Triumphrat

SR1 · 02-12-2006

Ok, I just finished my front sprocket mod and I guess it was worth it. She will almost wheelie now in 2nd when shifting hard from first. I know if I dump the clutch in first at takeoff she will, but she always would. It seems a little faster, or maybe I was just hoping for that. We'll see.

Windblown · 02-12-2006

Out of curiousity what did your idle MPH come down to? I'm contemplating a switch to an 18 tooth front. I really notice the tall first gear on mine in traffic. Luckily though I don't have to spend too much time in traffic. Still, a little shorter first gear would be nice.

Have you done any other mods to affect performance?

SR1 · 02-12-2006

I'll let you know tomorrow.

02-13-2006

Has this affected your speedo? I think the speedo is driven by the gearbox and reads to high when the sprocket is changed? Or has the speed per revs come down proportionately?

BEL

Stlakid · 02-13-2006

My idle speed is around 5-7mph if I remember correctly. The speedo is driven off the front wheel so no problems there.

trafficfixr · 02-13-2006

i live near NYC and this mod has made heavy traffic suck so much less than it did before. still sucks, but now it is manageable without feathering the clutch to keep from stalling or bucking. you can idle the bike and its not lurching toward the car in front of you anymore.

SR1 · 02-13-2006

My idle is around 9.5 mph now. Was around 12. Today I did a 2-3" wheelie shifting into 2nd after I was running 1st really hard. 70 mph (indicated) is 4100 rpm in 6th gear, and you could go as far as about 67mph without lugging it in 6th now.

I did a top-speed pull just for fun. I had never gone this fast so I don't know if there was an appreciable difference, but I started at 80 and turned the fast knob all the way. I ran it up to 140 (indicated) and she pulled HARD all the way though. It pulled with the same torque all the way from 80 until about 138. At that point it started backing off a little, but not much. I let go of the grip and slowed down for the next turn.

140, or whatever it really was, happened in a BLINK!

SpiderTex · 02-15-2006

Quote:

On 2006-02-13 10:01, Bel wrote:
Has this affected your speedo? I think the speedo is driven by the gearbox and reads to high when the sprocket is changed? Or has the speed per revs come down proportionately?

BEL

not gearbox, but little rotary thing on the front wheel axle

02-20-2006

This thread is based on the 1050 ST. The Speedo is definitely rear wheel driven - if you put the bike on its main stand and put it in gear with the engine running the Speedo starts to register your road speed.

This means that although acceleration etc improves, the Speedo will still show the speed based on the old sprocket ratio.

So when SR1 was accelerating quicker up to an indicated 140mph, it was probably nearer 130mph.

Does anyone know a way around this issue? I would love to do this mod but my Speedo is already about 10% fast and this will just compound it.

BEL

SR1 · 02-20-2006

Bel, you are so right.

Now, I haven't gone looking for a speedo pickup, so I will take your (Bel's) word that it is on the rear tire, which is a problem for sure. I don't think changing the sprocket will compound the problem, as the sprocket really only affects the rpms, not the speed at which the rear tire travels.

Now, for a real-world report on speedo inaccuracy, I had my 1050 up to an INDICATED 150mph last week and I brought my GPS along. It registered a 132mph top speed. that's a 12% error. It's important to realize that the 12" error is not 12% all the way from 0 to 150mph. It's somewhat logarithmic. Your error at 1 mph is tiny. Your error at 30 mph may be only 1.5 mpm not the 3.6 that 12% would suggest. What would change the reading properly would be to move the pick-up outward on the rim slightly...I think. Anyone? Can this easily be done? We would have to move it so that the new position would report a 10-12% lower speed. Hmm..