Author Topic: Fork springs on a B4 (Read 5321 times)

Racerruss-ducati · « **on:** June 19, 2005, 11:41:35 PM »

Does anyone know the stock rate of the '93 B4 fork springs. I need to up the rate a little (the bike sags about 50 mm on the front and 45 on the rear) and I need the baseline to determine which one of the 5 rates that are offered by racetech is the correct one.

I will also be doing a GSX-R shock swap in the next couple of weeks. I am going for a '00-'03 shock. The threads on this board have a lot of good info on this swap and I hope to get the bike up off of the deck (at track days, pipe drags hard on right side) and prevent busting my ass again.

millsi1 · « **Reply #1 on:** June 20, 2005, 01:33:50 AM »

im hearin ya on the right side zorst scraping!! i also scrape the side stand. let us know how you go putting in the new shock.

gsxr400 racer · « **Reply #2 on:** June 20, 2005, 02:39:14 PM »

.90 IS WHAT YOU WANT

Racerruss-ducati · « **Reply #3 on:** June 20, 2005, 08:45:16 PM »

Thanks for the advice on the springs GSXR400 Racer. I am about 190 lbs, do you still recommend the 0.90, or should I go for the 0.95?

Thief400 · « **Reply #4 on:** June 20, 2005, 10:05:09 PM »

The stock springs are .574 Kg/mm, the springs in the 91 750 Katana front end I installed are .629 Kg/mm and they are right on for my 230 lbs'
If you go all the way up to .9 or .95 you better do something with the damping to control that heavy of a spring rate! The stock damping rod sure wont.

gsxr400 racer · « **Reply #5 on:** June 21, 2005, 12:06:23 AM »

race tech springs are way different than stock bro! hense the high numbers if your taking it to the track and gonna wear leathers and weigh that much id say .95 i have .85 in mine and weigh 160. on a good day but my gixxer 4 is under 300 lbs wet!

Racerruss-ducati · « **Reply #6 on:** June 26, 2005, 09:06:25 PM »

How do you get a B4 under 300 lbs??? Fill the tires and the tank with helium? That is more than a 70 lb savings!!

Seriously, I looked mine over pretty closely and other than ditching the center stand, side stand and signals (~10 lbs), there appears to be little to save. If you use an all carbon body, including the tank and $2500 magnesium wheels (maybe 20 lbs.), I can't see where that kind of mass could be saved. Please give us all a rundown of the light parts.

BTW, I have 0.85 kg-mm Race-Tech springs (they didn't have the 0.90 in stock) and a '03 GSX-R shock coming. I will try to document the shock change with pictures and post when finished.

b4cruz · « **Reply #7 on:** June 26, 2005, 09:25:09 PM »

Quote from: "gsxr400 racer"

gixxer 4 is under 300 lbs wet!

wow you gotta start a thread on how you lost 96 lbs off the bike

Red01 · « **Reply #8 on:** June 26, 2005, 09:41:43 PM »

Near as I can tell from SuzukiCycles.org, the '88 GSXR400 weighed 352 lbs (dry).

Not sure how much weight would be saved by dumping all the street gear, replacing the stock exhaust with an aftermarket header and replacing the street bodywork with race weight stuff, but I'm sure that's pretty substantial.

Racerruss-ducati · « **Reply #9 on:** June 26, 2005, 10:07:55 PM »

According to the Suzuki manual, the dry weight is 364 lbs for the '91-'93 US model.

I have had my stock exhaust off and it is amazingly light for a stock system. I cut off the muffler and replaced it with a carbon Muzzy slip on, but that only saved about 3 lbs. Like I said, I want to know what I am overlooking.

gsxr400 racer · « **Reply #10 on:** June 27, 2005, 12:14:57 AM »

Quote from: "Red01"

Near as I can tell from SuzukiCycles.org, the '88 GSXR400 weighed 352 lbs (dry).

Not sure how much weight would be saved by dumping all the street gear, replacing the stock exhaust with an aftermarket header and replacing the street bodywork with race weight stuff, but I'm sure that's pretty substantial.

considering the header by it self weighed 25lbs steel, my frame is aluminum, subframe 02 gsxr race subframe aluminum ( one of my dual carbon cans weighed more than my new stainless race header, no airbox, (stock subframe was aluminum long with steel grab rails and mount for the tail light) no head light , sharkskin race bodywork, penske shock , lighter wheels even tho i got a 180 rear tire ! it wasnt hard . my street b4 will also have a newer suzuki gsxr aluminum subframe grafted to it they seem to lline up well if you know how to weld tabs or know someone who can weld. i have carbon fiber clipons seat mount was steel now alum. radial master cylinder! i could go on and on! havent got into the tittanium bolts and odds either.

Red01 · « **Reply #11 on:** June 27, 2005, 01:50:12 AM »

Quote from: "Racerruss-ducati"

According to the Suzuki manual, the dry weight is 364 lbs for the '91-'93 US model.

I didn't think the US ever officially got the GSXR400...

Quote from: "gsxr400 racer"

on a good day but my gixxer 4 is under 300 lbs wet!

(Emphasis added)

Quote from: "Racerruss-ducati"

How do you get a B4 under 300 lbs???

Remember, he didn't get a B4 under 300, he got a GSXR400 under 300.

b4cruz · « **Reply #12 on:** June 27, 2005, 02:58:07 AM »

Quote from: "Red01"

Remember, he didn't get a B4 under 300, he got a GSXR400 under 300.

still wet a gsxr would be over 360lbs right?
how do you take over 60lbs off a bike!

share the secrets please

Racerruss-ducati · « **Reply #13 on:** June 27, 2005, 08:22:41 AM »

My bad. I thought the GSX-R 400 and the B4 were basically the same bike, just relabeled for the different markets. Thanks for the correction.

jcmjrt · « **Reply #14 on:** June 27, 2005, 11:48:58 AM »

GSXR400, do you know which GSXR aluminum subframe can work on a GSF400? Any idea how much weight is saved with that? Also, I'd like to hear/see more about the change in wheels. 17inch wheels are nice for getting modern rubber but I wonder what's involved in the change and what kind of weight savings there is? Thanks for sharing all your racer tricks!