BUILDING AN I.C.B.M. KATANA 1100

[Anonymous]

Do either of you dudes have the stock numbers for a gs or a kat? Just to get a base ine.

Sorry Kman, I don't have any numbers for a Katana. I wish I would have taken some measurements on my stock GS1100E before I did the mods. There are lots of them in here though so it would be interesting if someone would make some measurements for us.

My first measurements were with the bike on it's suspension. I got closer to 10 degrees with it lifted properly. I was going by eyeball before and didn't do too bad.

I have the 954 triples purchased now. I can't wait until i get some more parts to sort this out some more. I know the rear spring rate is going to be a bear to sort out. It's off a 750 and it feels pretty stiff right now.

I've several dirt bikes and I know all about static sag and sag with the rider. It's very important. If that isn't right you can't possibly make adjustments work correctly. I need to look up the spring rate for a 750 to get a baseline.

I love this kind of stuff. You guys are teaching me a lot. I really appreciate it.

[Anonymous]

stock numbers for a base line

No Katman, I don't know what the stock numbers are on these bikes because they are so far from anything that works that I never paid any attention to them, even twenty years ago. Back then things like swing arm droop were only understood by a very small number of folks and they were not likely to share what they new. The Japanese had figured out how to make power but they were just scratching the surface on how to get them to handle.They tended to copy the British, who knew how to make low powered bikes handle but had no clue about how to make power, so many of their ideas did not transfer to the more powerful Japanese machines. Today there are ten thousand peaple in the US alone that understand more about chassis dynamics than even the most savy race tuners from the 80's. The british used to believe that a good handling bike should have the countershaft, swing arm pivot, and rear axel on the same plane. In other words, little or no swing arm droop, especially once sag was factored in. This works with 50 horsepower, it doesnt with a 100.

[Anonymous]

proper spring rate

Hi Sammy. The proper spring rate may not be that bad to figure out, my guess is that the spring is way soft, but I have been wrong before. What year gsxr did you use on the back of your bike? How much do you weigh? Have you checked the sag yet? When you do what happens to your free sag or what I call static sag when your total sag is set at 35mm(aproaching the upper limit for the rear)? Some shocks can get away with less free sag than others(Penski) but none like less than 5mm in the rear, most require at least 10mm. With a spring that is too soft you usually can not get the total sag right without going below the bare minimun on the free sag.

[Anonymous]

Re: proper spring rate

Hi Sammy. The proper spring rate may not be that bad to figure out, my guess is that the spring is way soft, but I have been wrong before. What year gsxr did you use on the back of your bike? How much do you weigh? Have you checked the sag yet? When you do what happens to your free sag or what I call static sag when your total sag is set at 35mm(aproaching the upper limit for the rear)? Some shocks can get away with less free sag than others(Penski) but none like less than 5mm in the rear, most require at least 10mm. With a spring that is too soft you usually can not get the total sag right without going below the bare minimun on the free sag.

I'm using a 2002 GSXR750 swingarm. I haven't checked the sag yet since the bike isn't complete. I need a battery, tank, seat, etc. I tip the scales at around 220 in the summer.

I won't have a problem checking the sag. However, if I don't know what spring rate I have, how do I order another if it's not right? I'm doing some internet searches with no luck just yet.

[Anonymous]

I won't have a problem checking the sag. However, if I don't know what spring rate I have, how do I order another if it's not right? I'm doing some internet searches with no luck just yet.

Swanny, if you can measure some basic dimensions for the current spring, I can calculate the rate for you. Springs are one of the few things in this world that can be designed on paper and actually have the final result be the same as the calculated one.


