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1980 GS 550 no power after 60mph

  • Thread starter Thread starter bodcherokee
  • Start date Start date
I still say make sure the advance mechanism is actually advancing...
 
tkent02 said:
The 550s have almost no low end grunt. Power should be very weak below 3,000 rpm...
getting fairly strong at 4,000 - 6,000 gradually increasing through 7,000.
and take off like a rocket at about 8,000 - 10,000. In the first couple gears at 8,000 rpm, it will take a strong grip to hang on to the bars. These are very short stroke engines, it does not hurt them at all to go to the high rpms and stay there all day. Ridden well and kept in the power band, it will smoke all but the fastest of cars up to 100 mph or so.

Usually just opening the throttle in sixth from a low speed it will top out at about 75 or so mph, but if you wind out fourth, take fifth to the red line and hit sixth it will accelerate right on up to red line in sixth gear.

These bikes are great if you like to wind things out. If you would rather open the throttle and chug on out, not so much.

If you have never ridden at all you really need some local help, post a location, there are people on this forum in your area who would be happy to help out.

Unless you have near zero compression, the problems you are having is not caused by anything internal in the engine.
Click to expand...

It wont even rev up past 4500 rpms in 4th 5th and 6th. I wish it would rev to 10000. It will sitting in neutral but not on the road. as far as being sure about the exhaust not being clogged, i mean the tail pipe pushes it out at a good pressure on both pipes. i guess i could pop the pipes off but i dont wanna mess with the gasket yet. Also figured i'd throw in a picture of her. I'm located in springfield, ma by the way.
timsbike2.jpg

timsbike1.jpg
 
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I honestly think that you need to re do your carb cleaning. you need to completely tear them apart, making sure the jets and emulsion tubes etc are spotless. unless you do this you are barking up the wrong tree. Theres a link how to do it properly on Bass Cliff's site and other places.
 
The clogged exhaust thing, I have had this on two GSes now. One of them, a 1979 GS1000E, would only get up to 50 mph on a long down hill. It started fine, idled nice, ran OK at low rpm but got worse at it wound up, seriously 50 mph needed a hill. I noticed it was running very rich, and also very quiet, with a Vance and Hines 4-1 pipe and stock jets this didn't make sense. I poked a coat hanger down the pipe and started pulling out steel wool, the PO had been stuffing steel wool down into the pipe to make it quiet. Pulled out about six big handfuls from down in the collector. After that it was fast.
The other had mouse nesting materials in the pipe, it was slow as a dog too but not as bad as that one.
Just something for you to check.
You should definitely check the spark advance, that will kill high RPM as well.
As far as carb cleaning, the wide open throttle circuits in the carbs are the least likely to be clogged, they are larger and they don't have to be as perfect as the low speed stuff to run somewhat correctly. IF it idles nice with good low throttle and mid throttle response it's not so likely to be the carburetors causing the problems. Possible, but not so likely.
Unless your main jets are not the right size.
 
bodcherokee said:
i honest have no idea how to do that lol
Click to expand...

Take off the ignition/timing cover (the round one with the Suzuki emblem on the right side held on by 3 screws).

Under there, you'll see a round plate with two boxes mounted on it 180 degrees apart, and these are the ignition pickups. In the centre is a rotor.

You should be able to grab the rotor with your fingers and turn it maybe 90 degrees clockwise fairly easily *without* the crankshaft turning.

When you let it go it should spring back to the original position by itself.

This photo is how it looks on my 450. I think yours will look a bit different but the components are essentially the same. Just ignore the Dynatek I'm holding in my hand and look at the left side of the photo.

IMG_3111.jpg


Don't turn it by the nut on top of the rotor, turn it by the rotor lobes.
 
bodcherokee said:
Thanks for all the info everyone. I have heard from a few people to pop the side cover and advance the timing. It has the stock air box on it and i'm thinking of getting a set of cones. It doesn't rev past 4500rpms just like you said too. I'm also looking on advice on rebuilding a my 550 engine. I have the one off my donor and i have rebuilt car engines but never a motorcycle one. Anyone know where i can get parts and gasket sets? Thanks again, love these kinds of forums, i build jeeps and i use those forums all the time. Better than any haynes or chilton book you can buy and this is free.
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The timing is preset, so if the advancer unit works - don't ever get advice from them again

You do not need "more" air, again this is backwards thinking. You need the correct air/fuel mixture at the higher RPMs. If it's not running rich, you don't need more air

What do your spark plugs look like?

What are your compression readings?

Why would you rebuild a perfectly good engine?
 
Big T said:
The timing is preset, so if the advancer unit works - don't ever get advice from them again

You do not need "more" air, again this is backwards thinking. You need the correct air/fuel mixture at the higher RPMs. If it's not running rich, you don't need more air

What do your spark plugs look like?

What are your compression readings?

Why would you rebuild a perfectly good engine?
Click to expand...

