Topic: Vintage Speed Part Mashup - 1976 CB750F

[slikwilli420]

I have finally decided it is time to start my project thread. I have been doing a lot of reading on certain topics to get a decent knowledge base before I dive in. I dont have a ton of pics but am really trying to make sure I document everything both for me and for others to reference. There are things I am doing that I dont think have been done before but then again, I have not seen everything quite yet. I have tried to assemble a great collection of vintage speed parts to create something that has a really old school feel. Here is a rundown of my intentions.

1976 Honda CB750F Super Sport
Front end components:
     Betor 35mm forks with Race Tech springs/emulators
     Ceriani-type 17mm axle
     Lester mag wheels
     Thinned and drilled rotors (thanks Godffrey!) assembled with ARP 12pt bolts/nuts
     Betor upper/lower aluminum triple clamps
     AP Lockheed CP2696 calipers bolted to custom brackets with SS brake lines
     Manx-style fiberglass fender with aluminum stays
Gauges/controls:
     Speedhut 10K RPM/140MPH GPS Speedo/Tach combo
     0-100PSI Speedhut oil pressure gauge - signal fed from oil galley hole
     Tomaselli adjustable clipons
     Ceriani style headlight ears
     Stock hand controls
     Rearsets - undecided
Tank/body:
     Rickman steel inner tank with fiberglass cover - being converted to oil/gas tank combo
     Rickman tail piece with battery tray underneath
Rear end:
     Dresda-style swingarm (thanks Voxonda!)
     Lester 18" disc rear wheel
     Thinned and drilled rotor (same as fronts)
     Original AP Lockheed CP2195 caliper with custom aluminum mount
Frame:
     Frame splice kits to remove top rails for head removal
     Detab
     Gussets at key corners and X bracing over swingarm
     Finish all welds
     Relocate electronics from left side to a cover tucked under seat frame
     Stock oil tank - GONE!
Engine:
      - Anywhere from stock to totally insane
     CB900 oil cooler with custom plumbing to new oil tank
     Weber 40DCOE sidedraft carbs with custom manifold/linkage/mounts

That is the rough plan for now. This has been an ongoing project for about 10 years and has taken many forms but I think I have the vision and finances to make this happen.

Here are a couple of pics including the bike as it sits now, the oil/gas tank combo, the front brakes, and the Weber manifold.

[seanbarney41]

I like where you are going and what you have ...subscribed

[754]

Did you have to shave back of the calipers ?
 Are you getting the Weber manifold or block cut? More than 1 ?

[slikwilli420]

I may end up shaving the back of the calipers,  or will have to space the rotors out a bit. As for the manifold I will be getting the plate water jetted in a couple weeks then will have the four spigots welded on. It will be very similar to the RC style and will have provisions for the linkage to mount to. I am planning to have 2 made up just on case.

[754]

Make a few more, I can make some spigots in the RC Style
 The cutting should be easy once its programmed.

[slikwilli420]

Mini update. I was playing with my new Hobart Handler 190 MIG welder today and got some gussets made up and welded in. I just need to clean up the welds a bit and they will be a done deal. The frame splice kit was basically finished as well.

[slikwilli420]

I did some additional work on the gas/oil tank combo last night. I wanted something different and this also gave me the opportunity to open up the triangle to lighten the look of the bike. The tank was cut in half and I also removed a 1/2" strip so there is air gap between the two to keep heat transfer at bay. I will probably have some thermal tiles between them as well. The two halves will be be finished up then have tabs of some sort to connect them back together so the cover will fit properly.

The oil tank will be plumbed with -10AN lines feeding through an oil thermostat and to an oil cooler and return on the other side of the tank. The filler cap will also come up through the cover and I will make a gas cap that is similar in style.

A few goodies arrived today, including my Dresda swingarm copy from Voxonda, my SpeedHut gauges (speedo/tach combo and oil pressure), and the linkage kit for my 40DCOE Weber carbs.

