No torque from GS550?

[OzJavelin]

I realise that it's no powerhouse, but I'm pretty disappointed with the torque from my '79 GS550E. In 6th gear at 100km/h twisting the throttle to pass cars is a very slow process. Dropping back gears makes it a bit faster, but a lot more noise and fuss. Repeat the same process with my Kawasaki ZR550 (Zephyr) in 6th and off it goes .. and goes .. and goes.

The GS550 is a good, mechanically original bike, but with aftermarket mufflers. Might these be hurting it? Anything I can do to improve punch at around 100km/h with a stock engine or am I just asking the 550 to play outside it's comfort zone?

[hampshirehog]

Compare the book specs. ZR550 makes 50bhp @ 10k rpm, GS550 makes 48bhp at 9k rpm (slight variation depending on model / year). Torque figures are pretty much identical: The ZR makes 30 lb ft and the GS 31 lb ft. But, the ZR makes max torque at 6k rpm whereas the GS spins it out at 7.5k rpm.

Yes, the GS loves those revs.

And it sounds as if your GS isn't running too well. Is it in good fettle?

[tkent02]

Your mufflers could be causing the lack of power, but so could a lot of other things.
Maybe they didn't jet it right when they put the pipe on, maybe the sprocket ratios are all dorked up, maybe there are other problems. Start working your way down Cliff's list, you will get it sorted out soon enough.

[Suzuki_Don]

I realise that it's no powerhouse, but I'm pretty disappointed with the torque from my '79 GS550E. In 6th gear at 100km/h twisting the throttle to pass cars is a very slow process. Dropping back gears makes it a bit faster, but a lot more noise and fuss. Repeat the same process with my Kawasaki ZR550 (Zephyr) in 6th and off it goes .. and goes .. and goes.

The GS550 is a good, mechanically original bike, but with aftermarket mufflers. Might these be hurting it? Anything I can do to improve punch at around 100km/h with a stock engine or am I just asking the 550 to play outside it's comfort zone?

Hi OZZIE, as the others have said there is definitely something amiss. A 550 has more go than that. As you know I have a 550 and can relate any info that you want. Sprocket sizes, jetting, etc. Are the brakes binding, pistons stuck, have you done a compression test - it might have one lazy cylinder. Many possibilities.

Run through Cliff's list, especially valve clearances, I have some shims if you need them (on a swap basis). What are points and condensors like, timing, etc. Are cams timed correctly (not a tooth off are they).

As I said earlier, many possibilities.

[uk gs nut]

My sons gs550 pulls like a train!. When i owned it i fitted aftermarket silencers{decibel copys}, it was a bit flat so i fitted bigger main jets in carbs small steps at a time. I ended up with 95 jets left over from my gs1000, and it also has +1 tooth on front sprocket.

[OzJavelin]

Yeah .. I'm hoping something is wrong and i can wring a bit more out of it eventually. It's a comfortable ride at the moment, but passing cars is a lot more effort than with any of my other bikes (ZR550, GPZ750R1, GS750).

It's in mechanically good condition, but I suspect the aftermarket mufflers aren't helping.

When I get time I'll have to just go back over the whole thing.