Spark plugs are the ones it came with out of the barn and they are a little dark. Havent done any compression tests. Im thinking of rebuilding the engine because i bought a donor bike and i have a spare everything and i live in the northeast so i have all winter to work on the bike. In the end im trying to get this bike to at least be able to ride with the new gsxr that my buddy is buying in the spring. I know he'll smoke me no matter what i do, i'd just like to at least hit the highways.
 
bodcherokee said:
Spark plugs are the ones it came with out of the barn and they are a little dark. Havent done any compression tests. Im thinking of rebuilding the engine because i bought a donor bike and i have a spare everything and i live in the northeast so i have all winter to work on the bike. In the end im trying to get this bike to at least be able to ride with the new gsxr that my buddy is buying in the spring. I know he'll smoke me no matter what i do, i'd just like to at least hit the highways.
Click to expand...

Well, you're going about the "reviving the barn find" backwards

You need to do all the deferred maintenance first, then fix whatever else is wrong. See the "ten Common things" and go from there. Anything you need (other than tools) is on BassCliffs site

There are any number of probable causes for the problem you posted about

Clogged gas tank vent
Clogged petcock
Clogged carbs
Valves need adjusting
Torn carb diaphragm
Carbs out of sync

It is common to not get the carbs clean enough. See the tutorial on this
 
ok so over the weekend i popped the round cover and the timing turns about 90 degrees then snaps back. also spins just fine when running. I'm thinking more and more that i'm going to have to have someone do my carb work because now after sitting for a month it runs worse now. Sitting in neutral it will idle fine but when i try to rev it up it goes to like 7500 then bogs back down to idle with the throttle open. If anyone knows of any shops that are good in western mass, please let me know.
 
You should do all of your work and you'll have it done far cheaper than any shop can do. See Basscliff's site for the tutorials and have at it.
 
Well i guess it will be cheaper to do it myself, i'm just gettin a little frustrated with ripping this thing apart to get the carbs out and putting it all back together again and again and again. Those carbs are mad hard to get out too. how do u adjust the valves because mine are pretty loud.
 
Valve adjustment procedures are also available on Basscliff's site while you will want to email Steve (name and username on here) for his spreadsheet.
 
Holy crap, thank god i started this thread. That website is the greatest thing i've ever seen. Step by step and a free service manual. Can't find anything like that for my jeeps. cant wait to get started on re-cleaning my carbs. Just looked over his step by step and already found a few things i missed. Thanks guys!!
 
Sometimes if you loosen up the rear fender you can get a little more clearance for the carb removal (if the air filter box is hitting it moving back).

Carb cleaning:

http://www.mtsac.edu/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf

I've heard it said "a slappy valve is a happy valve". The valve clearances usually wear tight over time and that's where the problems start - a slight sewing-machine type noise from the valves is a good sign. The spec on the valves is 0.03-0.08mm, though it's OK to run them a little looser (I've heard of 0.12 without any apparent ill effects, and run 0.10 myself on a few valves).

Get yourself some metric feelers and a new valve cover gasket. The most frustrating part of valve adjustment is waiting for the new shims to come in...

http://members.dslextreme.com/users/bikecliff/images/gs850valve_adjust.pdf

The zip-tie supplement if you want to avoid buying a shim tool:

http://members.dslextreme.com/users/bikecliff/images/valve_tool_zip_tie.pdf

As Mr. Cowboy pointed out, Mr. Steve distributes an Excel spreadsheet which you can use to track and calculate your gaps and needed shims.

bodcherokee said:
Well i guess it will be cheaper to do it myself, i'm just gettin a little frustrated with ripping this thing apart to get the carbs out and putting it all back together again and again and again. Those carbs are mad hard to get out too. how do u adjust the valves because mine are pretty loud.
Click to expand...
 
ok so after spending like 2 hours looking through basscliff's site, i've come to the conclusion that i missed a few things on the carb cleaning so i'm goin to redo that, i never cleaned the petcock so i will do that and make sure the tank breather is clear, then i'll do an oil change and a new set of plugs. hopefully that will about do it for now. I would like to adjust the valves but thats a little more involved right now. i am seeping oil out of the valve cover so i may end up doing it anyway. Can't say thank enough guys for all the info, i'll let you know how it comes out.
 
bodcherokee said:
ok so after spending like 2 hours looking through basscliff's site, i've come to the conclusion that i missed a few things on the carb cleaning so i'm goin to redo that, i never cleaned the petcock so i will do that and make sure the tank breather is clear, then i'll do an oil change and a new set of plugs. hopefully that will about do it for now. I would like to adjust the valves but thats a little more involved right now. i am seeping oil out of the valve cover so i may end up doing it anyway. Can't say thank enough guys for all the info, i'll let you know how it comes out.
Click to expand...

Don't forget to get a new set of O rings from cycleorings.com if you didn't already do that. Actually, get another set anyway, they're cheap enough...
 
pete said:
Don't forget to get a new set of O rings from cycleorings.com if you didn't already do that. Actually, get another set anyway, they're cheap enough...
Click to expand...

thanks thats great, $15 shipped! cant beat it. Anyone have any recommendations on the chemical i should use to soak the carbs and jets?
 
What the articles say - Berryman's found at your local auto parts shop; even Walmart started carrying the gallon can out here.
 
Any update on this issue? I am having the same problem and scratching my head.
 
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