Confused on Sprocket conversion

[s_mike321]

Sorry guys i know this one get asked alot. I have a 1981 gs750L. 16/40 is what i have for sprockets now. I want to make the conversion to 530. If i do the math from z1 it gives me. 19/48 which there is no 19 tooth front. So i was thinking 18/48. Am i way off on this???? Any advice would be great!

[Steve]

If you wanted to keep your exact ratio, order the 18 front and get a 45 rear.

Using the 48 rear with the 18 front will increase your revs at highway speed.

.

[s_mike321]

Thanks for the input! i think i'm going to go down to a 17 in the front. Doing some searching the one 18 i found doesn't say my specific model. Where the 17 does. If i go down one in the front, that changes my torque?

[Steve]

That will give you more torque (power), but will again increase your revs at any highway speed.

Just to illustrate, whatever speed you used to go with the engine at 4000 rpm (let's just say 60 mph):
19T = 60 mph
18T = 56.8 mph
17T = 53.7 mph

or, let's show engine speed at 60 mph:
19T = 4000
18T = 4222
17T = 4470

I would suggest calling Z1 and actually talking to them, not just looking at their website.
Jeff and Chris really know what they are talking about with the GS bikes.

.

[s_mike321]

Thank you for your help!!!!!

[Suzuki_Don]

A smaller tooth sprocket on the front increases accelaration and at the same time drops the top speed. This is what Steve is saying by the figures he has produced. Talk to Z1 as suggested.

[mighty13d]

17f-42r will put you very very close to 19-48. That is providing you intend to keep it the same as it is now, and providing you did the math correctly.

[sparki]

.... and providing a 42 tooth rear sprocket, as it's quite a bit smaller, will not make the chain scrape on the swingarm pivot...

[whiterabbitt]

on my 77 750 I went as small as 16-38 without ever rubbing the swingarm pivot when I did my 530 conversion. I dont recommend it though as I lost a ton of grunt and acceleration.

[Graham]

Why do we need to go to a 530 chain over stock chain?

[mcycle-nut]

Why do we need to go to a 530 chain over stock chain?

Less weight and a better selection of chains. Just try getting a 630 chain now. You would have an easier time getting crack from your parts supplier than a 630 chain.

[OzJavelin]

on my 77 750 I went as small as 16-38 without ever rubbing the swingarm pivot when I did my 530 conversion. I dont recommend it though as I lost a ton of grunt and acceleration.

Other than the sprocket maths, anything else I'd need for 530 conversion on a 78 GS750? Spacers on front sprocket?

[cowboyup3371]

Did you talk to Z1 as suggested? What did they recommend?