Help the noob choose sprockets

[Chaka]

Hi Guys

Jacques here from Cape Town, South Africa. Bought a '81 (I think) GSX750 few months back. This is my first bike ever and was pretty stressed learning to ride on such a 'big' bike. That feeling did not last long. Now I can't wait for winter with the rain and gail force winds to go away so I can get more riding done!!

Raining a lot here lately and lost of rain splashed up under the cover leaving a dirty chain and rust spot or two between the teeth. I 'cleaned' it for now by almost emptying a can of Win Penn on it, trying to get the oil to penetrate everywhere - just until the weekend when I can take the chain off for proper cleaning etc. That's when I noticed a stiff link.

Not sure if I can do anything to fix that and have no idea how old the chain and sprockets are. Suppose a new chain and sprockets are the best way to go?

Noticed a 41 engraved on the rear sprocket. If I recall thats the stock setup with a 15 in front.

I see guys talking about lowering revs etc using different combinations eg: 17/4? etc.
Any recommendations what to get and what the pro/cons are?

Or should I just stay with the 15/41 setup?
If I change the sprocket setup, how will this affect the chain? Will the number of links be more/less?

Apologies if the questions sounds stupid, but I still need to be educated and seems this forum is the best place for that!

Thanks in advance!
Jacques

[Chaka]

Hi Guys.
Any suggestions?
Went through old posts. Saw guys asking similar questions but could not come to a good conclusion.

If I were to change the sprockets to 17/47 (is that the correct combination), will this mean lower RPM? But what else, will this help for fuel consumption and what negative effect will this have if any?

So any suggestions will be greatly appreciated whether to stay stock or not.

[mriddle]

Welcome to the forum ..

Do you want better fuel economy ?

From what I read, most people stay close to stock.

If you are looking for a faster takeoff, you can put on a larger rear (or smaller front). This will make rpm higher at a given road speed.

Doing opposite is to put a smaller rear (or larger front) sprocket on. This will make engine rpm be lower at a given road speed. It also reduces the rate of acceleration compared to stock.

Another common replacement I read is to convert to a more narrow 530 series chain and sprockets (since you are replacing all three). They are strong enough for your bike and somewhat less costly.

[Steve]

If I were to change the sprockets to 17/47 (is that the correct combination), will this mean lower RPM?

Let's do the math:
41 divided by 15 is 2.7333
47 divided by 17 is 2.7647

The numbers are so close, you won't even notice the difference. At the speed where you run 4,000 rpm now, you would then turn 3,955. Not worth the effort.

If you were to leave the 41 on the rear, but put a 16 on the front, you would drop rpm to 3750.
If you were to leave the 41 on the rear, but put a 17 on the front, you would drop rpm to 3530.

These engines were designed to spin. The torque band hits considerably higher than 4,000 rpm, so you don't want to get too far from that or you will be down-shifting a lot just to have enough power to get down the road. If you do a lot of freeway-type riding at speeds of 60-80 mph, you might get by with the 16/41 combo, but I think the 17/41 would have you shifting a lot. If you do more backroad-type riding with curves and hills, you want to keep the engine in the range where it will make enough power to keep you moving, so you would be better off stock.

By the way, if you do go with the 530 chain conversion, you don't want to keep the same number of teeth on the sprockets. Because the links are shorter, a sprocket with the same number of teeth will have a smaller diameter, which will drag the chain on parts that shouldn't be dragged.


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[Chaka]

Thanks Guys.

Riding will be both freeway and town traffic to the office. It's about 30km freeway (limits are 100 and 120km/h on various routes, but realistically 130 km/h) with another 7km through traffic.

Was looking at better fuel economy, but looking at the math as Steve suggested make me think I should just leave things stock. Riding more behaved will give the desired results anyway