Topic: New Member...Question about Weight Savings

[edosm]

Hello Everyone,
 I'm brand new to the board..and just picked up a 1975 CB750F...It's my first Classic Bike..and yep it's a fixer upper...

I'd like to turn it into a cafe racer. The bikes in pieces for now...but I'd like to lighten it up as much a possible, while I put it slowly back together.

What are the best things to get rid of for weight savings...and or replace. I figure the seat, center stand...what else. Is it possible to get it down to 400lb or less?
By the way..How much does that engine weigh.

Thanks so much...and I look forward to reading thos Board Daily
Mike

[Tim.]

Wow - don't think you'll make 400 - that's over 100 off the stock weight.  Remember rotating mass is more critical, so go with alloy rims, drilled rotors etc.

Also the stock muffler is mega-heavy.  Lose the fenders.

Bottom line is don't put anything on it that doesn't make it move.  Then worry about making it legal to 10 minutes while you register it 

[hondachopproject]

Welcome and good luck on your fixer upper  ,
Well first some weight can be deducted if you decide to remove some of the frame under seat.
If you go only kick start (some will advise against) you can pitch starter and that whole system.
rear foot pegs.
smaller seat
Again Good Luck,
Lee

[Roach Carver]

Welcome, Drill holes in everything, only run 2 quarts of oil and fill the gas tank half full. also instead of boots wear flip flops. just a thought.

[hondachopproject]

wear flip flops. just a thought.

Maybe tighty whites instead of boxers, 71cb750?
Maybe a thong?
oh yeah, and only drink light beer, when out for a "ride".

[BobbyR]

This may also help

[Bob Wessner]

By the way..How much does that engine weigh.

The 750 engine/tranny package goes approximately 170 lbs.

[Roach Carver]

here is some serious advice. 4-1 header should be lighter. If you are making a cafe bike drill holes in the shifter. holes in the kick start or ditch it all together. digital speedo and mini tach or no tach. fiberglass seat pan with pad. as previously stated, if it is not necessary to make it go and roll, leave it off.

[liaudio]

Honestly, don't worry about any of that at first.  Just get the bike running and dialed in. (ie. running, idling, steering and braking properly.)

Under 400lbs? No F'ing way. 

IMO, keep the electric start.

[Terry in Australia]

here is some serious advice. 4-1 header should be lighter. If you are making a cafe bike drill holes in the shifter. holes in the kick start or ditch it all together. digital speedo and mini tach or no tach. fiberglass seat pan with pad. as previously stated, if it is not necessary to make it go and roll, leave it off.

I think you'll be taking that kick-starter off pretty soon after you drill a few holes in it, particularly after you try to use it for the first time and it bends like a banana, ha ha! 

[ProTeal55]

I agree with LIAUDIO, get the bike running first, then start to remove/modify/destroy/customize/etc...

Things to remove:
1. Fenders (both front & rear)
2. Center stand
3. Stock turn signals (replace with smaller/lighter aftermarket ones - if at all)
4. Stock headlight ears (replace with smaller/lighter aftermarket ones)
5. Replace stock seat with fiberglass "cafe" style with minimum padding4 yer butt
6. Drill some holes in places, but don't get too crazy (lots of places to drill holes )
7. Cross drill rotor(s)
8. Remove stock airbox and go with alum. stacks
9. Ditch the electric starter (I wouldn't, but it is weight)
10. Remove the brace under the seat (I just did , and it weighs a decent amount)
11. Run smaller gauges (or none at all)
12. Run the smallest bars possible (smaller = lighter)
13. Aluminum wheels
14. Ditch/remove all wiring not needed to run bike (like turn signal buzzers and crap like that)
15. Do some research and get the smallest/lightest battery you can that will work on the bike
16. Go with a light 4 into 1 exhaust with a small "cannon" or muffler

I think you'll be taking that kick-starter off pretty soon after you drill a few holes in it, particularly after you try to use it for the first time and it bends like a banana, ha ha!

Terry ,
I have had my drilled kickstarter on my bike this entire season, and haven't had an issue with it yet.
Guess I have been lucky...

[nickjtc]

In all seriousness, for a minute. Didn't I read somewhere that for the average western person + bike, the simplest and cheapest way of removing weight would be for the person to go on a diet....??

[Sam Green Racing]

Tintin/Liaudio, I have a little bad news for you both.....396lbs (180kg)..and you can get one lighter.
When I put the CR together for Chris, I built it to the specification he asked for.
Had I been asked to build the bike as light as possible, I could get quite a few more lbs off.
It just depends on what you want the bike to look like, also how much you want to spend.
Sorry for pissing on your fireworks.

Sam.

[Gordon]

Is that 396 lbs. wet or dry weight?

[Sam Green Racing]

It would have had oil in it Gordon, not sure about fuel or how much if any.

Sam.

[Gordon]

That's pretty impressive!  Were you running helium in the tires?

