My first GS "dorkbox"

[Buffalo Bill]

It's been a few years, but the power band is the same for most of the GS's, the 550 has to be allowed to rev all the way up to 8-9000 RPM. It's just that the 550 is almost the smallest, least powerful. I sold my 550 soon enough, but have kept my GS1100G as my favorite ride.
It's not the fastest of any of the 550cc bikes of it's period 77-84.
Have a look at my poll about this class size and you'll see what guys on this site voted for: Mid 80s 550cc proto sport bikes.

Nobody voted for the Kawasaki EX500, later called the Ninja 500, but it blows them all away with only 500cc. My 1st bike, but the seat was too cramped for me at 6'4".

 

[Chuck78]

The 77-82 gs550 is a fine bike that has a lot of potential. Look for a used 4-into-1 and k&n pods and get a dynojet kit for the carbs. Or just cut to the chase and swap a whole gs550 top end on it. That will REALLY wake it up. It will be far faster through twisty roads than that "Sportster" which is a funny name because they aren't sporty at all... put slightly longer rear shocks on the back of the GS, new fork seals and oil, chop several inches out of the fork springs & replace with a tubing spacer, $60 MikesXS.com cartridge emulators are a HUGE bonus to drop on while the forks are apart.

Get some good tires in no wider than stock sizes for the best handling. Avon AM26 RoadRider is a great compromise between a sport tire and a highway mileage tire. Shinko makes a 230 that is super grippy & a 712 that lasts a lot of miles and grips decent unless knee dragging, both aregistered budget priced (Avon is best overall).

Get some Hagon, Progressive, or YSS shocks. Do not go with $100 Chinese emgo mdi no name etc. The ride will suck.get the shocks 10mm or 15mm longer than stock if you want a very response sporty feeling ride. Stock makes it steer too similar to a lazy Harley highway straight line cruiser.

The 650 head/pistons/cylinders/carbs swap is awesome. Highly recommended. Just with an aftermarket exhaust with performance baffle and k&n pods with a 550 dynojet kit, the bike will be way more nimble quick and sporty than the sportster, maybe even faster from about 12mph to about 85mph. The Sporty will pull like a train though and has more torque of the line and the highway higher speeds.

4-1 Exhaust, k&n, dynojet, & 650 top end and the 673c. GS550 may be faster in a drag race than the sportster, & far faster on twisty roads set up as I described. You will love it if you love spirited riding.
If you love a heavy bike that goes well in a straight line and you don't take curves fast or curvey roads often, & you want a bike that feels like you're driving around an antique tractor engine from the 1920's or 1950's, that feels like sitting on a lazy boy recliner...maybe the Harley is for you.

Upgrade the regulator rectifier with a used $45 ebay unit - search "Polaris 4012941" on ebay. Great insurance.

 

[Chuck78]

When my GS750 was mostly stock (MAC 4-1 with performance baffle), my buddy with an xl1200c sportster would get me off the line for about 15', but then I was looooonnngggg gone with him in the dust. The GS's just require winding them out to at least 5500rpm to get good power. That's how they are designed. 3500-5500 is good cruising rpm. 5500-9500 is Harley smokin' RPM shift points on a GS. They LOVE to rev out high like that.

I have ridden that 1200 sportster enough to know that I love my GS750 A WHOLE HELLUVALOT MORE...
Also, the GS750 2V has 72hp stock. The 673cc GS650 has 73hp stock! More advanced head design. The 550 and 750 2V are a hemi piston/chamber. The 650 is a closed chamber modern design. More efficient.
Unless your sporty is newer and has fuel injection, a 673c gs550 with a fresh valve job and new rings on good spec used and honed cylinders will likely make more horsepower than the sportster. The sportster will still have more torque tho but the GS will be faster when ran through its prime RPM range


Just get rid of that godawful dorkpillion cushion set you have there and you'll have a fine piece of Japanese machinery once it's gone through!

Good luck, email me if you need any advice especially on brake and suspension upgrades or 673cc top end swaps.

 

[ddaniels]

You say it is a 550E, but looks more like a 550L with those bars and that seat. My first bike was a 1980 GS550L and it was very quick and nimble and a blast to ride.

 

[Chuck78]

It is an E, is has straight leg forks and other E trim. It just had a king/queen old man cruiser seat added, as well as the tall cruiser bars. The E is more sporty than an L, but I can't imagine it feeling that way with those bars!!! Superbike (~2" rise and mild sweep back) or Daytona bars (~3/3.5" rise and more sweepback, but still not hideously tall) are what is more appropriate.