520 rear sprocket and drum.

Where's the best place to get the machined for 520 chain, rear sprocket/brake drum, in North America?

they are sold here
http://www.clubmanracing.com/chainssprockets.php
I also think CNW carries them

Better to start with a new 520 sprocket/drum. Send it and backing plate to Vintage Brake first. “Mercury” Morse is a magician with brakes. You will be amazed how well the Commando rear drum can perform with the right setup.

http://www.vintagebrake.com/

Above drum advice is likely better way to go as 530 drum teeth need machined from left faces to .240" but removed hard surface so wears faster. Atlas 520 tranny sprockets are bolt on item to solve that part. I did 520 conversion on both a Combat and SV650, to hardly notice any performance benefit but sure noticed the drum and sprocket and chain vendors liked it a lot better than I. Should pay extra attention not to let chain get much slack in links, measured by how far out of valleys can lift out on back side of drum - as that is where the links will bare on the teeth riding, which tends to wear teeth to points then bend over or crack off till just nubbins left the chain slides across making noise going no where. I quit 520 upgrade about a decade ago.

I thought the advantage of using a 520 chain was the ability to fit an o-ring chain and they are "supposed" to last longer than a non o-ring 530.

olbbeezer said:

I thought the advantage of using a 520 chain was the ability to fit an o-ring chain and they are "supposed" to last longer than a non o-ring 530.

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That is the case. Much longer chain and sprocket life running an “O” or “X” ring chain. Maybe not so in Arkansas.

520 counter and final drive sprockets are readily available, not real expensive either, probably the same price as their 530 counterparts (no pun intended). The part most people forget is to space the 520 counter sprocket 1/16" off the transmission so that the chain run is true; the spacer is key; you might get away with grinding off an 1/8th from the inside of a 530 counter shaft sprocket and final drive sprocket, I can't say.

You can have the standard sprockets ground, but it is not as straight forward as knocking off a 1/16" on each side, there are at least two angles involved and a bit of judgment; new parts are manufactured, doesn't mean they are perfect, but means that the manufacturer has too much invested to make a poor set-up, so your chances of a V 1.0 fit are near 100%. Cutting down 530 parts may remove hardening, but I don't know enough about how they are made to say, but this forum, however, has plenty of members who know metallurgy and may chime in.

An X or O ring chain will out last several non sealed chains with less maintenance which means that you won't be replacing sprockets nearly as often, a virtual buy back There was some buzz about sealed chains eating more power, which makes sense, but you can most likely get tat power back by loosing 5 pounds of body weight, ' can't say.

In most cases a X-ring 530 will fit, though some might foul AMC bottom bearing bugle for a few miles till silent there after. O-ring = Obsolete to me as distinctly stiffer compared, if ya have ya durthers but sealed literally beats snot out of external lubed mess makers.

As for a sealed 520 chain out lasting a dry plain chain, both will ride mid way up valleys in about 10K miles about regardless of how easy or harsh their are collected. Only way to lube enough external is enough that gets thrown off as past late great daily British users had to do and why Nortons all had factory drip oils all set for effective sling off everyone now blocks or removes.

Chain study for industry found lubrication for friction was essentially nil, as roller/links are not moving much and narrow slow load bearing contacts press all lube out for metal/metal contract, so only the metal flake flush out mattered by preventing ceramic like grinding paste accumulating.

hobot solution is buy a roll of 530 plain chain, run dry or power wash off, to slice off a new length when its links get ~1/3 lift out valleys as easier that dealling with new drum teeth. Wesley got two chain changes off the roll I picked up at a rally swap meet he'd led me too. Lasts ~ 8k miles & two rear tires in THE Grity Ozark travel.

i have been running the 520 conversion for years with great success. i get over 25,000 miles on the chain and sprockets. the parts are readily available from several sources as the front is an early dommi part and the rear is an easily machined rear drum.

Duly noted. Same here.

bill said:

i have been running the 520 conversion for years with great success. i get over 25,000 miles on the chain and sprockets. the parts are readily available from several sources as the front is an early dommi part and the rear is an easily machined rear drum.

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oldbeezer said:

they are sold here
http://www.clubmanracing.com/chainssprockets.php
I also think CNW carries them

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Clubman Racing isn't responding to phone or email.

CNW does not list the drum separately.

I bought CNW's 520 chain conversion kit and it's been on the bike since '08; nothing but praise and the same chain is still there at 28k miles.