New sprockets + cold tyres + no slipper clutch = …

[325rocket]

Full pants that’s what.

Exciting day wednesday.
I got home to find my new front and rear sprockets had arrived, so down to the garage and on they went.
I went for a 15t front (one down from standard) and a 45t rear (up 4). I only wanted the front but I was offered the rear at a good price so decided what the hell it should be a laugh.

The first ride was pretty funny with the bike lifting the wheel at crazy (indicated) speeds. The speedo was way out due to the different gearing but its still a buzz to have the bike so responsive at these indicated speeds. The other big difference I noticed was due to the rear wheel having to be moved right up the swing arm. It felt like it would just drop into corners and was pretty unstable at slow speed. I couldn’t get used to this at all but im sure it would be different at higher speed.

Day 2 … home from work and wanted to go for a ride.
You know how sometimes you feel like you really are the master of your machine and where you want it to go it will go … inch perfect.
This state of mind really encourages you to ride aggressively and give it to it a little more then you normally would. These are the days you really gel with your bike.
Well yesterday felt like one of those days. So after warming my bike up off I went. At the end of my road theres an intersection so I stopped to give way. Rite, all clear turn right and give it a handful. First, second, third. Due to the gearing im not going all that fast but I need to chop it back to second for the right hander that’s coming up.
Down into second … what the hell was that??? Back tyre locked up and snaking all over the road (for about 20 meters) … clutch in and back out a little slower … same thing. All I could do was free wheel around the corner with the clutch in and hope for the best. Target fixation is a bitch and nearly cost me but in the end all was ok.

Thinking back I should have put it in third but at the time it all happened pretty fast.

So, lessons are

1. don’t go crazy with cold tyres.
2. if you change anything on your bike give yourself time to get used to it.
3. try to keep calm when it all turns to shit. Hard to do but a good idea if you can.

Needless to say the rear is back to standard and the bike is yet to be ridden … with warm tyres.

and yes i know "you shouldnt need a slipper clutch for general road riding" ... would have been nice on thursday though.

[MentalFacility]

I just had a new tyre installed yesterday. And I went for a ride today, in about first 10 minutes, turning right, at around 70km\h I've had one MEAN drift. Almost as mean as getting a pair of new underware.

Just have to be more carefull in the corners, but after only about 150 km I've managed to get it all polished almost up to the edge. Still is a bit slippery tho.

Sprockets... Dont really think its any good to change them unless you plan to go the track often, or you do stunts.

[R6_kid]

Sprockets... Dont really think its any good to change them unless you plan to go the track often, or you do stunts.

So you do 300kmh often then?

[Mikkel]

Hmm, I'm surprised that the bike reads the speed of the rear-wheel. It's usually taken of the front wheel...

[MentalFacility]

So you do 300kmh often then?

No I dont.

[vifferman]

Hmm, I'm surprised that the bike reads the speed of the rear-wheel. It's usually taken of the front wheel...
On many bikes (like mine) there's a drive off the countershaft sprocket or gearbox, which sends electrical impluses to the speedo. Change the gearing = change the speedo reading.

Changing the gearing by one tooth on the front sprocket or up to 5 on the rear is common, and useful unless most of your riding is touring. I would've thought though that doing both was a bit OTT: -1 and +4 is what? about -12%?
I went down 1 on the front sprocket on the last three bikes and that was around 6% lower gearing - great for communtering, and excellent on the FahrtSturm for poking the revs in 6th up a bit (2600 at 100km/h was ridiculous, and below where the torque wodge kicked in.)

[LBD]

I have fitted a slipper to my new S4Rs duc after having had numerous rear end lockups with my S4.

Doesn't that make a difference...My fav road has a couple of bends where the slipper is very noticable. One, a down hill over a crest to the right braking for a one lane bridge was particularly bad if I was in a hurry. It is now nice and smooth.

Ratio's? Don't settle for one ratio for all. My advise is to experiment, I find having the right ratio on a fav road, or on a track, it makes the ride so much more fun, less changes, smoother, faster.

[325rocket]

I would've thought though that doing both was a bit OTT: -1 and +4 is what? about -12%?


yeah it was way over the top haha but it was there.
did you install a speedo healer (or similar) or just guess your speed now?

[zx rider]

Hi 325rocket. I fear you may have fallen into a little trap with your gearing. You now have a final drive ratio of 3 to 1 (exactly) which means the chain will wear out your sprockets much quicker than an odd numbered ratio (eg. 2.90 to 1). This happens because the tight and slack sections within the chain will always be working on the same contacted areas of the teeth. You will have to be vigorous with your maintainance of these parts but even then their life will be shortened quite a lot. Sorry if this takes the shine of your fun.

[325rocket]

Hi 325rocket. I fear you may have fallen into a little trap with your gearing. You now have a final drive ratio of 3 to 1 (exactly) which means the chain will wear out your sprockets much quicker than an odd numbered ratio (eg. 2.90 to 1). This happens because the tight and slack sections within the chain will always be working on the same contacted areas of the teeth. You will have to be vigorous with your maintainance of these parts but even then their life will be shortened quite a lot. Sorry if this takes the shine of your fun.

not at all, thanks for the advise.
ive gone back to standard at the rear so i guess ill be ok now?

