520 Offset sprockets

[salty_monk]

Anyone have any good sources? Might be needing one...

Dan

[rapidray]

How much offset do you need Dan? Ray.

[jwhelan65]

Katman did my 520 offset, pictured here with the stock spline spacer

[salty_monk]

Not sure I need any yet... but I might.

I have one of the 520/530 conversion sprockets with the extra 2mm lump on one side & I might be able to space it out enough with that. I believe I can go another 6mm spacer behind that.
If I do need an offset then it would probably be 1/4 - 1/2" max.

Dan

[rapidray]

3/8 & 5/8 are standard offsets in the dragbike world but 520 isn't. I can get 520 custom made but unsure of pricing. If Katman has some I would go that way. The one in the picture above looks like a production piece he got somewhere so I would ask him where he got it. Ray.

[salty_monk]

Kosman does them I think... have my eye one one. Not cheap though. Hopefully I can manage without, hope so.

Dan

[GregT]

You realise you can narrow a 530 offset sprocket to suit 520 ?
You've got the choice of which side to machine also for more/less offset.

Greg T

[salty_monk]

I thought the teeth were shaped?

I can easily get one ground down flat on one side to make the 1/4" thickness on a table grinder if that's all it takes...

Dan

[Billy Ricks]

Katman took care of a 3/8" offset 520 with 17 teeth for me.

[jwhelan65]

Katman took care of a 3/8" offset 520 with 17 teeth for me.

That is what is in the photo above..

[trippivot]

sprocket specialists make them 17 18 19 in many offsets with or without a bearing nose holder. spline is the same as a zx1100 D
cost is just over $100.00 highest quality

[salty_monk]

Billy, that's the offset you needed with the 160? What clearance do you have between chain & frame & wheel & frame?

Should help to double check my measurements.

Cheers,

Dan

[GregT]

Sorry for the delayed answer - yes the teeth are shaped but if you can eyeball the untouched side & copy the curve onto the side you cut back it's not a problem.Just deburr everything with a small round file before rehardening.
I'm buying 530 sprockets and narowing them for 520/525 chain pretty often as the aftermarket 530's are cheaper and available in more sizes.
And for the motors I'm building 530 is often the only width available here.
I soften them before machining - just heat to cherry red & allow to cool in air. To reharden heat again and quench in oil
I use a small lathe and carbide tips but most of the sprockets machine well after softening.
I narrow rears too but these generally are not hardened so are much easier.

Hope this can save you some $$

Greg T

[salty_monk]

Greg - thanks for the info. Interesting stuff. Definitely a money saver if you have a lathe.

Out of interest - how are the offset sprockets measured? For example is a 5/8" offset the equaivalent of having a 5/8" spacer behind a flat sprocket or is it measured from the flat on the spline side to Tooth centre or what? From the picture above it appears to be the first suggestion.

Measured it up with clamped straight edges today. Clamped one on the sprocket & another vertical at the shaft end to get the point where it met.

Seems I need 7mm spacer behind the sprocket & will have 6mm of spline contact. Will need to thin the nut down to get more threads through but it has 3mm of non threaded shoulder on the back & that's all I need. This is using a PBI 530/520 Conversion sprocket (which is 9mm wide with 9mm of spline) reversed so the "lump" is on the inside. On the flat side the splines have a shoulder or "lead" (presumably to help you line it up easily on the shaft or perhaps to aid manufacturing). The "lead" is 2mm so I actually only lose 1mm of spline contact & have a full 6mm (same as the flat JT sprocket I also have on the shelf).

That gives me 5.5mm of clearance at the frame & about 6mm to the 170 tyre.

Looks like it's all going to come good, well happy with that.

I do have a different sprocket carrier that would move sprockets inboard by 3mm but didn't want to go that close to the tyre. I could if really necessary work the spacers out so that it could move it only 1 or 2mm inboard & also have the option of buying the DID ERV3 Chain which will gain me 0.75mm each side.
Currently I have choice of 2 chains - RK X ring (20mm wide at the pins) or RK XW ring which is 21mm wide at the pins. Seems like either should work ok..

Clearances above quoted with 20mm chain width.

Dan

[GregT]

I've always taken the offset to be centerline/centerline.

I seem to be willing to run chains closer to the tyre than most here.
I regard 2 mm clearance as acceptable for a race bike.

Greg T