Anti dive/speedo

[Pat Conlon]

Hey David, I'd sure hate to have him do all this work only to use his oem 5/8" m/c and have his new brakes feel like shit, or when on the brakes, have the front forks collapse with those weak sauce oem '92 fork springs.

Hey Joe, it's not just the front rim, but All 3 components of the front assembly are lighter:

1)  '89-95 oem FJ 17" front rim uses a hollow 3 spoke design so it's lighter than the early cast 16" rim.
2)  '89-95 oem single face rotors are lighter than the early oem dual faced vented rotors, even better if you use eBay Arashi wave style rotors which are even lighter still.
3) The 120/70-17 radial tire is lighter than the 120/80-16 bias ply donut.

How much lighter?
Knew you would ask....thru the years we've weighed the rims/tires/rotors several times but I can't recall a specific number....I want to say 6 lbs lighter but not sure.
Someone will have to search.  It's jammy time for me...yawn.

One last thought...remember for every ounce of weight savings is equivalent to 24lbs when that tire is spinning at 100mph.

[Troyskie]

On seeing Pats post after my last reply, I would be remiss if I didn't pinch the scales from the house and weigh those pesky wheels seeing as I have all the combos mentioned (sort of).

FJ Owners disclaimer, these scales are cheap shit from Kmart and are NOT accurate (thanks China! and you lowest price wins master degree purchasing mongrels). The weights pictured are the most consistent measures (each wheel went on half a dozen times and I deleted most of the photos), but the piece of shit is not accurate (it was however, very cheap).

Anyhoo, here are the numbers, supported by photos. Also all the wheels had tyres (well worn), discs (I have no diarrhea I mean idea), and sprockets bla bla.

Wheel 1, 16" front (84-85?) with some massive after market discs....13.9kg (30.58lb)
Wheel 2, 17" front with oem discs....12.4kg (26.4lb)
Wheel 3, 16" rear 84-86(?), with after market disc....18.9kg (41.58lb)
Wheel 4, 16" rear 3 spoke, after market disc....16.4kg (36.08lb)
Wheel 5, 17" rear 17" FZR(?) 5.5", with wave disc (no idea of mfg), 14.7kg (32.34lb)

My only question is when will civvy US catch up to mil US and go metric? The performance difference between 16" and 17" is very clear (oh shit, I just realised I used antique, not current   language), I also just realised I'm using the Aussie version of Windows (Windaz) it has a 'Start you c@nt!' button .

I'm also an antique as I still call emojis 'smilies'...

[Pat Conlon]

Thanks Troy!

Back in 2010 I was working on Paul's '92 putting a new tire on the back while also doing my FJ so, seeing as though I had both wheels off at the same time why not weigh them to see the difference? Same POS bathroom scale.
Paul's 92 had the oem 16" 3 spoke rim/rotor/sprocket/150/80-16 tire = 41 lbs
My bike had the 17"x 5.5" Thunder Ace rim/wave rotor/sprocket and 180/55-17 tire = 36 lbs

I was close on the 16" vs 17" front wheel huh?

8 years ago, I measured a 5 lb difference in weight between the 1992 oem 3 spoke 16" FJ rear wheel/tire assembly and my 1997 YZF1000 17" wheel/tire assembly.
http://www.fjowners.com/index.php?topic=1885.msg14921#msg14921

Remember, the 3 spoke Yamaha rims were lighter than the early design FJ rims so the 5 lb difference would be even greater comparing my T-ace wheel/tire assembly to a early FJ 16" wheel/tire assembly.

I'll bet a jelly donut that if you compared a early FJ 16" front wheel/tire assembly (w/oem rotors) with a 17" FZR wheel/tire assembly (w/Ashai rotors) you will also save ~5 lbs in weight.

Is 5 lbs of weight savings really such a big deal?
It is when you are at kookaloo speed: 16oz x 5 = 80oz x 25 = 2,000 lbs spinning around @100 mph.
http://www.hardracing.com/Rims/WheelWeightInfo.htm

[Troyskie]

Very close mate!

[ryanschoebel]

One last thought...remember for every ounce of weight savings is equivalent to 24lbs when that tire is spinning at 100mph.

Hey Pat, in the interest of curiosity,could you elaborate on that? is it simply because of the centrifugal force? Or in what capacity is the weight multiplied?

[ryanschoebel]

centrifugal force?

Or centripital, rather.

[FJmonkey]

Ryan, think gyroscope... https://science.howstuffworks.com/gyroscope1.htm

[Pat Conlon]

Hi Ryan, yep, as Mark said, think of a gyroscope....did they have those toys when you were young?

Lots of good stuff on the 'net on the advantages of light weight motorcycle wheels on static and dynamic loads

[Alf]

Wheel 1, 16" front (84-85?) with some massive after market discs....13.9kg (30.58lb)
Wheel 2, 17" front with oem discs....12.4kg (26.4lb)
Wheel 3, 16" rear 84-86(?), with after market disc....18.9kg (41.58lb)
Wheel 4, 16" rear 3 spoke, after market disc....16.4kg (36.08lb)
Wheel 5, 17" rear 17" FZR(?) 5.5", with wave disc (no idea of mfg), 14.7kg (32.34lb)

I'm having my own data. These are the ones collected so far and there are significant differences with yours, I don't know why

Front 16" complete 12,8 kg    (Spanish mag MOTOCICLISMO weighted 12,6 kg) STD discs
       17" complete 13,1 kg (FZR 1000 3,5") STD discs

Rear rim only, without sprocket carrier & disc        1TX/1100 16"  6,1 kg
  (the same parts for the 3 of them)                   3CV         16"  6,4 kg (it was really a surprise!)
                                                                     FZR 1000 18"   7,6 kg (even more surprised)


I have still to weight again my complete GSXR 5,5x17 rim fitted in my 3CV (+-12 kg) and the complete 16" STD rear rim in my 1TX (MOTOCICLISMO 16,3 kg)

So with OE rims, 1100s and 1200 1TX have less non-suspended weight than with FZR rims

[Troyskie]

Alf, my scales are just cheap ones. I did repeat weigh them to see if the same number came up, but still the load cell in these cheap scales is unlikely to be accurate.

[Alf]

Well, mine are not too accurate, but the comparative with the mag gives me a little reliability

Its true that comparing 2 FJs with FZR 17" rim one of them, and with the GSXR rim the other you can feel the difference between suspended weight: the SACS rim mounted FJ feels shorter and more flickable than the FZR fitted bike