Author Topic: Anybody else weigh their bike??? (Read 9629 times)

tsflstb · « **on:** January 29, 2007, 07:38:02 PM »

After riding some bigger bikes, I've been curious how much my 400 actually weighs. Came across a New Year's bathroom scale display at Wal Mart the other day. I bought two of their finest $6.00 scales and hurried home to the garage...

I balanced the bike and got the weights front and rear. I did it a few times and got the same results. I may be off a few lbs. either way, but it seemed pretty accurate.

With about 1 gallon of gas in the tank...
Front: 165#
Rear: 180#
Total: 345#

With me sitting on the bike in full gear (boxers) and using my ninja like balancing skills...
Front: 240#
Rear: 290#
Total: 530#

I've been trying to cut weight on the bike as much as possible without spending much money. Pretty much removed all non-essential doo-dads. I've still got a drilled front rotor to install that may save a couple more lbs, but this is about the lightest it can get without getting creative. Anyway, not trying to boast here, as my dyno sheet would read maybe 29 horsepower on a good day.

What kind of weight distribution is good on a bike? 50/50 on a car is pretty much the target, is it the same?

medic09 · « **Reply #1 on:** January 29, 2007, 07:41:25 PM »

I think you need to find a hobby...

CrisPDuk · « **Reply #2 on:** January 29, 2007, 07:52:24 PM »

Apart from the mountain bike, I've never really weighed any of my vehicles.

The way I look at it, If I'm happy being portly (100kg ish), there's no reason why my transport shouldn't be allowed the same rights

and as I've always preferred a big torque laden engine to high revving screamer, It's never been a problem

I would hazard a guess that, in an ideal world, 50:50 is the way to go on a bike too. Although with the rider's weight being far more significant a portion of that weight, static balancewould be less critical than a car?
Most riders will move about on the bike in order to affect it's balance anyway, thus negating any work done on the static side.

The crucial factor is the location of any weight, the more you can remove from the top of your bike, to lower its CoG, the better. The other major factor, which affects cars far more than bikes, is to get as much weight as you can within the wheelbase, as near to the polar centre as you can.

trinorman · « **Reply #3 on:** January 29, 2007, 08:11:56 PM »

You might have spent $6.00 too much. A riding friend of mine who is an engineer told me you only need one scale. I forget what law or theory it is, but he said just put your front wheel on, note the weight, then your rear wheel, and add the two together. You should get an accurate weight. Try it and see if you get the same results.

CrisPDuk · « **Reply #4 on:** January 29, 2007, 08:50:20 PM »

Quite true trinorman, theweight of any object is distributed through all it's points of contact. On a motorbike this is the front wheel and the rear wheel. Any weight that isn't borne by one, must, by definition, be borne by the other

Obvioulsy this changes if either stand is brought into the equation

Sam Green Racing · « **Reply #5 on:** January 29, 2007, 08:55:21 PM »

#$%*, them Chris guys are smart,

They beat me to it

Ya just waisted $6.00

Sam.

Raul CB750K1 · « **Reply #6 on:** January 30, 2007, 04:34:33 AM »

1. You are right about the scales, you only need one. Weigh first the front end, then the second, and add up the reads.

2. The distribution should be 50/50 but not on the unladen bike, but when the rider is on it. The weight of the rider and the riding position is key for weight distribution. You need good weight on the rear wheel to help acceleration without skidding, and weight in the front wheel to help braking without skidding. Anyway, the dinamic forces produced at braking and accelerating change the weight distribution, and for that reason the rider should compensate with his body weight. This should be clear for anybody who rides a motorcycle, I'm probably just stating the obvious....

tsflstb · « **Reply #7 on:** January 30, 2007, 05:15:55 AM »

I thought about just getting one scale, but got caught up in the moment and bought two. I'll have to double check the weights with one and see what I get. Gravity is gravity, right?

Dammit, what am I going to do with that extra scale now?

How 'bout I give it to my wife for Valentine's day? Women like gifts like that right?

sparty · « **Reply #8 on:** January 30, 2007, 05:19:51 AM »

I have one of those deluxe Tanita scales - http://www.tanita.com/IronManScales.shtml#

Tonight, I am going to weigh my bike and check its body fat.

Sparty

bill440cars · « **Reply #9 on:** January 30, 2007, 06:44:25 AM »

Okay sparty, you've gotMYattention. Pictures and details on the car in your avatar.

Did ya think you could put that out there without drawing any interest?

Give it up.

I've
already checked your gallery.

