Author Topic: CB 750 Diet Thread  (Read 2149 times)

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Offline 754

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CB 750 Diet Thread
« on: March 25, 2009, 07:51:07 PM »
Just thinking, we could list things that bolt on, or are minor mods that save weight.

Front hubs for wire wheels.

77/78 definitely look lighter, cant tell how much, but they will save weight.

Earlier hubs can get some weight carved off, betweeen the bolts and by turning the centre fins off on a lathe (just did one)

Also by intalling helicoils & studs to fasten disc, can save a bit  more.
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My next bike will be a ..ANFOB.....

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73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Online Alan F.

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Re: CB 750 Diet Thread
« Reply #1 on: March 25, 2009, 08:28:00 PM »
It depends how far from stock you want to stray.  Any nonstructural part of the bike that was originally steel could be fashioned from aluminum or even titanium.  The aluminum D.I.D. wheels from the 750A model come to mind first, JT Sprockets has aluminum sprockets available, most modern bikes use hollow axles, rearsets are always lighter than stock controls, lighter handlebars are certainly out there, some of the headlight setups that use H-4 bulbs are plastic as opposed to the heavy sealed beams, Smaller batteries or gel batteries, modern handlebar switch pods are often plastic, aluminum swingarms are out there, 520 chain conversions will lose a few lbs, thin walled aluminum oiltanks, 4:1 headers as opposed to 4:4 pipes saves a ton, mini-turn signals will save some weight, ditch the fork ears and find aluminum headlight bolts, plastic or fiberglass fenders, leave the toolkit at home, ditch the starter motor, get a lighter aluminum kickstart lever, cut off the passenger peg mounts, go with a plastic chainguard if you have the steel one, aluminum spacers for the rear wheel, a lighter brake pedal, there's more but I can't think of any right now. 
One would think you could drop lots of weight just by replacing one part with a lighter part, then there are parts that can be removed, then there are lots of guys who'll drill everything full of holes to reduce weight even further. 

I wonder how much weight you actually could drop?  15-20 percent? 

Offline 754

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Re: CB 750 Diet Thread
« Reply #2 on: March 25, 2009, 08:34:29 PM »
I think my iceracer was around 425 or 450.

Mostly factory parts (except pipes), but lots deleted.

 There is some stuff now though, that will shed pounds, ie 2 77/78 rotors weigh about what the old single did, even drilled..
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

fuzzybutt

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Re: CB 750 Diet Thread
« Reply #3 on: March 25, 2009, 09:11:24 PM »
the aluminium sprockets also have the added benefit of much less parasitic losses. they last just as long as steel too. at least in my experience they do

Offline 754

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Re: CB 750 Diet Thread
« Reply #4 on: March 28, 2011, 08:23:10 PM »
Ok here is more;

 Got an aluminum 51 T sprocket for 750 rear, no lightening holes. Stock about 4 lbs, this weighs about 2, but I think I can carve another pound or close to it , out of the sprocket
 That is 3 pounds you dont have to wind up, and move with the suspension.

Chainguard.. stock is I think 2 lbs. Started building an alloy one today, think I can get to around 350 grams. That should help
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline seanbarney41

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Re: CB 750 Diet Thread
« Reply #5 on: March 28, 2011, 08:44:19 PM »
This is a good thread...more please...this clunky, overbuilt seat bracket really lost a lot of weight when it met up with the drill press.  I was surprised.
If it works good, it looks good...

Offline scottly

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Re: CB 750 Diet Thread
« Reply #6 on: March 28, 2011, 09:41:17 PM »
I smoothed and polished the stationary pad half of a late-model brake caliper today, (thanks Frank!) and knocked off 2 grams! ;D
The thinner Yamaha discs I'm using on the front are about 2 pounds lighter each than the stock discs, and while they are already slotted, could be drilled some to further reduce weight.
My aluminum sprocket had some lightening holes already, but I added some more years ago. I didn't have an accurate scale at the time, so I don't know how much weight was removed; I guess I could calculate it...   
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Offline 754

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Re: CB 750 Diet Thread
« Reply #7 on: March 28, 2011, 09:49:32 PM »
 Cut windows out of the sprocket, keaving spokes to hold it, takes more weight off..

