550 Top Speed problems

[Guest]

I've recently noticed that my bike tops out at ~75mph. I have only been riding for a few months so it took me a while to realize something is up. When I'm in 5th or 6th gear my revs are around 5.5-6k and wont go any higher. I can get to higher revs at lower speeds. At 75 I still have about 1/4 turn of the throttle left. When I give it more throttle nothing different happens. If this were a main jet issue I think I would expect it to stumble? I checked my throttle and it is opening the carbs all the way at full throttle.

more info on bike:
1980 gs550e
4-1 with straight though muffler
K&N pods
valve shims adjusted
I went up 3 main jet sizes and 1 pilot size.

[blowerbike]

do you have a st.3 jet kit installed?

ok i see that you don't.
your in NY and its cold i'm sure.
bump 3 more main sizes and check it out.
when you get the extra $$$ buy a st.3 jet kit and follow the instructions.

[Toasty]

Have you stripped and dipped the carbs? You're running lean but may also have a fuel starvation problem, if you have an inline filter on take it off.

And 3 sizes up on the mains isn't nearly enough with pods and a 4into1. I had to go up 2 sizes on the mains with my 550 to fix the lean condition caused by the 4-1, and I was running the stock airbox and filter.

[5150/gs]

I had a 550l,did the same thing.Sold it long before the internet really took off,wish i kept it,i would have dipped the carbs and adjusted the valves and brought her back.only had 16k on it,my brother let it rot.Things i did not know then.
Maintenance maintenance maintenece,all i can say

[tkent02]

Probably you need different main jets, but:

Have you tried winding it out?
Fourth gear until it tops out, fifth to the red line, then wide open in sixth.

550s need high RPM to make much power, especially if someone changed to taller sprockets.
Quite often sixth won't go as fast as fifth, just don't have the power to pull 6th.


On a 550 the power starts to increase at about 7,000 RPM, anything less it won't have much.

When I had tall sprockets on my 550, it would only go about 75 - 80 if you just open the throttle in 6th.

If I ran through the gears redlining each it would go about 110 - 115 mph in 5th.
Sometimes shifting to sixth it would go faster, but usually it would drop back a little.

Just didn't have enough to pull the taller gears.

[wegs426]

Thanks for all the help.

There's not many riding days left up here so I'm just going to take my fuel filter off and see what that does.

Carbs have been dipped. This winter I'll get some bigger mains in there and see how fast it can go.

..or maybe I'll find a 650 top end.

[blowerbike]

jet kit jet kit jet kit.........
good luck!

[Crankthat]

Not trying to be funny. Fix it up without spending much, shine it up, sell it a great running base for a cafe winter project. Buy a bigger/faster bike before the spring prices come up

[tkent02]

Not trying to be funny. Fix it up without spending much, shine it up, sell it a great running base for a cafe winter project. Buy a heavier/poorer handling gas hog bike before the spring prices come up

fixed it for you.

[Crankthat]

fixed it for you.

:d:d:d:d:d:d

[tkent02]

:d :d ? ? ?

[Crankthat]

:d :d ? ? ?

Every now and then I start to lose wireless connection and for some reason my Big Green Cheesy Smile come out different.

[tkent02]

This one?

[Crankthat]

That's the one!

[mrbill5491]

Straight through muffler? As in no baffle? Think I would find a baffle for it and get some restriction back into the exhaust. I wouldn't think a straight through exhaust would be all that good on the street...especially the unwanted attention it would garner.