[Max Preload]

I went for a 15t front (one down from standard) and a 45t rear (up 4). I only wanted the front but I was offered the rear at a good price so decided what the hell it should be a laugh.

15% is a massive final drive ratio change.


Hi 325rocket. I fear you may have fallen into a little trap with your gearing. You now have a final drive ratio of 3 to 1 (exactly) which means the chain will wear out your sprockets much quicker than an odd numbered ratio (eg. 2.90 to 1). This happens because the tight and slack sections within the chain will always be working on the same contacted areas of the teeth. You will have to be vigorous with your maintainance of these parts but even then their life will be shortened quite a lot. Sorry if this takes the shine of your fun.

Not quite. What you've said is true in the case of gears meshing, but not chain transmission. It depends on how many links are on the chain. While the ratio is the same the number of links on the chain will determine the frequency of repeat contact of the same roller on the chain with the same sprocket tooth.

For example, 3 revolutions of a rear sprocket with 45 teeth with a chain of 106 pins will be 2.355 revolutions of the rear sprocket to one revolution of the chain. At the same time the front sprocket of 15 teeth will have done 7.066 revolutions.

[discotex]

did you install a speedo healer (or similar) or just guess your speed now?

Guessing speeds is good but don't forget you'll be clocking up km on the odometer quicker as well.

[MarkH]

First, second, third. Due to the gearing im not going all that fast but I need to chop it back to second for the right hander that’s coming up.
Down into second … what the hell was that??? Back tyre locked up and snaking all over the road (for about 20 meters) … clutch in and back out a little slower … same thing. All I could do was free wheel around the corner with the clutch in and hope for the best.

I'm no expert, so I could be wrong here:
If you locked in 2nd then surely 2nd was too low, did you consider changing back into 3rd? i.e. instead of free wheeling around the corner with the clutch in you could have tried coming into the corner in 3rd with the throttle off and then opened the throttle as you exited.

Or is there some reason you can't throttle off for a corner without changing down a gear? Or did you assume you needed 2nd for the corner since that was the right gear before you changed your sprockets? Maybe what was once a 2nd gear corner is now a 3rd gear corner with your new gearing.

[Chrislost]

Hmm, I'm surprised that the bike reads the speed of the rear-wheel. It's usually taken of the front wheel...

what?
almost every japsports bike will read from the front SPROCKET.
same difference as the back wheel.

i cant wait for somone with ABS to change their gearing, that willl fuck it!

[Max Preload]

I cant wait for somone with ABS to change their gearing, that willl fuck it!

Ummmm, no. The angular velocity of the wheel is taken from a hall effect sensor on the wheel. I've never heard of one working off the speedometer.

[Duc]

@ the OP (325rocket)

I get the impression you dont ride so well from your description of what happened. It seems to me that you had no "feel " for your machine and got caught out by basic gear selection then resorted to freewheeling thru a corner. (Maybe on the brakes as well due to panic!)

Despite the high performance spec of your bike I doubt that it has engine braking like you would find in a V-Twin for example. Your gearing mods would not have made that much difference to engine braking so I would think you just came in far too hot and dropped to an unneccessarily low gear through lack of feel.

[325rocket]

I'm no expert, so I could be wrong here:
If you locked in 2nd then surely 2nd was too low, did you consider changing back into 3rd? i.e. instead of free wheeling around the corner with the clutch in you could have tried coming into the corner in 3rd with the throttle off and then opened the throttle as you exited.

Or is there some reason you can't throttle off for a corner without changing down a gear? Or did you assume you needed 2nd for the corner since that was the right gear before you changed your sprockets? Maybe what was once a 2nd gear corner is now a 3rd gear corner with your new gearing.

thats it at the end. it was now a 3rd gear corner.




I get the impression you dont ride so well from your description of what happened. It seems to me that you had no "feel " for your machine and got caught out by basic gear selection then resorted to freewheeling thru a corner. (Maybe on the brakes as well due to panic!)

no, no brakes. to be honest it was such a stupid mistake i was laughing my head off at the time. the road is a known shit, no grip kind of road covered in overbanding. tyres were stone cold. stupid stupid mistake. i had a heap of feel for what was going on and i knew it wasnt going to be a major due to an ok run off area.



Despite the high performance spec of your bike I doubt that it has engine braking like you would find in a V-Twin for example.

no but it does have a surprising amount for an il4.



Your gearing mods would not have made that much difference to engine braking
but it made a hell of difference to take off speed.



so I would think you just came in far too hot and dropped to an unneccessarily low gear

yep.

[Weta]

Yes I've recently bought a K3 Gixer which I'm pretty sure is 1 diff on front as the speedos about 20km/h out, bit of a pain around town and guessing on the motorways a bit interesting, can't imajine the cops will be sympathetic. Is there an easy fix for this?

[325rocket]

try Speedo Healer (http://www.healtech-electronics.com/) its the way to go i think

[steelestring]

Hey man good to hear you handled the sprocket change! Kinda interested in changing my sprockets also :whistle: My only justification is a bit more get up and go and shiney new sprocket bling.... I didnt know the speedo was going to be affected so dramatically. Have you found a supplier in nz yet for the healer?

[325rocket]

hey,

i didnt need to. i changed it back to standard in the end.
if you email the guys at Power Sport (http://www.powersport.co.nz/) they seem to be able to get hold of anything you need.