Sprockets

Honestly don't know if this is the right forum, please move if it isn't.

So on my kz750 im finally replacing the chain and sprockets, it had a ek630 chain with 13 & 32 tooth jt sprockets.

Converting to 530pitch 13:39 teeth and a did chain. I did this to up the acceleration but I read somewhere that changing the pitch is going to make this ratio almost the same as with the smaller 630 rear sprocket. Basically making my acceleration the same. Any truth in that statement?

If the front sprocket has 13 teeth and the rear has 39 teeth the ratio of the sprockets is 1:3 which means for every full revolution of the rear sprocket (and tire) the front sprocket will make 3 revolutions. The pitch of the chain will not affect that ratio. Ed

I found this link very useful
www.z1enterprises.com/Chain630To530.aspx

GearingCommander has at least one 750-4 loaded in their database.
Z1Enterprises.com has the 530 conversion info.
To prolong the life of the chain a larger Fr sprocket is preferable --- the stock sprocket is small.
Possible 530 setup: 16T Fr & 42T Rr. .... Or 17T Fr & 45T Rr (if a 17T will fit).
A related topic. Counter sprockets on a 1980 kz750H1

I thought it sounded odd which is why I asked, it definitely helped the acceleration, I can still top the speedometer but now at full throttle it hits 9.5k rpm instead of stopping at 8k

65mph is 6.5-7k rpm which should be fine I think...

Wow.
Steve

whirlwind598 wrote: I thought it sounded odd which is why I asked, it definitely helped the acceleration, I can still top the speedometer but now at full throttle it hits 9.5k rpm instead of stopping at 8k

65mph is 6.5-7k rpm which should be fine I think...

What? That's way too high! At that ratio your top speed at redline would only be about 85 mph! Either your clutch is slipping badly or you need to change the size of the sprockets. My KZ650 with stock 16/42 sprockets turns 4874 rpm at 65 mph. Ed

I've seen Ninja style bikes on the FWY taching that high. Stuck at 65 MPH. Out of the hole light to light quick is good for some, for me, 65 at 4000 is comfortable. Now with a 1000cc's, big carbs, 4/1 etc, I can pull out of the hole in decent time but I'm going through a tire every 4 months or so. I can imagine what it would be like with lower gearing.
Think about this, Taching at 65-7000 RPM for long stretches is wearing out the engine that much faster. Better to be a little slow on take off, than rebuilding a motor every year.
Just my opinion, yeah everyone has one, what ever turns your crank.
Steve

Whirlwind568 I'm assuming your 750 is a 4 cylinder.

Stock 630 sprockets for the 1980 740/4 are 13 front and 33 rear and an 84 link ( I think) chain.

I currently have 13 front and 37 rear and I hit 60mph (100kph) at 5,000 rpm. Take off is quite fast though.
I'll be ordering new 530 chain and sprockets in the next couple of weeks - cant do anythng with bike until March - and I intend to go back to stock type gearing which will lower the rpm at 60mph/100kph

Dividing everything by 5 and multiplying by 6 I plan to order a 16 front and a 40 tooth rear (33/5x6) and a 101 link or thereabouts chain.

If you did the 530 conversion as described in your first post but kept the front sprocket at 13 tooth then that might account for the high rpm- even higher than mine - at 60 to 65mph

650ed wrote:

whirlwind598 wrote: I thought it sounded odd which is why I asked, it definitely helped the acceleration, I can still top the speedometer but now at full throttle it hits 9.5k rpm instead of stopping at 8k

65mph is 6.5-7k rpm which should be fine I think...

What? That's way too high! At that ratio your top speed at redline would only be about 85 mph! Either your clutch is slipping badly or you need to change the size of the sprockets. My KZ650 with stock 16/42 sprockets turns 4874 rpm at 65 mph. Ed

Its definitely a higher ratio than yours, I have never been able to red line this bike, on the old ratio 13:32 I topped at 8k rpm on a straight highway, probably 95 mph at the most

I need to test it again but that'll wait til its warmer...

@JR mines an 83 h4 stock should be 13:32 with 88 links on a 630.

Speedo only goes to 85.