Mark

[Anonymous]

spring rate for 2002 gsxr 750

Hi Sammy. i am not sure what came on the 2002 gsxr 750 but the most common spring for guys roadracing them is 425 so i imagine stock is pretty close to that. Spring rates vary dramatically on these things due to the different linkage ratio's that are used. For example the 99-2002 sv650's often use a 650 lb spring, while the 2003 version of the same bike uses a spring that is 150lbs lighter and as I mentioned the 2002 gsxr 750 uses one that is 225lbs lighter. Did you keep the stock geometry in the rear suspension linkage? One last thing. do you have a front suspension on your bike yet? the reason i ask is that I heard you mention that you just bought 954 yokes. You can not check swing arm droop untill you have a front suspension on the bike and it is set at an approximate height. this is becasue lowering the front reduces swing arm drop and raising the front does the opposite. Even going to a taller profile rear tire reduces swing arm angle. The 12.5 is just a base line setting. It is not carvbed in stone, but I wouldn't spend a lot of efort acheiving it, untill you have an approximate front ride height figured out. Steve

[Anonymous]

Re: spring rate for 2002 gsxr 750

Hi Sammy. i am not sure what came on the 2002 gsxr 750 but the most common spring for guys roadracing them is 425 so i imagine stock is pretty close to that. Spring rates vary dramatically on these things due to the different linkage ratio's that are used. For example the 99-2002 sv650's often use a 650 lb spring, while the 2003 version of the same bike uses a spring that is 150lbs lighter and as I mentioned the 2002 gsxr 750 uses one that is 225lbs lighter. Did you keep the stock geometry in the rear suspension linkage? One last thing. do you have a front suspension on your bike yet? the reason i ask is that I heard you mention that you just bought 954 yokes. You can not check swing arm droop untill you have a front suspension on the bike and it is set at an approximate height. this is becasue lowering the front reduces swing arm drop and raising the front does the opposite. Even going to a taller profile rear tire reduces swing arm angle. The 12.5 is just a base line setting. It is not carvbed in stone, but I wouldn't spend a lot of efort acheiving it, untill you have an approximate front ride height figured out. Steve

Steve, Here's a link to the last few pages of my project. I don't want to hijack Katman's thread. Yes, the front suspension is on, but as you say, the geometry will change with the 954 troples. I tried to keep the geometry the same on the swingarm also. That was trickey - the frame was modified quite a bit for that.

http://www.thegsresources.com/_forum/viewtopic.php?t=4486&start=60

[Guest]

No worries you guys this is great info. MIght be an idea to start a suspention tuning tread for ease of searching later though. I don't mind at all it being discussed here either.

Could one of you guys post the formula for the droop? eg: D=P(pivot)-A(axle)/S(pivot to axle length) and so on?

That way us gear heads could just plug in our numbers and get the answers we need......

[Anonymous]

thread hijacking

Hi Katman. I am new to computers, this one belongs to my stepson, but anyway I am not up on forum etiquit so if I did anything improper I wil apologize in advance. I am going to look at Sammy's project but I will be back. If either of you guys want to start a suspension tuning thread, i'll be happy to contribute. Steve

[Anonymous]

No worries you guys this is great info. MIght be an idea to start a suspention tuning tread for ease of searching later though. I don't mind at all it being discussed here either.

Could one of you guys post the formula for the droop? eg: D=P(pivot)-A(axle)/S(pivot to axle length) and so on?

That way us gear heads could just plug in our numbers and get the answers we need......

Ok,

cosine = Drop(pivot - axle)/Length(pivot to axle)

Once you have the cosine use a calculator or table to find the associated angle.

[Guest]

oh my....

I sorted out the issues today.....

put on a rejetted set of 33 smoothies for a comparison to see if it was carbs or ignition.....welll this thing lit up like a rocket. stood straight up in 1st and 2nd and ripped to redline. My baby has woken up.

my flatslides were way to jetted. took off the 135's and put on 125's and it was 60% better. going for 120mains tomorrow and I think that will do it.

the 33's has 125 mains and I couldn't keep the front end down or the tire from spinning.

My bandit arm is ready tomorrow so will post pics of it in a couple of days when I install it.

[Hoomgar]

Just leave the smoothies on it man

Sounds like it is rockin!

[Guest]

Good to hear that you got your problems sorted.

Just waiting to hear about the bandit arm.

[Anonymous]

smoothbores

Sounds like the smoothbores are working great! Im not sure that the flatslides make anymore power but they may hit a little harder when you first turn the grip. Flatslides are also more prone to vacume sticking. i don't think you can go wrong with either set. Sounds like the front tires are going to last a long time!

[Guest]

IS ANYBODY DIGGIN THIS?????

2002 bandit 1200 swingarm is on with a 93 gixxer armless caliper......