First thousand miles: questions...

[Deleted member 4372]

Greetings--

I'm loving my NC DCT, and after my first couple weeks and 1k+ miles have a few questions:

My speedometer, compared to GPS, reads 5-8 MPH fast, depending on speed. Perhaps the previous owner installed larger (smaller?) than stock tires? I've read here that the speedo is quite accurate, so I'm perplexed.

I find the throttle "notchy", i.e. Not smooth at zero to 5 MPH. The throttle also sticks a bit, like a throttle lock without a throttle lock installed. Has anyone tried the G2ergo.com throttle cam?
Where do I start solving the sticky throttle? Tube? (I'll be taking the grips off soon to install heated grips) or cables? (Might just need lubing?)

I'm slowly getting the bike kitted and fitted. Buell footpegs ordered. Givi E41s installed. Rox Risers in transit. Canada trip in planning. NC? Why did I get that Wee Strom (soon to be for sale)?

Thanks, all

Rainier

 

[showkey]

Stock setup the speedo is very accurate. What size tires on the bike now ????

 

[Grey1one]

From reading one of the other threads on this forum, changing the sprocket size can also throw it off.

 

[Deleted member 4372]

Front tire is 120/70 x 17 = stock. Rear is larger than stock, it's a 170/60 x 17 (stock is 160)
Speedo is reading, I assume, the front wheel. Not sure if there's more data going into speed determination. Why would sprocket size matter, except if speedo is getting data from there, too? I'm confuzzled.
I have service records for the bike since new. The previous owner provided them and while the chain and sprockets have been replaced, the sizes indicated were according to spec, i.e. original tooth-count front and rear.

 

[b_rubenstein]

The speedometer is not mechanical and speed is taken from the drive system.

 

[670cc]

Speedo reads from transmission, so the sprocket gearing or the rear tire size will affect it's accuracy.

US models are generally accurate to 1-2%.

 

[rippin209]

Speedo reads from transmission, so the sprocket gearing or the rear tire size will affect it's accuracy.

US models are generally accurate to 1-2%.

I hadn't thought about that I wonder how big of a difference my going from a 43 down to a 41 tooth rear sprocket has made?

 

[mreric]

if the grip sticks a bit might need to lubricate your cables. check the slack.

 

[670cc]

I hadn't thought about that I wonder how big of a difference my going from a 43 down to a 41 tooth rear sprocket has made?

2/43=0.0465 or 4.65%.

 

[MZ5]

Rear is larger than stock, it's a 170/60 x 17 (stock is 160)

That's most of the speedometer problem.

The throttle might be an adjustment/slack problem. I don't recall whether the owner's manual describes the adjustment procedure, or if that's only in the service manual. I have a copy of each at home. Check slack, and have your dealer adjust it if it's out of spec, since it's a new bike.

Excessive chain slack can exacerbate jerky feeling throttle action, too. I'm guessing your chain is _not_ too lose, but it doesn't hurt to check. Most of us run our chains at the loose end of spec, but most of the shops I've been to set them up tighter. That's nicer for drivetrain lash reduction, but I don't like it for noise and wear reasons.

 

[Deleted member 4372]

well, the sticking throttle was a stricking grip. When I pulled the grips off to put on the heating element, I noticed the throttle grip was clipped over the raised part of the plastic on the inner end of the throttle, and then jammed against the switch housing: effectively a throttle lock. Could account for the notchy throttle effect, too.
I pulled off the grip and the throttle performed as it should, snapping back as designed.
Sort of a Caterpillar tractor O-ring throttle lock without intention and without the O-ring. I'll have to ride it before I can tell if that is the throttle smoothness problem, too.
The rear tire is larger than stock but also quite new. I'll want to wear it out before replacing it. Guess I'll keep the GPS in place while I ride!

 

[showkey]

^^^^^^^^^^^^^^^^^^^
I am running a 170/60-17 705 on the rear and it changed the speedo to read 1 MPH fast at 60.

 

[Deleted member 4372]

1 MPH seems what I thought would be the effect. I'm showing 6 to 8, depending on speed, that is at 70 on the GPS the speedo shows 78; at 51 on the speedo, the GPS shows 45.
It's not at all clear to me how the bike determines speed. Just thumbing through my new manual and saw a reference to the front wheel's speed sensor. I'm diffused and confuzzled still.

 

[L.B.S.]

1 MPH seems what I thought would be the effect. I'm showing 6 to 8, depending on speed, that is at 70 on the GPS the speedo shows 78; at 51 on the speedo, the GPS shows 45.
It's not at all clear to me how the bike determines speed. Just thumbing through my new manual and saw a reference to the front wheel's speed sensor. I'm diffused and confuzzled still.

The sensor on the front wheel (and the same one on the rear wheel) are for ABS, not speedometer duties

 

[670cc]

1 MPH seems what I thought would be the effect. I'm showing 6 to 8, depending on speed, that is at 70 on the GPS the speedo shows 78; at 51 on the speedo, the GPS shows 45.
It's not at all clear to me how the bike determines speed. Just thumbing through my new manual and saw a reference to the front wheel's speed sensor. I'm diffused and confuzzled still.

For the speedometer, the manual transmission bike uses a sensor triggered by the teeth on one the transmission input shaft gears to get a signal relative to rear wheel speed. It is a gear set where the driven gear is fixed to the output shaft, so even though it senses the input shaft gear, it is proportional to rear wheel speed no matter what gear the bike is in. The DCT may use that same sensor, although since it has more sensors than the manual, it could be that same one or it might use one of the others (I don't have the book accessible at the moment). The speedometer is not referenced off the front wheel abs ring.

 

[Grey1one]

My speedo reads about 1 mph high according to my Zumo & the GPS app on my phone, I can live with that.

 

[TigerDude]

I hadn't thought about that I wonder how big of a difference my going from a 43 down to a 41 tooth rear sprocket has made?

about 5% low

 

[TigerDude]

the throttle shouldn't stick at all and should fail your t-clocs inspection right now.

theoretically a 170 vs 160 tire should be less than a 1% difference.

 

[Deleted member 4372]

Never had ABS before. Never occurred to me that the front wheel sensor would be for anything other than speedometer. Thanks for the heads up. This old dog is still able to learn. Thanks, all of you!

 

[Deleted member 4372]

I solved the sticky throttle by moving the brake MC/mirror and the switch casing in about 1/8 inch. Hoping that will also smooth out the throttke. Did learn that there is a cam throttle change available through the site I cited above.