sprockets

[zedrider]

hi there some advise please . my drive chain is worn out so it would seam a good time to change the sprocekts too . i have a 1000 ltd american import . when i take the bike above say 80mph shes reving her nuts off . shes still got lots in reserve . but i would like to gear her up so the revs arent so high the chain pitch is 630 the rear sprocket has 33 teath ive read it should be nearer 39? i dont know what the frount one is as yet . any ideas what i should be looking for ? many thanks ian

[paulmceleney]

smaller rear or larger front

[Garn 1]

Zedrider, look up the specs for your model Z1000 Ltd. and find out what sprocket sizes were standard. Also take notice of the size of the rear wheel. I think some or all Z1000 Ltd had a 16'' rear wheel, giving a lower ratio.

To interpret and help you, the forum would need to know......
Size of front sprocker = [---------]?
Size of rear sprocket = 33 Teeth (given)
Size of rear wheel = [-----------]? (usually 16" or 18").
Type of chain = 630 (given).
Requirement = lower revs in top gear at 80 mph.

Fill in the blanks and I'm sure an expert will tell you exactly what you need.

RegardZ.

[steve bowdler]

Hi mate try this http://www.jtsprockets.com/52.0.html?&L=0 always find these very helpful

[zedrider]

Zedrider, look up the specs for your model Z1000 Ltd. and find out what sprocket sizes were standard. Also take notice of the size of the rear wheel. I think some or all Z1000 Ltd had a 16'' rear wheel, giving a lower ratio.

To interpret and help you, the forum would need to know......
Size of front sprocker = [15]
Size of rear sprocket = 33 Teeth (given)
Size of rear wheel = [16] (usually 16" or 18").
Type of chain = 630 (given).
Requirement = lower revs in top gear at 80 mph.

Fill in the blanks and I'm sure an expert will tell you exactly what you need.

RegardZ.

[Garn 1]

Firstly, using the "JT Sprocket" site, suggested by SteveB.
Enter "Kawasaki KZ1000", you will find this.... KZ1000 model B1/ B2/ B3/B4 (LTD) USA 77-81.
On entering, you will see this model only suggest one size of front sprocket, which is what you have [15 teeth]. A 16 tooth would probably fit, however, it is not mentioned.

It then gives you a list of rear sprockets and their ratios.
To reduce revs in top gear for a given speed (MPH), you would, as PaulMc' mentions ..... have to have a smaller rear sprocket.
Now, the lists states the smallest is 32 teeth, this is probably due to hub limitations. However, it could just make the difference. The same chain length (92 links) as existing would suffice. The ratio change is from 2.20 to 2.13.

The only other way to alter this ratio significatly, is to see if a 16 tooth front sprocker would fit, leaving the 33 T rear in place.
BTW, I'm no expert
RegardZ

[debben1]

Calculator ready and you can work out much rpm/mph

At 1000 rpm the front sprocket turns at 474.22681 rpm
stock reduction ratio 15/33 is 2.2 so the wheel at 1000rpm is turning at
215.55764
Circumference of the rear 16" wheel (406.4mm) with 130/90 tyre ?? (90% of 130mm= 117 x 2) gives a diameter of 640.4 mm
640 x 3.14 = 2009.6mm
(The 16 inch narrower wheel with a higher profile tyre has a bigger diameter than a 17" wider wheel with a lower profile tyre)

Wheel speed of 215.55764 per minute travels 433'184.63 milimetres a minute, or 25'991'077 an hour, there are
1609344 milimeters in a mile so divide 25'999'077 by 1609344 and you have 16.150106 miles an hour for every 1000rpm on a stock set up

This figure will give you an acurate mph to rpm for stock gearing
4900 rpm (4.9 x 16.150106) = 80 (mph)
Therefore your bike is only revving at 4900 rpm at 80 mph, maybe half its maximum rpm, at 10'000rpm given enough power to pull this already quite high gearing would be able to pull 10 x 16.150106 which is 161 mph


16/33= 2.0625
This would change your mph per 1000rpm to 17.22678
4'900 rpm would = 84.4mph
8'000 rpm = 137.8mph
10'000 rpm = 172 mph

Could it be clutch slip that is letting the bike rev ?
Regards, Steve

[PJ]

Wow Steve - you lost me at calculator ready

[debben1]

I missed out the complete calculation

Primary reduction ratio is 56/97 = 1.7321428
5th gear reduction ratio is 23/28 =1.2173913
Final reduction ratio is 15/33 = 2.2
Overall rreductio ratio = 4.64
Terefore
Cranks spinning at 1000 rpm then the clutch and input shaft are spinning at 577.3196
Input shaft at 577.3196 then in top gear the output shaft and front sprocket is spinning at 474.22681

I edited it so that i didnt send everyone too sleep , opps to late, i have bored you all to sleep

[zedrider]

hi thankyou for the welth of information here . hi steve thanks for the clever stuff . if anything the clutch is heavy the cable is well lubed and runnin freely . but she just feels heavy . maybe if i do what i did for my z650 . IE redline cluch plates and heavy duty springs would make that feel better . but the cluch i would say is working corectly . pitty i dont have a club member liveing close by who could try it and help work out whats going on . ian

[Rich]

Change up a gear Joking aside what size rear tyre do you have and what revs are "revving its' nuts off"

[zedrider]

update . i went for a standard 15 teath on the front , and 39 on the rear . now goes like a bat out of hell . all i need to do now is put in some new rear wheel bearings .