Topt end speed check on 2011 apex xtx

[Blue Dave]

We done all this testing years ago. The old speedos were purposely reading high. The faster you go, the more off it was. Grinding one tooth off speedo gear brought it closer to reality at slower speeds and grinding 2 teeth made it closer at top speed. The odometers were always close to reality, about 2% from my experience. Grinding teeth off gear unit threw the odometer off. Yamaha got called out on it and gradually fixed it closer to reality.

Dan

Thanks for confirming this Dan. My testing produced the same results with a non linear speedometer error (+5% at 50 MPH and +15% at 100 MPH) with the odometer being within a couple % of accurate. Because the speedometer error is non linear and the odometer is accurate I agree that this had to be a deliberate manipulation of the speedometer display programming by Yamaha.

I am sure that there is a way to fix the non linear speedometer error electronically but it would involve a factory only interface and proprietary software. Each speedometer pick up gear tooth removed reduces the signal pulses by 6.7% so yes it would require one tooth removed for "trail speed" correction and two teeth removed for "lake running" correction. However because I like my odometer accurate I am going to leave my speedometer pick up gear alone and enjoy my optimistic speed readings!

 

[sleddog66]

my findings:
125 mph on speedo = 110 mph GPS.....a factor of .88 percent
15 teeth minus 1 tooth.... a factor of .933333 percent
15 teeth minus 2 teeth.... a factor of .866666 percent

So 2 teeth is slightly too much at top speeds, and I would prefer not to go too much. As Dano stated, the lower speeds brings 1 tooth removal even closer

 

[Blue Dave]

my findings:
125 mph on speedo = 110 mph GPS.....a factor of .88 percent
15 teeth minus 1 tooth.... a factor of .933333 percent
15 teeth minus 2 teeth.... a factor of .866666 percent

So 2 teeth is slightly too much at top speeds, and I would prefer not to go too much. As Dano stated, the lower speeds brings 1 tooth removal even closer

Your decimal point is off by two places (if you want to express your values as a percent) but I get what you are saying.

Ok, so your actual GPS MPH was 0.88 or 88% of displayed MPH. I think mine was a little more off on the high end but I was having a hard time looking at both my GPS and my speedometer at 100 MPH..... or should I say 88 MPH.

Thanks guys for the feedback. I guess that I will just wait for that ground breaking game changing 2014 Yamaha sled which I am sure will have an accurate speedometer! LOL!

 

[Terminator]

hey guys, FYI went out and ran the new to me 2011 apex xtx. I had a gps run of 116 mph on a iced up road. the only modification is that the track is studded 2 per bar with 1.375" studs. No other mods whatsoever. I must say that the speedo on these newer models are a lot more precise than the older model apex's. for the Canadians I was showing 192 k/h on the speedo and 186 k/h on gps. aside from the top end being off by 6 k/h (3.7mph), the speedo seemed to be very close all the way though out the range.

Getting back to the original question, The fastest i've got w/ my 2011 XTX is 100 mph GPS, 104 on dream meter which is much closer than my older apexes, 2 studs up the middle like yours. This was across a lake on hard pack.

 

[polarisconvert]

How many miles, and what Rpms are you running.

 

[tomanytoyz]

I say if you have GPS,why screw around making the stock unit accurate? good to hear that its much closer.traction has a lot to do with accuracy on the stock speedos.(example) 20mph on GPS with an asphalt track would be what on the stock speedo??