BIG speedo problem

[fixxervi6]

Problem - I'm going much faster, yes faster than what the speedo says

Background - me and the wife went out for a ride, her on a ninja 250r and me on my kat 750, she complained at times she was doing 90 to stay with me, I swore I was not speeding and she was complaining about my crazy driving.

I told her her speedo must be way off that they will typically read faster than what your going but I was doing the speed limit the entire way.

On the way back we took all highway, I was running in the 70's and she kept backing off, I asked her what was up she said she was pushing 90's and wasn't going to go that fast, I figured maybe I was reading a little slow and her's was reading a little fast to explain the massive gap.

So today I got the GPS out and just to be sure I also used a pace vehicle with GPS, the GPS and pace vehicle were 1 for 1 all the way through the speed range. Test results for my bike

my bike

my speedo gps and pace
30 ------------- 34
40 ------------- 45
65 ------------- 74
70 ------------- 81

her bike

45 ------------- 42

So I was correct, her's is reading a little fast to her real speed, and mine IS WAY OFF

This means I've been driving like a crazy man as I typically go 5 over.... according to my speedometer.

first off HOW the hell could it be that bad and second how do I fix this!!!

[1990gsx 600]

well for one quit wearing speedos JK

i would check the sprockets they may be the wrong size.

[abailey362]

normally bikes read faster than they are going so she is on par. the sensor could be off, or the sprokets could not be stock as mentioned above. How long have you had the bike and do you know what all the PO did to it?

[fixxervi6]

I've had it for a couple of months, I am second owner, original claims it is 100% stock.

Sprokets as in chain sprokets? how does that affect the speed, well I guess I see how if the speedometer runs off the transmission, but that would mean they either made the front bigger or the back smaller.. not sure why anyone would do that.

[Kreylyn]

I've had it for a couple of months, I am second owner, original claims it is 100% stock.

Sprokets as in chain sprokets? how does that affect the speed, well I guess I see how if the speedometer runs off the transmission, but that would mean they either made the front bigger or the back smaller.. not sure why anyone would do that.

You didn't post what year 750 you have, but I'm going to guess it's a 98+.

The "post" Kats (98-06) use an electronic sensor on the front sprocket to provide data on how fast your going. If this has been altered (different size sprocket front or rear) or a significant differnce in wheel/tire size on the rear can directly affect the speed displayed as compared to how fast your really going.

There is an after market electronic device you can get called a "speedo healer" that will allow you to adjust and make the speed show correctly, no matter what sprocket setup you run (for the post kat).

Krey

[fixxervi6]

you didn't post what year 750 you have, but i'm going to guess it's a 98+.

The "post" kats (98-06) use an electronic sensor on the front sprocket to provide data on how fast your going. If this has been altered (different size sprocket front or rear) or a significant differnce in wheel/tire size on the rear can directly affect the speed displayed as compared to how fast your really going.

There is an after market electronic device you can get called a "speedo healer" that will allow you to adjust and make the speed show correctly, no matter what sprocket setup you run (for the post kat).

Krey

2003

[SweetLou]

People will change sprocket size to effect aspects of the bike like gas mileage or off the line power. Increasing the rear sprocket in size will give you more get up and go off the line, but take away a bit of your top end. Reducing the sprocket will take away a bit of your get up and go off the line, but help with better gas mileage.

[Bart]

I know this sounds really weird, but I've seen this idea in another thread and it should actually work really great. Get an electronic speedometer for a bicycle.

They're battery-powered, so you don't have to worry about wiring issues. It's usually a button-cell, maybe a single AAA size worse case scenario. Just affix one tiny magnet to your wheel, and one to the fork. Then all you have to do is program in in the diameter of your wheel. Supposedly they're accurate up to something like 180 mph (will probably vary by brand).

I used to be a die-hard bicyclist, had several bikes and several computers, loved the things. "Back then" the prices ran usually $12-30. Now it's probably $15-60.

There's a few drawbacks. It should be accurate, but may take a second to process when you're changing speeds. That and the screen will go blank after a few seconds if you stop (to conserve battery life). On the flip side the more expensive ones read out all kinds of goodies like trip distance and average speed.

C'mon, digital readout, kit comes complete with a handlebar mount and everything (or just velcro it someplace convenient). You know it's tempting.

[fixxervi6]

seams like a good idea, but speedo healer sounds like the "right" way and would help my resale value

[Mozzy]

well, leaving it could also help with the sale...

"Man, I pushed that kat and it felt like i was flying while only doing 70, it feels way faster than my other bikes"

[RidgeRyder84]

Speedometer not working on my 2000 Kat 750

Do any of you guys know what this could be from as I just put a 95 750 motor in my 2000 frame because I had a rod knock in the old one but now everything works fine except my speedometer is not working! I had a JT 14 tooth sprocket on my old motor that I swapped on onto my new motor and I checked all my wiring and everything seems fine. Its extremely annoying with not being able to figure this issue out...

[scottynoface]

1.) Way to bump a two year old thread with an irrelevant post.

2.) Pre 98 speedo drive was on the front wheel, post 98 was off the front sprocket...so unless you have a pre 98 wheel or added a speedo pickup to your post 98 wheel...well thats why your speedo doesnt work, because it's not hooked up.

[RidgeRyder84]

Its the post 98 wheel. Only conclusion Im coming to is that the speed sensor is bad. It worked last fall when I put it away for the winter but now that I got it back out and put the new motor in it, it doesn't work. everything on the gauge cluster works except for the speedodometer and the mileage. I just didn't want to spend $107 for a non returnable part being the speed sensor

[95GSX600noob]

Its the post 98 wheel. Only conclusion Im coming to is that the speed sensor is bad. It worked last fall when I put it away for the winter but now that I got it back out and put the new motor in it, it doesn't work. everything on the gauge cluster works except for the speedodometer and the mileage. I just didn't want to spend $107 for a non returnable part being the speed sensor

One thing you need to know is the pre engine don't have the same wires coming off the trans side of the case. There should be one blue wire that is on the pre and the post engine have the same blue wire with another loom next to it that has a 2 plug connetor.. Unless there is a way to get the pre engine to read speed off the out put sprocket but im not to sure on that. To me it sound like you don't have a wire hooked up and she is not goona work..

By the way you should have posted a new thread....

[05RedKat600]

Yeah, there's your issue. You probably used the Pre sprocket cover....and that's not gonna work with your speedo. You need the Post sprocket cover, but then you'll need to play with the pushrod as the Pre's and Posts are different if I remember right.