Saving weight on FZR400 and possibly 600

[Freestyle72]

Ok so I started this thread because I am building a 400 and I would like for it to be 350lbs wet. Now that I have the bike sitting in front of me it feels really heavy compared to my 05 ZX6R 636.

So I am dedicating this thread to places that weight can be saved on the 400. I will post up the weights everything I swap on here and keep weighing my bike everytime I do a mod.

So far what I have for the bike is as follows.

96-99 SRAD GSXR750 Swingarm with shock linkage, axle, pivot bolt, brake caliper, and caliper arm weighs exactly 10kg or 22lbs

The 03 GSXR600 rear wheel 5.5"X17 with a dunlop tire, cush, sprocket and rotor on there wieghs 14.8kg or 32.5lbs

05 GSXR600 front end with calipers, damper, controls, Everything on the front end except wheel is 15.6kg or 34.3lbs

06 R6 subframe 1.8kg or 3.97 lbs (the 08 R6 subframe is 450g lighter or roughly 1lb)

Fo rthe R6 subframe I am having an aluminum shock mount made up as well because the stock steel one looks like a boat anchor.
I think with that made the total weight of the subframe will be 4lbs for subframe and 3 for shockmount, we'll see.

Once I start pulling parts off my bike for the swaps I'll weigh the stuff coming off to get an idea of the deltas. I know I will probably be gaining some weight with the swing arm and the big gsxr rear wheel, but I am willing to accept that. Besides I may switch to a gsxr600 swingarm which doesn't have all the bracing and may be a bit lighter than the 750 one I have.

Please feel free to add in weights of various mods you have.

[Fartblood]

Weight is a funny thing. Back in the day, the FZR600 was 181kg dry weight.

Today dry weight not only excludes fuel and fluids, it also excludes tyres and battery as well, so makaing comparisons from 20 year old figures against those for its year old equivalent are meaningless. You'd need both bikes in your hands to weigh them individually and make a direct comparison.

And part for part that's not a bad thin do do either - weigh them. But be cautious. Lighter may not mean better, or not as stiff, or deficient in some other way. For example, I acquired an FZR400 frame for my rebuild, and while it's lighter than the 600's steel jobbie, there's no way in hell that it's stiffer than the heavily fabricated 600 job.

Think about all areas of a components performance, not just it's mass...then remember that a pound of unspring weight is worth 3 to 5 pounds of unsprung lard when it comes to improving handling.

[thatkid]

Lighter may not mean better, or not as stiff, or deficient in some other way. For example, I acquired an FZR400 frame for my rebuild, and while it's lighter than the 600's steel jobbie, there's no way in hell that it's stiffer than the heavily fabricated 600 job.

I'd beg to differ on that. They are both strong enough to do their job. Steel is far cheaper than aluminum so it gets used more often when the bottom line is a concern. Both frames are built in a similar manner although the 400 frame can be built much lighter because it doesn't need to be full boxed like the 600 frame. Aircraft grade aluminum is a very stiff aluminum capable of withstanding tremendous force.

The 400 frame is a track proven frame for a reason. It's stiff enough to handle the forces that racing puts on it. I don't have formula's to prove my claims, but I have both frame and work with steel and aluminum and can say from hands on experience that aluminum is easily superior to steel in weight and stiffness.

The 600 frame is probably an A36 or 1018 mild steel. Yield strength of A36 is 36k psi. 1018 is a bit better at 53k psi but my guess is the frames are made with A36 as it's hot rolled and cheaper.

Now, 6061 is your most common aluminum used and it's yield strength is 40k psi. I'm not sure what specific aluminum is used in the 400 frame but it'll hold it's own against the steel frame of a 600.

[Fartblood]

I've had both held in the vice by the headstock, and the effort required to get visible deflection on the ally frame is much less than for the steel.

The steal is a cheaper material, but heavier. However, it also has better ductility so is less prone to damage or age/stress/vibration releated failure.