[slikwilli420]

I recieved the Race Tech emulators and springs for the Betor forks I will be using. This was another great learning experience this project has given me. I had never even replaced fork seals before, and now I have done a whole set of forks. They are buttoned up and I have guesstimated on preload spacers based on the RT instructions. Now all that is left is to clean up the lower legs and decide on anodizing/powdercoat/polish/paint.

The rear axle on the new Dresda swing arm is too short and Voxonda suggested the axle from a DOHC 900F model which I found basically NOS on eBay.

I also added a few other things to mix it up a bit. There was an NOS Tommaselli Super Pratic throttle on eBay that needed to be on my bike. I will either just remove the throttle tube and keep the right hand control or find a new control altogether. If I go hydraulic clutch I will have to change both.

As to mounting the Weber carbs, I will have the manifold plate waterjetted this week and then start mounting the linkage. Here is a pic of it mocked up.

[754]

Youbmay want to mount those on coroplast or thin aluminum and put them in place to check clearance.
I forgot to measure spigot length off the RC manifold today, will try to get it tommorrow. Let me know if you need spigots made.

[slikwilli420]

Although I didn't test mount them on anything when I held them up they seemed to have enough clearance. I will be shortening the ball joint rods just to make sure. If I take 1/4"of either end that still leave me with plenty of adjustment.

[slikwilli420]

Working on a couple of projects, one for the electrical and one for the front end. For the front end, I was originally going to use the triple trees that came with the Betor forks that are going on, but there was modifications needed to adapt a new stem, in addition to them being a different offset and about 1/8" narrower between stanchions. So then I decided to use an idea that I had seen on another bike, to mod the original triple trees by smoothing them out, removing the handlebar clamps, and the gauge/idiot light mounts for the bottom. So I will end up a set of top/bottom clamps made from 2 uppers that will be all relieved of all the non-essential parts. I hope to go from the pic of my two clamps to the one you see in the other picture.

My other project is relocating the electronics to under the seat. My idea uses the threaded holes already in the frame for the battery/tool tray. The new plate in the pictures will have four posts that will raise the panel up higher under the seat so less is visible in the triangle. I will also make a cover that has perforated/screen/louvers for look and air flow. The reason I mounted them facing down instead of up as others do is so it's easy to access the fuse block in the event of a blown fuse. The battery will go into a tray under the tail hump.

The last thing is adding baffles and the appropriate breather attachments to the oil tank, which I will need some help with. Im thinking 1 or 2 baffles that span across the whole tank vertically separating the feed and return sides and have 6-8 holes around 1" each. As for breathers, I need one for the crank and one for the valve cover. Thoughts from the gurus?

[slikwilli420]

I would agree on your assessment about the top being used as the bottom. I have two clamps in very good shape and on will be machined to accept a new steering stem from Cycle X. I have drilled and tapped the stem for a 10mm bolt that will hold a thick steel "puck" from the underside that will sandwich the stem into the lower tree, basically eliminating reliance on the pinch bolt, but that will still be there simply to snugly clamp the stem but not provide any actual support. The hardware top and bottom will also be replaced with ARP bolts for looks and strength.

[slikwilli420]

For the electrical relocation project, I wanted to share what I came up with. You can see that I wanted to raise the panel as far up as I could without interfering with the seat subframe (Im 6'1" so I need legroom) that will be there shortly so as little of it hangs into the triangle as possible. For a guy who has all of a month of welding skill I think it will look great after some powedercoat and some finish work.

[slikwilli420]

Just finished getting the manifold plates cut for the Weber's at a local waterjet place. As soon as I can get the spigots machined they will be laser welded on and then the holes tapped for 8mm studs.

[slikwilli420]

So as a I bounce around this project working on whatever I feel like for the day, I come to rear axles and exhaust that I need some guidance on.

For the axle, I am using Voxonda's Dresda replica swingarm, and I need a longer axle. I have found some really nice deals on TGP shafting and thought about having the correct length piece threaded on both ends, one for a stationary nut and the other for a castle nut/pin. Is it easier/better to go this way or, as brandEn did on his build with a similar swingarm, and use an 80's Honda VFR axle, either stock length with spacers or have it cut down and rethreaded?