 Are you under the big 4 yet??

 We weighed a lightened spun Mitchell wheel (front) with tire on it but no bearing plates or inner spacer.. came in around 13 lbs..

 i use a fishing scale and a gram scale for stuff under a 1.5 lbs..
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline Silverback

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Re: CB 750 Diet Thread
« Reply #8 on: March 28, 2011, 09:53:52 PM »
I think the most obvious components are the wheels, battery, starter, rear stand, exhaust, seat, fenders, tank(switch to aluminum) and copious amounts of titanium/aluminum nuts and bolts.

I have a box with all of the stuff I have removed/replaced from my 78F. It's certainly not light! I plan on weighing the bike after it's finished for #$%*s and giggles.
Chris
"It's hard to define soul. You get it in art. You get it in music, and occasionally you get it in machinery."
78 CB750F racer
78 CB750F stock
75 CB750K Baby Blue Sold (She was a great bike!)
71 CB750K (rusty rod)
77 cb550F Sold :(  Bought it Back :)
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Offline scottly

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Re: CB 750 Diet Thread
« Reply #9 on: March 28, 2011, 10:04:20 PM »
I have been using a triple-beam scale, that can weigh up to 2.6 kilos with auxiliary weights.
Btw, I weighed an inner-tube; it was not anywhere near as heavy as I previously thought. Still anxiously waiting to weigh the bike after I get it put back together. There are other things I would like to do, like lighter foot controls, but I have to make sure the bike is up and running for the relay first.
Don't fix it if it ain't broke!
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Offline fatmatt650

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Re: CB 750 Diet Thread
« Reply #10 on: March 28, 2011, 10:06:13 PM »
I've been cutting weight off a 76 cb750F and weighting the new and old parts and this is a pretty complete list of what I've got so far.

f. fender - 5 lbs     switched to Dunstall fiberglass (no brace)
seat - 10 lbs     switched to Carpy duckbill solo seat
starter - 5 lbs     removed
centerstand - 5 lbs     removed
horn - .75 lbs     removed
f. wheel - 2.3 lbs     switched for Goldwing spoked  w/ alloy rim
handlebar - 1 lbs     switched for clip-ons
muffler plate - 1 lbs     removed
turn signals - 2 lbs     switched for little aftermarket ones
exhaust - 10 lbs     switched for O.G. Kerker w/ shortened muffler
42.05 lbs
So much to do, so little time.

Offline scottly

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Re: CB 750 Diet Thread
« Reply #11 on: March 28, 2011, 10:25:48 PM »
I have it written down somewhere; I think the starter clutch and gears were close to 3 pounds, so about 8 pounds total with the motor and wiring?
Don't fix it if it ain't broke!
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Offline 754

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Re: CB 750 Diet Thread
« Reply #12 on: March 28, 2011, 10:40:56 PM »
Did the starter wt include its heavy cable ?
 Now add the solenoid, and about 5 or more lbs, now that you can run a 5.5A  battery or less, plus a smaller battery tray if you feel like making one.
 more like 15 lbs or so..


 then take 2 or more off the charging rotor.. adds up after a bit
« Last Edit: March 28, 2011, 10:44:40 PM by 754 »
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline scottly

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Re: CB 750 Diet Thread
« Reply #13 on: March 28, 2011, 10:59:23 PM »
After I ditched the starter, I went to a 3lb battery. My new high tech battery is less than a pound! I can shed some weight from the alum batt box I made for the 3lb, plus I bought a couple of bridge rectifiers that should be lighter than the stock rect, but I haven't weighed either yet.
Don't fix it if it ain't broke!
Helmets save brains. Always wear one and ride like everyone is trying to kill you....

Offline Gordon

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Re: CB 750 Diet Thread
« Reply #14 on: March 29, 2011, 12:10:49 AM »
I managed to drop about ten pounds off both my 750 and 550 in the past few weeks by adding 65 pounds of weight to my bicycle.  In the form of my two kids and the kid-trailer. ;)  By taking them to daycare and to various playgrounds multiple times per week, I've made both of my sohc4's more responsive! :)