1982 CB750F... The resto-not

Maritime

Active Member
Re: 1982 CB750F Resto-mod. At least that's the current plan.

Woot there it is. Good deal Jim. Looks like a full on project can commence now.
 

The Jimbonaut

Active Member
1982 CB750F Resto-mod. At least that's the current plan.

Got all the scaffolding off the back of the bike, here's what I got up for grabs -

Front fairing -



Crash bars -


Two floorboards -



Forward controls w/floorboards -


Saddlebags & bracket (maybe off a Rebel?) -



Sissy bar (off a Rebel) -


Saddlebags & sissy bar may be spoken for - if it doesn't work out then like everything else it's all free, just cover postage (from here in Canada). Lemme know =)

Picked up a tank today, it's taken one for the team but it should pop out (any suggestions on how to do that would be gratefully received) but inside is spotless, no rust or varnish at all. And that means no MEK, and that's a wonderful thing.



It's a K model tank and that's fine by me. Although the bike is an F, I prefer the styling and lines on the K tank and love the gold pinstripe. Got a colour scheme in mind, and I'll definitely be incorporating that gold pinstripe into the design.



Bike-like.

And here's what I pulled out of the air filter housing...



Gotta hand it to the little guy, that looked snug. If I was a rodent shivering away in a Quebec winter I'd've made my crib as comfy as possible too. Sorry fella, you're evicted.

Also checked compression today -
Cyl #1 - 165psi
Cyl #2 - 170psi
Cyl #3 - 165psi
Cyl #4 - 165psi

Pretty damn good. I mean, shit - factory is 170psi +/- 14psi according to Clymers. This thing's barely lost anything in 35 years. Gotta hand it to those Japanese, they sure know how to build an engine.
 

pidjones

Active Member
Re: 1982 CB750F Resto-mod. At least that's the current plan.

I've read that hot glue on a dowel rod can do wonders for popping such dents. No experience at it, however.
 

adventurco

Nick Ol' Eye
DTT BOTM WINNER
Re: 1982 CB750F Resto-mod. At least that's the current plan.

I've tried the hot glue but I think the bigger the surface you glue to it the better. Like a drink bottle with a bigger 1" cap, I think cbrianroll posted a pic of that in Hurco's TW200 thread now that I think of it.

Also heard of people using a sphygmomanometer inside the tank and inflating it, or baking soda and vinegar to pressurize the tank and pop out the dents that way (careful not to bust the seams)
 

The Jimbonaut

Active Member
Re: 1982 CB750F Resto-mod. At least that's the current plan.

Well the orderly line of people queuing up by my garage door for a beat-up 80's era burgundy front fairing with missing indicator never happened. Stunned silence? I know I know. I couldn't believe it either.

Pulled the carbs out again now I know it fires, bench synched them, cleaned out the airbox and filter. I've realized it's a hell of a lot easier to install (and remove) these carbs by only attaching one accelerator cable (the pull one, not the push one). Of course both should be attached but I'm wondering if it's a complete no-no to leave the push cable off - temporarily. I basically need to get this bike through a safety exam (hmm, ironic) and then will be pulling everything apart again for the build. Bad idea? If that cable snaps then I'll answer my own question in dramatic fashion I guess...
 

The Jimbonaut

Active Member
Re: 1982 CB750F Resto-mod. At least that's the current plan.

Can anyone tell me if these carbs are stock? Looking at Clymers it says (if I remember correctly) that the CB750F has either VB 42 A, B or C. These are 42 E. Anyone know what the difference is?

 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
Re: 1982 CB750F Resto-mod. At least that's the current plan.

82 CB750F should be VB42AG
 

The Jimbonaut

Active Member
Re: 1982 CB750F Resto-mod. At least that's the current plan.

Cheers Irk. Any idea what the differences between the carbs are?


Sent from my iPhone using DO THE TON
 

The Jimbonaut

Active Member
Re: 1982 CB750F Resto-mod. At least that's the current plan.

So that’s what that thing’s called. Learn something new every day


Sent from my iPhone using DO THE TON
 

adventurco

Nick Ol' Eye
DTT BOTM WINNER
Re: 1982 CB750F Resto-mod. At least that's the current plan.

The Jimbonaut said:
So that’s what that thing’s called. Learn something new every day


Sent from my iPhone using DO THE TON
I only know the name from looking it up for popping dents on a motorcycle tank ;D
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
Re: 1982 CB750F Resto-mod. At least that's the current plan.

The Jimbonaut said:
Cheers Irk. Any idea what the differences between the carbs are?


Sent from my iPhone using DO THE TON
Hard to say. I've never see anything about your particular E carbs. They might be Euro spec or something, but all the VB42 carbs (in the US) are jetted the same and share common specs on paper:

3 Jet Vacuum Slide:

EPA Spec (US), Hidden Emulsion Type Idle Mixture Screw, Non-Replaceable Slow Speed Jet (Some Models) Non-Adjustable Jet Needle (All Models) Air Cut Valves (All Models), Twin Sequentially Functioning Main Jets (68/102), Slow Speed/Pilot Jet (35), Accelerator Pump (All Models)
 

The Jimbonaut

Active Member
Re: 1982 CB750F Resto-mod. At least that's the current plan.

Cheers man - from what I've read the number after VB (in this case 42) refers to the size of the venturi. Jets-wise, these carbs have been fitted with 68 primary and 100 secondary. But the Clymers indicates the F should have 102 I think.

"Dabbled with" definitely applies to this bike.
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
Re: 1982 CB750F Resto-mod. At least that's the current plan.

The Jimbonaut said:
Cheers man - from what I've read the number after VB (in this case 42) refers to the size of the venturi. Jets-wise, these carbs have been fitted with 68 primary and 100 secondary. But the Clymers indicates the F should have 102 I think.

"Dabbled with" definitely applies to this bike.
That's correct. It's always Venturi size at the slide. And definitely should have a 68/102 in stock form.
 

The Jimbonaut

Active Member
Re: 1982 CB750F Resto-mod. At least that's the current plan.

The bike has a 4 into 1 Kerker exhaust - may that be why the jetting has been adjusted?
 

The Jimbonaut

Active Member
Re: 1982 CB750F Resto-mod. At least that's the current plan.

Carb hose question - when I pulled the carbs, both hose A and hose B were connected to the carb body at one end but not the other -



here's another shot -



But on my other CB750 there's only one hose that's connected to both ports on the carb. So I did the same with this, ditched one tube and looped the other -



Is that correct?

Hooked up the carbs, tank, airbox again, fired it up - seems to idle ok but as soon as I crack the throttle the revs stay high. I checked all the boots to see if there was a vacuum leak but they seem ok, and the throttle cable isn't binding. Any ideas what could be causing this?
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
Re: 1982 CB750F Resto-mod. At least that's the current plan.

That's your automatic fuel valve.



The tube in your fingers is an air line. The tube in your thumb is a vacuum line. Your high idle sounds like maybe the carb is running out of fuel and going lean.
 

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