As for the exhaust, my bike came with a Kerker 4-1, where the flanges are on the exhaust permanently, so all I have on the head are studs. I am going with a vintage RC 4-1 that has no flanges with it, but the header ends are swaged slightly larger diameter, and have splits on either side. What flanges/attachments are the most appropriate? I would like to use period parts, but if there are new parts with a not-too-modern look, that would work as well.

Looking forward to thoughts.

[seanbarney41]

As for the exhaust, my bike came with a Kerker 4-1, where the flanges are on the exhaust permanently, so all I have on the head are studs. I am going with a vintage RC 4-1 that has no flanges with it, but the header ends are swaged slightly larger diameter, and have splits on either side. What flanges/attachments are the most appropriate? I would like to use period parts, but if there are new parts with a not-too-modern look, that would work as well.

Looking forward to thoughts.

sounds like you need the stock spigots and clamps, spigots bolt on to cylinder head via your existing studs or bolts (stock used crosshead screws!), header slips over spigots and then finned clamps tighten over the slip joint.  You will just need the spigots and clamps from a '76 or earlier engine.

[754]

If you thread each end of shafting you eliminate any welding or cracking problems, works well

[slikwilli420]

That's my plan Frank assuming I don't go with the VFR axle. Between that,  mounting the Lockheed caliper and rebuilding the Marzocchi strada socks I should be wrapped up on the rear end.

[slikwilli420]

On the rear end, I am still waiting to get the Marzocchi Strada bodies powdercoated, then they can go back together. I picked up a VFR axle in great shape that will work with the wider swingarm. I also have the caliper bracket for the rear that I just got back from the waterjet shop.

The front is coming along well too. The waterjet shop made the brackets for the front calipers in two pieces so I can play with spacing to the rotor. If you find pictures of Dholda CB750 endurance bikes, you will see my inspiration for the front.

Im also working on rearset brackets, which cam from the waterjet as well. These are similar in style to the ones brandEn has on his bike that FunJimmy made. I still need to cut the passenger triangles so they fit flush. I have also picked up some 1045 TGP shaft to make longer bolts for the brackets to bolt to.

Last update is the triple trees. I have been staring at the originals for a while and am really put off by the porosity of the aluminum and I thought that since Im trying my hand at CAD, I would draw some up. The pics are the two designs I like the best.

[seanbarney41]

those front brakes are like just wow

[Jerry Rxman Griffin aka MuthaF'er]

Got some cool #$%* going on! Keep the software. Maybe you can peddle some wares to us F'ers.

About your oil tank/fuel tank combo - what do you anticipate the heat from the oil doing for the gas and the rider? Roasted balls?

[SOHC4 Cafe Racer Fan]

Great job fabbing those brake brackets.  I have a pair of those AP calipers.  Would you consider sending me the waterjet specs for the brake brackets?  Or if you could cut me a pair, I'd gladly pay for them.

Don

[slikwilli420]

Sean,  she will be on the road soon,  hopefully for Gilmore in June and then maybe we can finally meet.

F'er, roasted balls is a concern. I plan on keeping it under control with stick on heat tile. The oil cooler should help as well.

Cafe racer,  send me a PM and we can discuss the brackets.

[slikwilli420]

Is this what I need to make my RC header work? This header has the tips swaged to a larger diameter for about and inch or so with a split down both sides so they flex.

http://www.ebay.com/itm/1974-HONDA-CB750-K4-CB-750-HM735-ENGINE-EXHAUST-HEADER-SPIGOTS-MANIFOLD-FLANGE-/351061267135?pt=Motorcycles_Parts_Accessories&hash=item51bce1d2bf&vxp=mtr#ht_1872wt_691

and

http://www.ebay.com/itm/HONDA-CB-750-FOUR-73-74-EXHAUST-FLANGES-COLLARS-CLAMPS-H214-1-/231188475961?pt=Motorcycles_Parts_Accessories&hash=item35d3e83039&vxp=mtr#ht_1857wt_691

[seanbarney41]

you got it