Later on, Bill

sparty · « **Reply #10 on:** January 30, 2007, 07:19:31 AM »

Quote from: bill440cars on January 30, 2007, 06:44:25 AM

Okay sparty, you've gotMYattention. Pictures and details on the car in your avatar.
Did ya think you could put that out there without drawing any interest? Give it up. I've
already checked your gallery.

Later on, Bill

Not my car, but I wish that it was. It is a heavily modified 1953 Nash Rambler Convertible, that engine is making over 800 HP. I took the picture at the World of Wheels Car show at Cardinal Stadium in AZ two weeks ago when i went down for the Barrett-Jackson Auction.

BTW, the cars at the auction was awesome, but the weather sucked in the Scottsdale/Tempe area. It was in the high 30s and rainy.
My wife ran in the PF Chang's Rock n' Roll Marathon, the morning of the marathon it was below freezing! It was warmer back home in PA.

Sparty

Geeto67 · « **Reply #11 on:** January 30, 2007, 07:29:48 AM »

I think it is better that you bought two - now that you are playing with the weight on your bike you can see how moving stuff around can affect the weight and weight bias without having to setup the scale over each wheel everytime you make a change. That is how race teams do it, and thoes guys telling you you waisted $6 are full of it.

on a motorcycle the weight bias should be a little tail heavy. M/C companies do this to help increase traction on the drive wheel. I don't know the ideal figure since it changes for every bike ( but if I had to guess between 55% and 52% rear and 45-48% front).

If you feel that you have reached your limit in what you can remove from static weight, try removing reciprocating weight. Anything turning weighs approx 10 times more than anything standing still due to the forces involved. The biggest savings I can see would aluminum rims and stainless spokes, then drill the brake rotor, and switch to aluminum sprockets. YOu may only save 10 lbs, but when you are moving the bike will respond like you saved 50 (ok I am making up the numbers but you get the point).

Looking at your bike I can see tons of things to help save weight from a couple of lbs to a couple of grams. Have you removed the electric starter?, that is a nice hefty weight you can get rid if if you don't use it. Those shocks look like showa units off a cb900f, if they are they are way heavier than works or ohlins shocks. You can swap your tank out for fiberglass. You can switch to an aluminum swingarm and run a disc brake rear (really saves you on reciprocating weight). Swap your headlights for car fog light units, just as bright but half the size and weight of a conventional sealed beam bulb and run an LED taillight.

To give you the extremes of weight loss here is a pic of a kawi triple that is road legal and about as light as you can get. I think the weight is pretty close to 300 even and the frame is heavier than the cb frame (it is a kh500 frame with an h2 750 motor). Even on this bike there is a little room for improvement, but he took nearly 100 lbs off the bike:

doug_id · « **Reply #12 on:** January 30, 2007, 07:43:29 AM »

I like that Kawa

You could still lose the front fender and steering damper though.

tsflstb · « **Reply #13 on:** January 30, 2007, 08:56:56 AM »

Good ideas Geeto...I think I've gotten most of the low-hanging fruit of weight reduction. That Kawasaki is a serious machine. I'm pleased with taking over 50 pounds from stock without spending much money. Gotta say the one biggest savings was the exhaust. Not nearly as pretty as the 400's stock header, but saved probably 20 lbs. right there.

Phase 2 is planned...remove the battery/air box, run pod filters and a small gel battery with just the kicker. I know alloy rims would make a huge difference, it's just hard to lay out the cash. I'll have to really open up the checkbook to get the next 50 pounds off. I've seen some amazing things made from Titanium at www.arcfabrication.com.

I've probably got more weight on the front than stock since those shocks are about 2" longer. I may slide the forks up a little to see what that does to the weight bias. A few pounds here and there probably don't seem like much, but its fun for me and cheaper than chasing horsepower on a bike like this.

bwaller · « **Reply #14 on:** January 30, 2007, 09:59:47 AM »

It would be very unwise to lose the damper off that thing!!

IndianRider · « **Reply #15 on:** January 30, 2007, 01:50:46 PM »

how about a 3-1 exhaust on that kawa to loose more weight ..

6adan · « **Reply #16 on:** January 30, 2007, 04:01:38 PM »

The kawi triple is a two stroke a 3 into 1 will not work. Dannie

tonys10 · « **Reply #17 on:** January 30, 2007, 04:46:30 PM »

Quote from: Geeto67 on January 30, 2007, 07:29:48 AM

I think it is better that you bought two - now that you are playing with the weight on your bike you can see how moving stuff around can affect the weight and weight bias without having to setup the scale over each wheel everytime you make a change. That is how race teams do it, and thoes guys telling you you waisted $6 are full of it.

on a motorcycle the weight bias should be a little tail heavy. M/C companies do this to help increase traction on the drive wheel. I don't know the ideal figure since it changes for every bike ( but if I had to guess between 55% and 52% rear and 45-48% front).

