SuzukiSavage.com - Print Page

SuzukiSavage.com
/cgi-bin/YaBB.pl
General Category >> Rubber Side Down! >> You learn something new every day....
/cgi-bin/YaBB.pl?num=1211834558

Message started by skrapiron on 05/26/08 at 13:42:38

Title: You learn something new every day....
Post by skrapiron on 05/26/08 at 13:42:38

A few months ago, there were several posts from owners and former owners lamenting that their Savage just could not go any faster than 80mph. I found out why... The hard way.

On my way to Sandusky on Friday, I was reminded by a very nice Ohio State Trooper that the speed limit on the Ohio tunrpike is 65mph. He was nice enough to give me a $108.00 reminder. Somehow, he clocked me doing 78mph in a 65. Thats impossible, since I had my throttle lock set at 70mph.

Once I met up with Mrs. Skrapiron, I had her pace me in the CR-V. Sure enough, my 60mph (indicated) was registering 66mph in the CR-V.

Since there was such a discrepency, I used her odometer to calculate my fuel economy. According to her odometer, I traveled 141.5 miles from my parents to home. According to the bikes odometer, I only went 127.7 miles.

Why the big discrepency? I change my final drive ratio.

I put on a 140/90-15 rear tire. The stock tire was 140/80-15. That difference in circumference is enough to make the speedometer even more inaccurate.

The speed is measured by engine revolutions, not tire revolutions. By changing the drive ratio, it affected the speedometer. (When I am showing 50mph (indicated) I am actually travelling 55mph).

That being the case, if someone does the chain drive conversion, they will expereince the same discrepency. If they do the chain conversion WITH a larger rear tire (140/90-15) that sill be as much as 15-20% speedometer inaccuracy.

So if your bike is topping out at 80mph (indicated), you are likely in excess of 85, perhaps 90mph.

Next time, before you blame the bike, check the accuracy of the speedometer. Or, you can do like me, and use the freindly neighborhood State Trooper to verify the accuracy.... :P

Title: Re: You learn something new every day....
Post by justin_o_guy2 on 05/26/08 at 13:46:28

So, the 94 I saw on the way home from church was WHAT? I have a 140/90-15 on the rear, too.

Title: Re: You learn something new every day....
Post by skatnbnc on 05/26/08 at 13:51:29

554A4C4B5651605060584A460D3F0 wrote:

So, the 94 I saw on the way home from church was WHAT? I have a 140/90-15 on the rear, too.

The sermon must have been really boring for you to want to leave that fast! ;D

Title: Re: You learn something new every day....
Post by justin_o_guy2 on 05/26/08 at 13:53:29

I WAS deeply disturbed. My Pastor, a man I have had great respect for, disclosed that he listens to Oreilly every night, on Fox. WHO listens to that hate? I was shocked & lost a LOT of respect for the pastor.

Title: Re: You learn something new every day....
Post by bsdnfraje on 05/26/08 at 14:59:56

Did Obama ever do 90+ going home?

If I sped home every time I heard a homily that made me sick to my stomach, I'd have a wall of tickets.

As a catholic, you get used to garbage sermons. The upside is, when someone really gets up there and preaches the faith, you're on cloud nine for a few days.

Btw, I've found if I break the TON much, I only get 80 miles to the tank, insead of 100. I ain't rich enough to push the throttle these days.

Title: Re: You learn something new every day....
Post by LANCER on 05/27/08 at 03:45:29

This issue is one of the reasons that I like using the Veypor on my bikes. Regardless of what changes are made to the gear ratio with sprokets or tire size, just measure the circumference of the rear tire and plug that info into the computer, run through the gears on time, and it will calculate the exact speed and distance you are actually traveling. It also keep track of you fuel status, miles traveled, miles to go before empty....etc etc etc.
It is a handy tool.

Title: Re: You learn something new every day....
Post by furious70 on 05/27/08 at 06:57:15

actually the speedo on my wife's reads about 7% faster than she's actually going, so a bigger tire would probably make it pretty close to right on, depending on the % diameter increase.

Title: Re: You learn something new every day....
Post by verslagen1 on 05/27/08 at 07:41:25

So far my Veypor says the speedo is dead on. And that is with the 140/90-15.

Do you want to know how speedo's work their magic? That speedo cable spins round and round and drives a disk with several magnets attached to it. These magnets are in close proximety of another steel plate that magnets tug at and try to make spin too. But there's a spring attached to this plate to keep it from spinning. The faster you go, the more this plate twists. Attached to it is the needle that you are so found of watching.

I worked for a flow meter company and they took auto speedo's and recalibrated them for their use. This was done with a magnitizer that adjusted the strength of the magnets in the speedo.

Title: Re: You learn something new every day....
Post by KwakNut on 05/27/08 at 08:12:12

6C7F7863657F793D3A0A0 wrote:

actually the speedo on my wife's reads about 7% faster than she's actually going, so a bigger tire would probably make it pretty close to right on, depending on the % diameter increase.

7-10% over-read is what you can expect on the majority of factory standard bikes and cars on the road.
The manufacturers have to be sure that the gauge doesn't under-read for legal reasons, and they don't mind going on the safe side because it makes people think their vehicle is faster than it actually is.