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Low power and torque at low rpm on GS550 E -82

  • Thread starter Thread starter Anonymous
  • Start date Start date
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Anonymous

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On your bike, the cams are not degreed to a specific setting, they are degreed within a range. On the early GS's the range can be about 100-115+ degrees. This is the main reason two identical bikes will perform differently right out the door. If you have the cams degreed around 110, this will result in more top end/horsepower, but the low/midrange torque will suffer. If you degree the cams around 100-102 you will have more low end torque. I had both my intake and exhaust cams timed at 106 degrees for what I consider the perfect compromise between top end/horsepower and lower/midrange torque.
Higher degreed cams (112-115+) will result in slower warm ups, a hotter running engine, the carburetion is difficult to set correctly and a narrower powerband.
With your cams timed at 104-106 degrees, you'll have a broader powerband, better throttle response and the best compromise between peak and low rpm power, gas mileage will be at it's best too.
Click to expand...

This sounds so nice so I have to follow it up. The quote is from a question on cam adjustment for a 750 and i wonder if I can do the same on my GS550 E fron 1982. Also since my english doesn?t follow so well so I would like to have a better explanation. How kan you adjust cams when they are driven by a cogwheel? One rack +/- would be a to big adjustment, wouldnt it?

I have a very low torque and no power at al at low rpm?s. I also think my 550 is very thirsty.

90 8)
 
In order to change the cam timing you have to have slotted cam sprockets. I'm not sure what's out there for the 550, but any good machine shop should be able to redo a stock set.
 
what is 'low' rpm to you?

i remind you that its a small motor...and an inline 4, so its going to lack torque down low. i would say my 550, with pod air filters and 4-1 exhaust, has no power below 4000 RPM. genereally i shift to a higher gear if i drop below 4000 RPM. sure the bike can pull, but slowly, from lower...but you can't expect huge power from a little engine at low RPM.

~Adam
 
I would check the ignition timing and synch the carbs.
I agree with Adam: a GS550 doesn't have the "punch" of power that the bigger GS's have.
 
mmm...jojo i'm sure i could easily smoke a 650 and hang with a 750 in my slightly modified form. ;)

i was just saying no inline motor has torque down low. they make power in the high revving ends.

~Adam
 
Like Gary said, you can buy slotted cams or modify the existing holes yourself or by a mechanic. Cam timing of 106 degrees is perfect for a 550.
As others mentioned, a 550 does'nt make a lot of power at lower rpm's. The cams timed properly will certainly do their part, but there are many other reasons your bike may be lacking power.
Poor ignition performance, worn parts in the carbs, dirty carbs, poorly synch'd carbs, improper jetting, dirty/restricted intake, intake leaks, valves out of adjustment, poor compression, etc, or any combination of these.
Your bike may be running like a 550 should. We all have a different opinion about how much power "feels right".
But if you think you have a problem and you don't mind spending the time or money to fix it, then start checking things out. A good starting point is a compression check. Then an ignition check...
 
How much would some thing like getting my cams slotted cost. I asume you would take them off yourself and take them to a shop to have done. Getting cams sloted, is that a common request for a machine shop to do? If i was to get them sloted and degreed right, would it make a big diffrence in my bike? I have already have done a stage 3 jet kit, pods , 4 into 1, accell coils.
 
first timer said:
How much would some thing like getting my cams slotted cost. I asume you would take them off yourself and take them to a shop to have done. Getting cams sloted, is that a common request for a machine shop to do? If i was to get them sloted and degreed right, would it make a big diffrence in my bike? I have already have done a stage 3 jet kit, pods , 4 into 1, accell coils.
Click to expand...

Some people just slot the holes with a power hand tool or even a file. I bought mine so I cannot say how hard it is to slot them or how much a shop would charge you. As part of a complete engine rebuild,Vance&Hines charged me 2 hrs @ $60/hr to set the cam timing, I believe the sprockets cost $50.
Degreeing your cams to 106 is good for a stock bike as well as a bike with your mod's. But remember, the cam timing is only 1 part of the overall engine. The engine is only as good as the sum of it's parts. Also, it is possible that your cam timing may be at 106 now and you don't know it. But odds are it probably is'nt. You need to have it checked first by a mechanic YOU TRUST. Some do not really know how to do this right. Or, learn to do it yourself.
 
thank?s

thank?s

Thanks for the replies. I?ve compared my 550 with a friends and therefor i thougt i have low torque and a lack of horse power. My engine starts at ca 7000 and I think it could wake up a little earlier. I?ll start vith the carbs and the air intake.