If you feel that you have reached your limit in what you can remove from static weight, try removing reciprocating weight. Anything turning weighs approx 10 times more than anything standing still due to the forces involved. The biggest savings I can see would aluminum rims and stainless spokes, then drill the brake rotor, and switch to aluminum sprockets. YOu may only save 10 lbs, but when you are moving the bike will respond like you saved 50 (ok I am making up the numbers but you get the point).

Looking at your bike I can see tons of things to help save weight from a couple of lbs to a couple of grams. Have you removed the electric starter?, that is a nice hefty weight you can get rid if if you don't use it. Those shocks look like showa units off a cb900f, if they are they are way heavier than works or ohlins shocks. You can swap your tank out for fiberglass. You can switch to an aluminum swingarm and run a disc brake rear (really saves you on reciprocating weight). Swap your headlights for car fog light units, just as bright but half the size and weight of a conventional sealed beam bulb and run an LED taillight.

To give you the extremes of weight loss here is a pic of a kawi triple that is road legal and about as light as you can get. I think the weight is pretty close to 300 even and the frame is heavier than the cb frame (it is a kh500 frame with an h2 750 motor). Even on this bike there is a little room for improvement, but he took nearly 100 lbs off the bike:

Actually, not true....modern motorcycles have their weight biased towards the front. They get plenty of weight transfer on acceleration and the rider weight moves it back a little anyway. Older motorcycles have a rear-bias due to short swingarms, shallow fork rake, and the mass of the motor did not allow much flexibility in placement of the motor or auxiliary equipment.

Geeto67 · « **Reply #18 on:** January 30, 2007, 07:18:17 PM »

I'm not entirely sure it is not true - new motorcycles try to have as neutral a weight bias because too much and it is a wheelie machine (like new sport bikes aren't already) but not enough and it is a smoke machine. I have been told that modern bikes us the rider more effectlvly in determining the weight bias where as older bikes were designed with the bias as the bike sits.

BTW, does anybody have a sub 400lbs cb750? I am planning a cafe racer project and my goal is to get to 380lbs wet. I have seen some drag bikes that claim to be there, just wondering if anybody else has gotten there...

Sam Green Racing · « **Reply #19 on:** January 30, 2007, 08:41:34 PM »

Is 396 any good to you

Geeto67 · « **Reply #20 on:** January 30, 2007, 10:01:45 PM »

Quote from: samcr750 on January 30, 2007, 08:41:34 PM

Is 396 any good to you

absolutley, love to know how you got there. Considering these bikes are the heavy side of 400 lbs and have been nicknamed 500-pounders 396lbs is a huge deal

it is also one of my favorite numbers because of the 67 chevelle ss I used to own.

Sam Green Racing · « **Reply #21 on:** January 30, 2007, 10:13:17 PM »

Removed every thing that was'nt needed and swapped steel for aluminum or glass where possible.

Had it been built as a drag bike instead of a race bike, I am sure it would have been much lighter.

See pics in my signature.

I know it weighs 396lbs, I weighed it on 1 scale

Sam.

Geeto67 · « **Reply #22 on:** January 31, 2007, 05:29:14 AM »

I don't see to much more you can take off that bike to make it lighter so maybe I can revise my goals. How much does that fairing weigh? I am thinking about a street bike more than a race bike so I would not need the fairing (and associated hardware) but it would be cool to have.

IndianRider · « **Reply #23 on:** January 31, 2007, 05:46:00 AM »

Quote from: 6adan on January 30, 2007, 04:01:38 PM

The kawi triple is a two stroke a 3 into 1 will not work. Dannie

didnt know that 2 strokes had to have an exhaust for each cylinder .. any reference to good articles or sources on 2 stroke tuning .. am looking to get an RD350 project next season ..

TomC · « **Reply #24 on:** January 31, 2007, 06:47:01 AM »

Hi Dannie
I have seen it done! It does work!
A single expansion chamber for each cylinder is better.
TomC

Quote from: 6adan on January 30, 2007, 04:01:38 PM

The kawi triple is a two stroke a 3 into 1 will not work. Dannie

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Author Topic: Anybody else weigh their bike??? (Read 9629 times)

tonys10