1980 GS 750E front sprocket 530 question.

[alhntr]

Ok the front sprocket that was not on the bike when I got it Was the 630 setup. ( was inside the cover loose ) It is 15t but it is a Sunstar sprocket that has a 6mm shoulder on it . The 16t 530 sprocket I got from Z1 has no shoulder. I have to put 1.5 mm washer on the inboard side, then sprocket and 6mm spacer to cover up all the splines......this is probably not correct ? Will it line to rear sprocket fine ?Or do need to order a sprocket that has the shoulder and still use 6mm spacer on outboard side. I'm doing the 530 set up. Thanks

[Rich82GS750TZ]

Spacer should go outboard of the sprocket. I went through this.

https://www.thegsresources.com/_forum/forum/technical-forums/-4-cylinder-engine-drivetrain-clutch/90411-chain-missing-an-o-ring

[alhntr]

Yeah I get the 6mm goes on outboard side, so went sprocket, 6mm spacer then 1.5 mm washer and serrated lock washer to get all the splines cover so main nut can tighten.

[Rich82GS750TZ]

Just be sure of your alignment once you get everything buttoned up. I used a cheap laser from harbor freight that I happened to have in my ever growing pile of tools. They come in handy for all sorts of home projects.

[alhntr]

I ordered one of those motion pro alignment tool, should be here next day or two. Laser good idea too.

[Nessism]

The stock sprocket is a 15T 630, so when moving to 530 it's important to increase THREE teeth, in order to maintain the same diameter as original.

15T 630 = 18T 530

Stock ratio = 41/15 = 2.73

18 x 2.73 = 49T rear 530 sprocket

96 link 630 chain = 96 x 6/8 = 72" long chain

For 530, 72 / 5/8 = 15.2 (use 116 link 530 chain)

[Rich82GS750TZ]

Alhntr, just to re-state what Ed wrote above. If you keep that 15 tooth front sprocket, what is your rear sprocket? Seems like you would be drastically changing the drive ration from stock.

The 18/49 530 works out to a drive ratio of 2.722, which is as close you can get to the original drive ratio of 2.733 with the 15/41 630.

Chain Calculator

630 (6 eighths = .75)


530 (5 eighths = .625)

[alhntr]

Rich, Z1 Enterprises sold me a 16T front and a 45 rear, final ratio close and said a 530 112 link would work. That was their recommendation. So I bought a 112T chain. Hope I did not just screw myself. Or maybe they just wanted to sell the parts they had in stock. I asked about the 18/49 and they came with above mentioned.

[Rich82GS750TZ]

That should work. I think you’ll likely have a bit quicker acceleration at the expense of lower top end speed. But I’m no expert.

[alhntr]

Yeah he said 100 rpm difference, you guys rock

[rphillips]

What you got won't be stock, but hardly enough for most to notice. A 44 rear would have got you slightly closer, but think you'll be good as far as gearing, no clue about # of links.

[KiwiAlfa156]

I did a 630 - 520 conversion recently on my 750. https://www.thegsresources.com/_foru...sprocket/page2
There are some sprocket size comparison photos you might find interesting.

I installed 17T/47T and here's what I learnt.

• While the formula spits out 18T front, a 17T works with no issues on a GS/GSX with an alloy arm
• Even a small deviation in overall ratio from the 15/41 2.7333 ratio will have a slight but noticeable effect.

My options were:

- 47T rear would yield a slightly lower 2.76.
- 46T rear would yield a slightly higher = 2.7
- 48T = 2.83:1 (close to the 1100 std ratio of 2.8)

At 7.6:1 final drive, the rpm at 100 kph (62 mph) is close to 5,000 rpm - bit higher than stock. I don't have a problem with this.

• Modern 520 chain is more than strong enough for an 80s 750 output. After the initial break in, one minor adjustment required after 6,000 mi (and I don't cruise about). I fitted an RK 520XSO2 RX-Ring

-Tensile Strength: 36.5 Kn
-Weight/100 links: 1.56kg
-Max CC Rating: 800cc

• Why a 520 than a 530? All the advantages of a 530 over a 630 but more.

[alhntr]

Good info, the rear sprocket was on on close out only 10 bucks and they sent me two of them like have another on us. But yeah down the road get a 44T would be an option..