Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Dan_Lockwood]

I know there is a separate section now that Steve responds directly in, and he was a BIG help in getting me back up and communicating with my ECM, but I was thinking that MORE people would see this question here than in the support forum.

I'm thinking some of the more experienced guys may have "played" with the VSS number to tweak it a bit.

My background is this, I just did the 30t front sprocket and used the TTS VSS calculator and picked my bike and year as well as the tire roll out for my exact tire size.  When I did this I got a number.  I entered this number into the VSS save and I'm off just a mph our two.

I'm being very nit picky about this I know.

I was told the higher the number the slower the speedo reads; and that's how mine worked out.  My "number" got larger and my speedo read slower.

My question is this, how many numbers for 1 mph change slower or faster reading speedo? As an example, I go from VSS 2159 to 2179, an increase of 20 numbers, and I see a lowing of 1 mph.

If you use TTS, I think we all have about the same "type" of bike, touring that is.  So if someone has "played" with the numbers to get that one or two mph change in the speedo, can you help a guy out?

Also, how linear have your VSS settings been?  As an example, at 40 mph you're 1 mph slow and at 70 you're still 1 mph slow.  Or have they been non linear and you're on at 40 and at 70 you're 4 mph slow?

I'm sure I can hook up my PC and make a minor change and go try it, but I would prefer to do this just one more time and be done without having to do it several times to get it dead nuts.

Thanks in advance.

[grc]

The linearity of the reading isn't something you can affect with the VSS adjustment.  That's more of a manufacturing tolerance thing in the speedometer itself. 

Just my humble opinion, and I do understand the OCD-like desire to have it exact since I tend to suffer from the same thing, but unfortunately no matter how close you get the VSS setting to give you say exactly 60 mph indicated at 60 mph actual, it will change over time as the tire wears, then back again when you install a new tire, et cetera.  This variation due to tire wear can be from 1 to 2 mph all by itself. 

Jerry

 

[Dan_Lockwood]

Understood Jerry.  I appreciate you vast experience and knowledge.

Yes, I'm being very picky about this and maybe I should just go with the flow, so to speak.

How linear the speedo correction is, is as you say probably a tolerance programming thing.  I know that in our machines we count infeed screws rpms, one rpm is one plastic bottle entering the trimmer.  We control the speeds with VFD's and just increase / decrease Hz to change the speed of the trimmer.  Our programmer has a button the HMI to adjust bottle speed, but it's only accurate between about 100 and 150 bottles per minute.  It gets slow the lower you go and reads fast the faster over 150 bpm you go.  The control multiplier ratio number off I'm sure.  But our guys are not going to spend hours trying to get it better, they tell me to just live with it and let the customer know approximately how far off it is and the extreme bpm ranges.  Sorry for rambling.

I'm just looking for feed back and to be honest, I've not yet done a 40, 50, 60, 70, 80 GPS comparison to see just how linear my speedo is.  But I do expect that it's probably NOT linear throughout the main range we ride in.

I'll just sit back and see where this goes.

[GWN]

The adjustment is as easy as calculating what % you are out and adjusting the VSS number by the same %. In my case it was 4.5% and the speeds were very close throughout all the ranges, and I checked it with 2 different hand-held GPS units as the infotainment speed is the same as the speedo,i.e. not GPS generated. Now in your case a different front sprocket may not give you a linear correlation, in which case you dial it in for the speed you feel is most important. The change in actual speed of a new tire vs a worn tire is usually less than 2% (7mm of wear on a tire 640 mm tall) so you can adjust for this as well if you think it is important.

[Para Bellum]

Also, how linear have your VSS settings been?  As an example, at 40 mph you're 1 mph slow and at 70 you're still 1 mph slow.  Or have they been non linear and you're on at 40 and at 70 you're 4 mph slow?

I believe you will find that the error is a percentage, no matter what speed you're running.  So if it reads 52 mph at an actual 50 mph (4%), then it will read 104 at actual 100.  That would be considered linear.

[Dan_Lockwood]

Thanks everyone...

I'll do another speed check this weekend and do the percentage and see if it's the same from low to high.  Then I'll just bump my VSS number by that percentage and hopefully just do it one time.

Thanks again.