520 Sprocket 530 Chain?

[NotadenBennettii]

Hello All,

I have an '88 model GR650 (Tempter) and am wanting to make it more suitable for highway speeds.
It has no trouble doing those speeds with the stock sprockets but when doing so the revs are fairly high and right at the point where engine vibration becomes annoying.
Stock sizes are 38 rear, 15 front.
I've been unable to source a smaller rear, I believe 36 was used when these bikes were popular but I can't find one anywhere.
I did manage to find a 16 tooth front that is currently on it and does help somewhat with lowering the revs at highway speeds.
However it's a 520 that's made for a GN400, whereas the rear sprocket and chain are 530.

I'm about to replace the chain with an x-ring 530, currently an o-ring 530.
Any issues with doing that or running a 520 front with a 530 chain and rear that anyone knows about?
Had no issues so far for about 1500 km's.

Thanks



EDIT: better include a pic

EDIT2: does anyone know of a smaller rear sprocket from a different bike that might fit?

 

[Shinyribs]

I can see that it would damage itself in any way. It's only an 1/8 difference in width, so not a huge mismatch. If there's ample room to not worthy about getting getting tangled up on the engine case, I wouldn't worry about it.

 

[Alan F.]

One of my unfinished projects is using a 525 chain & rear sprocket with a 520 front sprocket, I searched and searched before making the decision and only found a few references. The one that put me over the top was a guy who bought a used Vstrom 650, PO had just changed chain & sprockets and had the receipts. 6 years later the guy decided it was time to replace and found a size mismatch. He never had one indication of a problem, and had ridden it hard like a Vstrom can handle. After that I ordered up a $19 DID non-o-ring chain figuring if I liked it I could get an O or X-ring later on.

Cheers.

 

[NotadenBennettii]

Thanks for the info, I'll keep using it as it is.
I might do some research for the specs of the bolt holes on the rear sprocket one of these days to see if I can find a smaller one that'll fit ok.
Plenty of stock and larger ones up to 50 or more teeth but nothing smaller so far that I've found.

 

[Shinyribs]

I can see that it would damage itself in any way. It's only an 1/8 difference in width, so not a huge mismatch. If there's ample room to not worthy about getting getting tangled up on the engine case, I wouldn't worry about it.

Supposed to say

I CAN'T see that it would damage itself...

and

room to not WORRY about hitting the case.

Apparently I was drunk typing. 🤦

 

[NotadenBennettii]

LOL, all good

 

[Alan F.]

JTSprockets.com catalog has nice measured drawings of their sprockets

 

[Shinyribs]

JTSprockets.com catalog has nice measured drawings of their sprockets

Incase some folks don't know, all sprocket dimensions represents 1/8's of an inch.

500 series chains are 5/8" between pins, 600 series chain are 6/8" between pins, etc.

The last two numbers denote width.
20= 2/8
30= 3/8

And yeah, 25= 2.5/8, which is kinda weird, but it works.

525 chain will be 5/8" pin to pin and made to ride on a sprocket tooth that is two and a half eighth's, or 5/16" wide.

With that in mind you can see that a 530 chain running on a 520 sprocket is is only running 1/16" extra clearance on each side, most likely a non issue for a front sprocket. Maybe it'd wander around some on a large rear sprocket, but I doubt that you'd know it.

 

[Oldtrialer]

It will give someplace for the muck to squeeze out and not wear the sprocket.

 

[Alan F.]

It will give someplace for the muck to squeeze out and not wear the sprocket.

That sure would be a good one to test.

 

[Amos Malone]

Why not use 525 or 520 all around? Modern 520 or 525 chain is probably stronger than the 530 was 34 years ago, when your bike was made.

 

[NotadenBennettii]

If I can find a smaller rear sprocket that's 520 I will probably put a 520 chain on it.
Haven't had time to try and find one that'll fit it yet so not sure what I'll end up with.

 

[Alan F.]

Looks to me like the easiest way to get yourself a 520 sprocket would be to have 1/16" ground off of each side of a 530 sprocket by a machine shop with a surface grinder. Most engine shops will have a surface grinder for flywheels, etc. Might be worth a few phone calls.

 

[NotadenBennettii]

I'd prefer to have kept it all 530, though the only larger front sprocket I was able to find was a 16 tooth 520 made for a GN400.
If I find a smaller rear than the stock 38 tooth that fits it that happens to be a 520 then I will probably switch to a 520 chain.
If I find a smaller rear that's 530 then that's good too, I'll just use the new 530 chain I already have.
What I'm hoping is to find a small enough 530 rear that'll allow me to put the 530 front back on and still give me lower revs than stock at highway speeds...if there is such a thing I guess...bit like finding the time to look for them

 

[DJ_MI]

Incase some folks don't know, all sprocket dimensions represents 1/8's of an inch.

500 series chains are 5/8" between pins, 600 series chain are 6/8" between pins, etc.

The last two numbers denote width.
20= 2/8
30= 3/8

And yeah, 25= 2.5/8, which is kinda weird, but it works.

525 chain will be 5/8" pin to pin and made to ride on a sprocket tooth that is two and a half eighth's, or 5/16" wide.

With that in mind you can see that a 530 chain running on a 520 sprocket is is only running 1/16" extra clearance on each side, most likely a non issue for a front sprocket. Maybe it'd wander around some on a large rear sprocket, but I doubt that you'd know it.

Great info! I’d read that all 500 chains were the same pitch but didn’t know the numbers actually were measurements. 👍

 

[BergDonk]

FWIW I'm running a 520 rear sprocket with a 525 chain on one of my DRs without issue.