To my mind though, the biggest problem for the steel FZR frame is it's complex fabrication and the time, tooling and expense required to manufacture it. The 400 is a far simpler structue and probably a relative breeze to assemble. The design of the steel is very clever, especially around the lower headsock region, but looking at both it presents a helluva lot to work to construct compared to itaks alloy sibling, and I think that's what killed it stonbe dead. Today cast and extruded frame sections are the norm for alloy, but such techniques don't work well with steel, and to manually fabricate or hydroform steel to a similar design is relatively labour intensive.

[yamaha_george]

TK & FB,
As recent designs of MotoGP & Moto2 have shown stiffer does NOT always equate to better.
Under cirtain circumstances the stiffness needs to be in one plane not all planes google pics of Rossi's MotoGP frames aver the last 7 years and you will see the swing arm in particular has plates welded internally on the horizontal yet the axle positioning mechanism is deliberately thinner

For the book worm and those who have a library membership take a read of Neil Spaldings book MotoGP Technology vol 2.


On another note it seems highly unlikely that I will be returning any time soon to the UK as it is under a volcanic cloud with NO flights in or out for the fore seable future. In the mean time I have returned to the west indies

[Freestyle72]

Good to have you on this side of the pond George!

Anyways I just want this bike to be super light not only because of the handling but because I want a superbike-like power to weight ratio. The lighter the better. But I think at about 350lbs the $$ spent on lightening parts will begin to exponentiate in size compared to weight lost.

These were mods I was going to do to the bike anyway and had the pleasant side effect of weight loss. If they get me close to where I want to be, then I will continue my efforts to lsoe weight off the bike until it hits 350lbs or lighter if I can figure out places to save some weight.

[trifgeorge]

In my opinion, loosing weight, does not always guarantee better performance of the bike. For example, i modified my tail section and i took off a lot of weight. The bike is not so stable on normal road as it used to be (i haven't used in track yet) with only the rider . It will need one extra person in the rear seat to make me feel safe as i lean on curves. Maybe in track it will be different. So as i said massive weight loss is not always the best option.

[China_Racer_1]

Ok My 2 Cents is this.

I got a really built up YZF600R Engine (by Spyder) in my FZR400 frame and I have had no issues with handaling other than it wants to eat corners.

I have a simple aluminum tube subframe, Carbon fiber all over the place and reduced the weight as much as a human can. I still need to get it weighd proper but its really light.

I little flex in the whole rig is not a totally baf thing. Stiff is good but as mentioned there are some areas where thin is desired.

If I find any defects or issues with the frame after thsi season I will be sure to post it but so far so good and she is one torqued out bitch (Thanks Spyder)

P.S. if you want a better handling bike thats lighter get rid of the stock wheels and get soem lightweight ones. Unsprung weight is a huge factor in handling as well.

Drop the stator if you can but keep the flywheel if its needed for the coil pick up.

Get some after market rear sets as well. Get a lightweight exhaust system and can also.

light weight clip ons

Watch the oz's and the lbs will take care of themselves.

[Freestyle72]

@ China racer

Hey do you have any idea how much WoodCraft clip-ons weigh? Got any 50mm laying around? I am debating if I want to spend the money on some. But I can weigh the stock GSXR ones and we can do a comparision.


On any bike you can save weight in:

- Forks ohlins internals etc weigh less than stock
- Rear shock and ohlins shock weighs considerably less than a stock shock
- Light weight exhaust
- Lighter subframe (or race subframe if you will)
- Light weight hardware (aluminum and titanium)
- Aftermarket wheels
- Aftermarket Rearsets
- Aftermarket Clip-Ons
- Lighter rotors

Now since this is a street bike that I will most likely keep a naked for a year or two until I can afford the fairing set-up I want but even this will save me a few pounds by being naked. I will have to keep my stator and things like that. Also things like aftermarket wheels are way more money than I wan to spend. So I am going with late model GSXR wheels. I already have a fox shock out back so I am not entirely how much that weighs/how light it is. When I strip the bike for powdercoating I plan on weighing all those items.