Help. What do I try next? 1980 GS550L

[Guest]

Hi guys, I'm new to all of this and don't know where to turn after reading through other forums.

I have:
Adjusted valves
Cleaned (dipped) carbs
Replaced all carb o rings
Checked float height (22.4 mm)
Replaced intake o rings
Replaced gaskets for everything I touched

I'm unsure whether or not (or how to check if) jets are stock or a PO has changed anything. However, I haven't found anything on the bike that isn't stock.

My problem is getting to bike to stay running. If I get it to start it will only idle at 2000+ RMP. Anything lower and it wants to shut off. Also, if I twist the throttle too fast it will shut off. After shutting off it doesn't want to start back up.

Sorry if this has already been answered elsewhere, and thanks for any advice in advance!

[tkent02]

What technique did you use to adjust your mixture screws? Did you synchronize the carburetors? How?

And...

If it's fully warmed up does it work any better?

[eil]

Hello and welcome! Based on your list of maintenance items, I assume you've been lurking here for a while.

To find out if the carbs have been jetted, take them off and compare the numbers on the jets to the specs in the service manual.

Whereabouts are you? Ypsi-Arbor here. If you're close enough, I might be able to lend a hand, although my free time is vanishingly short in the summer.

[tom203]

Make sure that all 4 spark plugs are firing otherwise it won't be happy ! See steps in this link...

http://members.dslextreme.com/users/storagecliff/images/electrical_odd-n-ends.html#A17

[Chatfield102]

Hi guys. Yes, I have spent a bit of time on these forums, but I have learned a bit. Thanks to all for sharing.

I set all of my mixture screws 2.5 turns back. I saw several ways to fine tune them but wasn’t sure which was best. I was going to try to figure that out next (unless someone has any suggestions.)

I have not synchronized them yet. I quite literally just got everything back together. I have a friend with a gauge helping me with that tomorrow.

It does seem to work better with it warmed up. Also, (I’m ashamed to admit) it works better with gas in the tank… I guess after waiting on parts and finally getting everything back together I overlooked checking the fuel level. Now it is comfortably idling at about 1000 RPM.

I will take a look at the spark plug page as soon as I have a moment later. I don’t have much free time in the summer either.

I don’t know enough to know whether the problem was just low gas or if I need more help? I am close to the Ypsi-Arbor area though. I’m just south on 23, outside of Milan. I really appreciate the offer.

I also noticed when riding, anything over 4000RPM is what seems to be a VERY slow climb to me regardless of how much I twist the throttle. I’m not sure that this is normal.

Sorry if I should have synchronized the carbs before asking any questions...

Thanks everyone

Kyle

[Big T]

Your problems point to a lean condition

Air box sealed?

[tkent02]

I also noticed when riding, anything over 4000RPM is what seems to be a VERY slow climb to me regardless of how much I twist the throttle. I’m not sure that this is normal.

Not normal at all, the 550s are about dead below 3,500RPM, can barely pull themselves along level ground. They gain a little power at 5,000, at 6,000 they start to pull pretty hard and after about 7,500 up to well past the red line they take off like a shot, easily doubling the power they make at 5,000. It's almost like a two stroke.

If yours doesn't like to go above four it has very serious problems. I don't think I ever ride mine below 4,000 except to idle while stopped.

[Chatfield102]

Hmmm..any idea what I try next? Or what that means?

[60ratrod]

sounds like a weak ignition system. if you have the stock coils with the plug caps, try trimming back a bit of the wire and reinstalling the caps. also check the voltage at the coils. it should be close to what the battery is reading. low voltage will result in weak/hard starting, and lack of power through the rpm range. if the voltage is low, then you may be in for a coil relay mod. voltage at the coil on a charged battery should be within .5vdc at the coil. anything less means you are losing voltage due to an aging electrical system, but can be solved by cleaning the electrical contacts, but not always the case.

[tkent02]

This is puzzling, usually full throttle is easy to get right, there are not really any ports or passages involved which are likely to clog. It's full blast on the air and you have the whole big main jet bringing in fuel, which is easy to clean and rarely clogs anyway. The mid and low power part of it that is usually the problem, as well as starting and idling, as there are much smaller passages involved...

It's a 1980 so you have electronic ignition, which usually either works or it does not. It's not likely to cause poor running like the old contact points ignitions could if they weren't maintained. Unless of course the spark plugs or wires are bad. You have big bright blue sparks on all of the plugs?

I have seen symptoms as you describe with a clogged exhaust, either from animals living inside leaving nests behind, something inside the pipe coming loose and blocking the muffler, or in one case a big wad of steel wool someone put in the collector of a 4-1 pipe to quiet it down, I guess. That one was a GS1000, it would only get up to 50 mph down a fairly good grade, on level ground it would only do about 40. It ran fine at low RPM. Pulled the steel wool out and it was good as new.
Don't know if this is your problem but it's worth a look.

Could also be a cam timing issue, have you checked that? I have found a lot of old bikes with cam timing errors, people just can't seem to leave this stuff alone. Another possibility is ignition timing but no one usually messes with that so it's probably OK. More likely spark advance, it is mechanical and sometimes they get stuck, is yours working?

[Chatfield102]

Sync is now done! Airbox is new. I am getting good sparks. Will check out the can timing as soon as I have a moment. So short on time lately and an oil leak just popped up :/ I may have been unclear and maybe just expecting more pull from twisting the throttle in higher gears. I am brand new to motorcycles. It will get up in RPMs (up to red line) when accelerating...