[edosm]

Awsome!..thanks for the replys... I will loook into everyones advice and take it a day at a time..

Oh the rims are not Spoked...but I believe the aluminium ones that came with the 750F...would these be lighter or not...

What could I DRILL into without weaking the frame...?

What other Honda Factory Rims could I swap over..without any hassle...that are know to be lighter?

Are there Smaller Gas Tanks that share the same mounting configuration?

Who sellls smaller Speedo and Tach....that thread into OEM cable

Thanks again...
Mike

[Tim.]

When an expert bike mechanic/builder/engineer/scientist or whatever the proper nomenclature is these days builds a CR750 with the express design intent to make it as light as possible and gets it 4 pounds below 400, I stand by my earlier statement that a mere mortal is unlikely to make the same target.  I have NO experience to back up my statement - it was purely a gut feel, and it turns out I was pretty darn right that it's near impossible to make a 750 weigh less than 400 pounds.

So piss on my parade or in my cornflakes all you like 

[Tim.]

Awsome!..thanks for the replys... I will loook into everyones advice and take it a day at a time..

Oh the rims are not Spoked...but I believe the aluminium ones that came with the 750F...would these be lighter or not...

What could I DRILL into without weaking the frame...?

What other Honda Factory Rims could I swap over..without any hassle...that are know to be lighter?

Are there Smaller Gas Tanks that share the same mounting configuration?

Who sellls smaller Speedo and Tach....that thread into OEM cable

Thanks again...
Mike

Just don't drill holes in the gas tank - I tried that once.  Didn't work out so well.

[cb650]

One of my 650s is 400 lbs.   With me helmet leathers and gas we go over the scales at 600.
And I cant get rid of the electric starter.




                 Terry

[Terry in Australia]

Awsome!..thanks for the replys... I will loook into everyones advice and take it a day at a time..

Oh the rims are not Spoked...but I believe the aluminium ones that came with the 750F...would these be lighter or not...

What could I DRILL into without weaking the frame...?

What other Honda Factory Rims could I swap over..without any hassle...that are know to be lighter?

Are there Smaller Gas Tanks that share the same mounting configuration?

Who sellls smaller Speedo and Tach....that thread into OEM cable

Thanks again...
Mike

Alloy 1970's era mags (not comstars) weigh more than OEM steel wheels, the CBX comstars were all alloy and feather-light (as opposed to the CB750F2 SOHC comstars that had steel "spokes") but there was some concern that the rivets would get loose under some stresses. I've got one in my garage though, and it is really, really light.

I wouldn't drill into any frame sections, and personally don't see much value in drilling things like the kick starter unless your rings are stuffed and your lack of compression is such that you won't bend your kicker, but drilling your discs is a good idea though, for both weight savings, better braking performance in the wet, and less "fade" due to increased cooling.

The CB450 tank will fit your 750 with a few minor mods, and actually looks good, look at some of the after-market suppliers for smaller speedo's and tachs, and of course a 4 into 1 pipe will weigh a fair bit less than your OEM pipes, if you're still lucky enough to have them. Cheers, Terry.

[aptech77]

Ditch starter and gearing for starter in trans. ( less spinning mass) more power/less weight.
replace fenders with fiber fender or none.
cut down seat.
chop rear section down.
Lighter wheels.
remove center stand.
airbox go bye bye. Use pod filter.
remove all excess weight were ever you can. Cut everything off.
  

[Rhonda750F]

400lbs was my goal but but I reality set in.   
Here are a few more items I got rid of.
 
- Stock Handlebars, ditch em get clips, club, or drag bars. Smaller = less weight.
- Chaingaurd, thats a heavy piece of steel. Remove at your own risk!
- Toolbox and Crappy plastic fender.
- All the grab bars around the ass end that mate up to the top of the shocks.
- The mounting plate for the brake light, fab your own.
- The metal bracket that holds all the carb drain tubes and breathers.
- Even the footpegs can loose some weight cut the rubber sleeve off it and take off the weights at the
  end.  They end up looking like regular spotbike pegs.
- Either lose the fat brake pedal and replace or chop it up.
- Cut off misc. brackets on frame that no longer serve a purpose.
- And chop everything that you think needs a trim (seat, front fender, frame,etc.)

But hell if it doesn't make you go, stop, or turn, better or faster loose it.
Good luck.

[nickjtc]

All this talk about weight savings reminds me of a guy in Scotland, in the late '70s, who was fanatical about making his Triumph Trident as light as possible. I haven't got the mag article (in the old Bike magazine) anymore, unfortunately. He would get any parts he could made out of lighter material (I guess money was no option) and even went to the extent of calipering the windshield options (it was a race bike) to get the one that was the thinnest, just to save a few grams.

He ended up with a bike that was significantly lighter than stock.

[Bob Wessner]

He ended up with a bike that was significantly lighter than stock.

Presumably his wallet also.