Sprocket and chain to lower RPM's at 70 on a 550l

[Black 550 L]

I would like to lower the rpms on a 1980 gs 550 L from 5900 at 70 to about 5000. What chain and sprockets would you recommend to do this or is this something I should even consider doing.

[Nessism]

GS550E runs lower rpm at freeway speeds than the L model because the rear wheel is larger, so it should be fine for you to do it through sprocket gearing. Dropping 900 rpm at 70 mph is not very realistic though. Simple thing to do is go up one tooth on your front sprocket - this will drop the rpm by about 300 rpm or something near. You can also drop the rear sprocket size by a couple of teeth if you want more of an overdrive. Pretty easy change.

[J_C]

Try calling Z1 enterprises. I spoke to a guy on the phone just yesterday to order a new chain and sprockets. I ended up doing a 630 to 530 chain conversion, and we (he) calculated out some drive ratios on the phone to get me a slightly lower rpm on the freeway. Great experience.

[Nessism]

It's pretty easy calculating rpm reductions when changing sprockets.

Stock gearing for a 1980 GS550L: 15T front and 51T rear.

Stock bike runs 5900 rpm at 70 mph (as stated)

If you changed up to a 16 T front the new speed would be 5900 x 15/16 = 5531 rpm

Now if you went to a 49 rear it would be 5531 x 49/51 = 5214 rpm

Understand that when the gearing is changed like this the bike will require more clutch slipping to get off the line and the top gear acceleration will be less.

Good luck.

[posplayr]

JC I'm right behind you

I guess I need to go count the links on my existing chain. I got the wrong valve cover gasket from APE, so I will order gaskets and conversion from Z1.

Who did you speak to? Did you get an O-ring chain? Which one?

Posplayr

[J_C]

I spoke to Jeff @ z1. I think I got the RK X ring chain (x is better than o from the marketing material I've read )