When driving hard and then stop the engine will not idle. Its no problem to start again and it will idle very nice at 1000 rpm directly. Its no big problem but perhaps it can tell someone if there is a problem with the carbs.
 
pilot jets might be clogged...or the passages in and around them.

clean the air filter too.
 
The mods you already have on the bike will kill off some of the bottom end, and from I remember of my 550, there wasn't a whole lot to start with.
 
Nitti, I have seen a lot of different bikes with that brief idling problem after hard riding. My bike does it a little. It does'nt actually stall but it will briefly want to idle at about 800 rpm instead of 1000rpm. My friend just bought a 1 year old Triumph Speed Triple and it has done it a few times. Otherwise his bike runs perfect and is barely broken in. He has fuel injection, so it's not just a "carb" thing. I have some opinions on what causes this but I take too long to type out my thoughts. I have tried minor adjustments to my pilot and air screws and it does'nt seem to make a difference. It is interesting that the engine turning off seems to help and it only happens on a hot motor. Maybe some kind of temporary vacuum? Here I go, I better stop.
Like you said, it's easy to live with, especially if you are expecting it. Just give a slight turn on the throttle if you think it's going to stall, a few moments later, the rpm's pick back up. If you ever find out for a fact what does this, let us know too.
 
my bike would stall out like yours nitty, especially when it gets hot. Come to find out I think I was runin a little rich so I dropped my needles down one notch and it seems have smoothed thing out and my bike doesn't stall nearly as much now. It only seems to stall under HARD stopping when the bike is hot.

KEITH, how do you know so much good info on the 550, I don't doubt your knowledge but where did you get the info for the cams 106 degrees. Is there a secret stash of 550 tricks I don't know about? :P winters comin and I will get bored.

Ryan
 
Buy 'em

Buy 'em

If you can get adjustable cam sprockets for $50, don't even bother with trying to have a machine shop make them, or slot them yourself.

Sounds like you definitely have issues other than cam timing on that 550. My little 550 had plenty enough bottom end for its size.
 
my bike has plenty of bottom end, i just thirst for more power myself. nitty i think you just need a good tune up on your bike.

anyone have any ideas or rember companys that sold adjustable cam sprockets or other performance mods for the 550 back in the eighty's, i was only 6 when my bike was on the market so i missed my chance to get the good parts.

ryan
 
first timer, I first read about cam timing in the Dec.'84 issue of Motorcyclist magazine. They built a '79 GS1000 project bike and I wanted to build mine just like it. One of the mod's they made was to set the cams timing to 106 degrees. I have always respected their advice and they gave several reasons why this should be done. I have heard many others(mechanics/other owners) agree with this over the years. This is a good "mod" for stock or modified DOHC motors.
Of course, there is a chance your cams are already set at 106, but they probably are not. You would need to have it checked first. You need a degree wheel, a top dead center tool,(2 stroke timing set)basic tools and a factory shop manual. Motorcyclist used a rat-tailed file to slot the cam bolt holes. As of 3 1/2 years ago, Vance& Hines sold me the slotted sprockets. Maybe you can still find some or just file yours.
The Oct. '80 issue of Motorcyclist had a "how to" article on cam timing.
 
Keith, if 106 is supposed to be good...i'm just curious what the cam timing is set to from the factory?
 
AOD said:
Keith, if 106 is supposed to be good...i'm just curious what the cam timing is set to from the factory?
Click to expand...

The early GS's came from the factory with cam timing set anywhere between 100 to 115+ degrees. I guess manufacturers, at least back then, had a lot of difficulty holding the timing to an exact setting. Maybe assembly line time tables had something to do with it? This wide range of settings was the main reason for differences in performance between 2 identical bikes right off the floor.
It's possible your bike was timed at 106 or close, but the odd's are it is'nt.
 
Thanks for all your answers

Thanks for all your answers

I was a litle bit lazy and thougt that I wait untit winter to start fixing it. Meanwhile the temp dropped a lot and at 0-5 degrees C the bike runs perfektly well. Colder air means more oxygen. I now thing carb setting is a little rich (for normal weather). How do i fix that? Something with a needle? It?s a big step for me to dismantle the carbs (all four of them) since im used to one carb. Do I have to sync them afterwards?

And AOD, where did you get your motor spoiler. It looks great.

90
 
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