved jet needle and low speed jet settings, and real life throttle cables. Enjoy.

https://youtu.be/wZcL0FdUAjI

https://youtu.be/7MnpP--NBEQ

Update video. Fixed the brake light, tested the autochoke, dialed in some wiring stuff. In the video, that rise to 3000rpm was the bike, not me. I didn't touch the throttle until later, and it was obvious. I believe that the chokes actually made it TOO rich which artificually dropped the revs. Once the mixture got better, it raised up to 3000rpm. The awkward hand waving while checking the crank case temperature was me feeling, for the first time, how much air gets pumped out of the case by that Italian racing vent thing. It is pretty amazing.


https://youtu.be/q6AvnFyb6Iw

That's a good looking machine.

Sounds good, just a little funky til it was at temp.

Thanks, guys. Yeah, it definitely burps and farts a bit until it is warm. Like I said in the video, I think it actually may be TOO rich with the autochokes open. Not much I can do about that except maybe tighten them down more. I've heard of seizing of the needles with these carbs, so I'm not super inclined to mess with it much. It is also wasted spark ignition now with the crank fire system, so that may be burning any unscavenged air/fuel when it is grossly rich. Once it is warm, it runs pretty damn well, so I'm pretty happy about it. I have a set of the correct (one hopes) main jets coming to finish tuning it on the street and I just placed an order for a laser cut bar mount for the AFR gauge. Cheating never looked so good!

Nice one. Interesting carbs and gorgeous bell mouths. CV carbs typically flow around 85% or so of the same sized slide carbs because of the flow disruption from the shaft and butterfly, but those seem to be working fine so far. Race kit seat is a nice touch.

A carb that works well on a CB77 is the CB750 SOHC which has the same 26mm slide diameter as a CB77 but taller oval bore that equates to a 28mm round when fully open.

Yeah, Bob Guynes was trying to push me that way. I am a huge fan of CV's and generally anything with enough tunability to weed out any lean spots. The old stock carbs were terrible and constantly needed adjustment to be right. In the northern Peninsula here in the Bay Area, I was struggling with the 20-30 degree temperature swings we see from morning to late afternoon. Running with the choke partially closed seemed less efficient than a CV carb running with the slide 90% open. Regardless, I couldn't be happier with how this thing fired up and chugged along after sitting for 5 years, and not running for 3.


I have a NOS CYB racing cam, piston set, and valve and spring set that I may build into a spare head I have knocking around. I'd love the tunability of these carbs, still for road use. I may, at that point, go up to a 30mm CVK which appears to use the same manifold fitting I.D. I might port up to 28mm, lose or modify my step down rings I had made, and get it a bit better at higher RPM. That is for a year or so down the road. I want to ride this thing NOW, as is!

Sounds like a plan. Race kit cam will work on the street. The timing and lift are quite mild and the ones I have done cam lift plots of have nice gentle silencing ramps.

30 CVKs might be just what the doctor ordered and with those velocity stacks, they look like sand cast CRs from a CR77.

Sweetness

Haven't had too much time to work on the bike lately, but I got over to the shop to work the lathe and picked up a part that a friend laser cut for me. The turned part I was working on was a brass fitting adapter to relocate the fuel petcock to behind the carbs. It sits a bit lower than I'd like, but I can always go to a -6AN to -6AN banjo fitting instead of the 90-degree joint to raise it back up. The part still needs some work as the tank is being lifted a bit too high for the seat to fit over the back. I'm just happy I guessed correctly on the weird M16x1.5 fitting thread and turned it concentrically on the lathe!


The laser cut piece is a mount for the AFR gauge. The gauge isn't wired up and it needs a couple spacers under it, but I'm happy with the location! Semi-temporary means of "cheating" on the tuning of the bike, once I have it riding!

Okay, 2 steps forward, one big step backward. The good news: I rode the bike for the first time in 5 years today, albeit slowly in a parking lot while it coughed and choked its way around for 5 minutes. The bad news: I can't start it reliably. 2 means of doing it, neither work!!!


The electric starter clutch seems to have finally given up the ghost and I'll have to pull the rotor off to fix it. I'll have to find a good how-to, since there seems to be a sparsity of information about this specific repair. I have a clutch pawl kit, just no idea how to install it! I know it is behind the rotor, which is where my e-igition is, so that'll be coming off. I'm okay with this, but more on that in a moment.


I tried following a Honda 305 forums' guide on lining everything up for the kickstarter, but to no avail. Basically, I cannot fully remove my right side cover without removing a portion of my electronic ignition, and at the time, I wasn't into that. However, I installed the kick lever with the punch marks lined up. The punches are lined up on the gears inside the cover, and the "O's" line up with the lever at about the 2 o'clock position, which checks out to what I've seen. The spring is loose and seems to be applying pressure the wrong way (?). It pulls the lever clockwise on the bike, which would never return it, since CB77s have a forward kick start. With the starter shaft stopped fully clockwise, it does not move anything. It is just rock solid. It moves about 90 degrees counterclockwise and gets equally stuck. There is nothing but flop in the middle. If I put the bike in gear, the shaft is locked completely in place, no flop. Tell me what I'm doing wrong, because it is making me crazy!


The other issue is that I decided to start the bike using the crank bolt. The bike started and ran, but was ultimately a poor decision because I apparently ended up loosening it and the e-ignition is now off. This makes sense since it was running very poorly in the parking lot. I think the fuel I used is not so bueno, either. I'm going to get myself some nice 91 when I'm back from a "business trip" and re-time the ignition once I rebuild the starter clutch, which, as stated, involves removing stator.


A couple photos below.

I'll fix all your problems in one shot. Reset the timing for your ignition and just bump start in 2nd gear for now ;D

Step 1: Trim the ignition mounting plate to allow the outer cover to be removed without messing with the timing.

Step 2: take the ignition wiring through the crankcase with the alternator wiring

Note: in this case those two steps won't obviate the need to remove the ignition to get behind the rotor.

Step 3: grab a spare rear axle and thread it into the rotor. Tighten it down had and then smack the end of the axle a.k.a. puller witha BFH and it should fall off in your hand.

Step 4: Turn it over and remove the three large rollers, springs and cups and clean it all out. Then replace with new rollers springs and cups and slide it carefully over the sprocket. Rotate it slightly as you slide it into place to allow the rollers to retract into the housing.

Step 5: And this is the tricky/messy one. The spring has to be pre-tensioned ie wound up before the cover is installed.

And that is just about the size of it. If you were close to Chicago I'd come over and do it for you or have you bring the bike to my place to take care of it.