Topic: 73 CB750

[Gizmo]

Hi everybody,
I was hoping to get some advice / opinions from the wealth of knowledge that is this forum. To date I've dismantled the entire bike aside from the bottom end of the engine (6000miles on it, didn't think it warranted pulling it apart based on the low amounts of ware I've been seeing elsewhere). I've ported and polished the head. Installed and bored out new valve guides. Lapped all of the valves. Opened the cylinders up to 836cc (Replacing one sleeve in the process with a small crack developing at its base). Installed a new clutch pack.

My vision is to have a naked bike look with either a brat style seat, or cafe racer fairing (which will house my oil tank). The brakes, fork, and frame geometry will stay stock at the moment because that is not in my budget at the moment. The stock oil tank will be replaced, and electrical components relocated. An 836cc kit is being installed, but with the stock cam at the moment (though a frame splice kit is being installed for ease of access should i decide to install it latter) The stock air box will be replaced (velocity stacks or filters? haven't decided yet)

I've purchased and intend to install; all new gaskets, new engine hardware, new timing chain and guide, 836cc pistons, dyna 2000 electronic ignition, new regulator/rectifier, frame splice kit (gordon style) and will be making my own wiring harness.

Rather long winded, my apologies.  The questions i have for the members at the moment relate to the frame. With the measure twice cut once mentality in play, i was wondering what the members think of; removing the centre stand entirely.

Any suggestions for the frame splice kit, my notion is to drill a small hole in the original tubing and while holding a bubble level across the splice halves "rose bud weld the splices in place prior to laying a nice bead around them.

This bike is for me alone, no passenger foot rests required. But is it fool hardy to cut them off? Do they ever serve a purpose for a mounting location for a future brake reservoir or a nice place to bolt or weld rear-sets on to?

Thanks for taking the time to read, and offer up any advice!
Gizmo

[Gizmo]

Forgot a pic... More to come when i make it home and have access to the point and shoot camera.

[Tews19]

Hit up member "754". Frank is in Canada as well and has a weld less frame kit.

[Stoli]

First off, thanks for the compliments on my build threads. Much appreciated!

I can't address your frame kit questions but regarding the center stand, I find it invaluable for things like oil changes and tweaks that require you to get the rear and/or front wheel off the ground. Some bike lifts accomplish that but those typically require you to remove the exhaust. I don't keep the center stand on my bikes but I do keep the mounting brackets on them and when I need it I just put the stand on and insert the pin. Takes about 20 seconds to install and remove.

Rearset mounts are a tough call. Custom brackets welded on look the best. If I had the proper welding tools and skill, I'd go that route. The only use for rear peg brackets on a one up bike would be rearset mounts and exhaust hangers so figure out those two things and if you don't need them, chop'm off. Unless you have really long legs, the rear peg brackets are probably too far back for rearset mounts.

[754]

 I will have some weld less frame kits, ready in a couple days. PM me your email, i can send pictures. Where are you located?

[Stoli]

Sorry for the quick hijack, but is there a link to pics and/or information about your weldless frame kit? Cost?

[Gizmo]

Thanks for the input guys. I've actually already got the frame splice kit. The welding doesn't scare me so I've purchased one of Cycle X's plug style kits. It may be OCD but i preferred this kit style to prevent moisture and rust from developing inside the frame. Some of the other kits I've seen cut the top tubes and simply slide a sheath over top of the frame. Probably not a big deal, I just appreciated the elegance of the Cycle X style kit.

Stoli. That is pretty solid advice about the centre stand. For the moment I will leave the pivot point on the bike, and only after settling on an exhaust set-up which may or may not interfere with a lift will i commit to chopping it off.

Can't wait to get home to tear into it again!

[754]

Here is the kit quick easy installation.
 Cut, deburr, drill, 4 holes for the two straps.. And put back together.
If your paint is real thick, may have to sand some off.

[Gizmo]

To achieve a naked bike look in the rear frame where are people locating their oil tanks these days?

[ekpent]

Got any more pictures of the before, looked like a nice clean survivor. Only 6,000 original miles ?

[Restoration Fan]

To achieve a naked bike look in the rear frame where are people locating their oil tanks these days?

The coolest one I've seen lately on a cafe build had it inside the "hump" that's built at the rear of the seat.  I've also seen that space used for the battery box on another build.

[SOHC4 Cafe Racer Fan]

Speed Merchant and my friend Ian Halcott both build oil tanks into their metal seats (both aluminum and steel).

Ian also builds oil tank/fenders.  If painted black, they practically disappear.

[Gizmo]

Current frame status

[Gizmo]

I've cut and fit the frame splice kit and brat hoop but have held off on welding it till i sort out what my finished oil tank, and fuel tank configuration will be. As well the passenger foot peg supports are now gone.

[Gizmo]

Todays project included installing and adjusting the valve train, and rebuilding the oil pump.

[Gizmo]

Thanks for the oil tank suggestions! There is some gorgeous craftsmanship in those fender styled tanks!

[Gizmo]

Carb suggestions please!

I am looking for a good baseline position to begin with;
My 73  has-
-been bored out to 836cc
-stock cam
-mild porting
-will be running a 4 into 1 exhaust
-will be running pod filters.
-my home town has an elevation of around 350m or 1150 feet


The carb rebuild kit that i have purchased comes with 110 mains and 40 idles. and my stock needle came with the circle mounted 4th from the top.

can i drill out the original main and idle jets to a larger size (If so which drill sizes correspond to the appropriate jet positions)? or is this a fools errand? (am i being cheap? do i need to buy a range of jet sizes to get this dialled in?)

[Davez134]

I have a very similar setup to yours. 836cc, stock cam, K&N pod filters, MotoGP 4-1 exhaust, just under 2000ft. elevation. I have 130 mains in there, 40 idles, clip 4th from top. Runs perfect. I did alot of trial/error, plug chops under different throttle positions. Don't bother drilling out mains, as it is hard enough getting it just right with pods. Get some different (bigger) sizes and dial them in. If you already know what too rich and too lean feel like you will have it done fairly quickly.

[Gizmo]

Thanks very much!!!! always nice when someone takes the guess work out of it. I feel like i owe you a beer or two.

[Gizmo]

tank and seat mock up.

[Restoration Fan]

Question for you cafe guys:  don't those thin seats like that get really uncomfortable, really quick?

[SOHC4 Cafe Racer Fan]

Gizmo,

It looks like your tank is fiberglass. Make sure you epoxy line it with Caswell's or something similar - and even then keep an eye on it for leaks. Ethanol is murder on the resin bonding the fiberglass together.

[calj737]

If it is fiberglass, definitely required to use Caswell. RedKote is not fiberglass compatible.

[Retro Rocket]

If it is fiberglass, definitely required to use Caswell. RedKote is not fiberglass compatible.

Also, there are some good fuel resistant epoxies around.....

[Gizmo]

a few photo updates