• Required reading for all forum users!!!

    Welcome!
    Register to access the full functionality of the GSResources forum. Until you register and activate your account you will not have full forum access, nor will you be able to post or reply to messages.

    A note to new registrants...
    All new forum registrations must be activated via email before you have full access to the forum.

    A Special Note about Email accounts!
    DO NOT SIGN UP USING hotmail, outlook, gmx, sbcglobal, att, bellsouth or email.com. They delete our forum signup emails.

    A note to old forum members...
    I receive numerous requests from people who can no longer log in because their accounts were deleted. As mentioned in the forum FAQ, user accounts are deleted if you haven't logged in for the past 6 months. If you can't log in, then create a new forum account. If you don't get an error message, then check your email account for an activation message. If you get a message stating that the email address is already in use, then your account still exists so follow the instructions in the forum FAQ for resetting your password.

    Have you forgotten your password or have a new email address? Then read the forum FAQ for details on how to reset it.

    Any email requests for "can't log in anymore" problems or "lost my password" problems will be deleted. Read the forum FAQ and follow the instructions there - that's what we have one for...

  • Returning Visitors

    If you are a returning visitor who never received your confirmation email, then odds are your email provider is blockinig emails from our server. The only thing that can be done to get around this is you will have to try creating another forum account using an email address from another domain.

    If you are a returning visitor to the forum and can't log in using your old forum name and password but used to be able to then chances are your account is deleted. Purges of the databases are done regularly. You will have to create a new forum account and you should be all set.

'81 GS550T idle and high rpm issue

  • Thread starter Thread starter heater63
  • Start date Start date
H

heater63

Guest
I just finished rebuilding my carbs and and I'm having a couple issues. I'm having trouble holding a good idle. I need to keep the engine at like 2000-2500 rpm to keep it from dying. If I hold it at 2500 rpm and release the throttle for a second and then try to rev it, it won't recover, and will usually die. The other issue is that the engine tops out at about 6000 rpms. Thats with the throttle fully open ..... it won't exceed 6000 rpms.

I believe I adjusted my pilot screws correctly, but could this be the source of my problem? I tried going through the top 10 newbie mistakes to eliminate any obvious causes.

Any suggestions? Thanks for your help.
 
Yes. The stock airbox is in place. I also installed a new foam filter.
 
The choke rod appears to be moving properly and properly closing. I believe all cylinders are firing. However I just replaced both of my coils with Dyna DC1-1 coils. (cylinders 2 and 3 weren't firing so rather than replace the one bad coil I replaced both). The outputs on the Dyna coils did not specify which output went to which cylinder. So I didn't think it mattered. Maybe that was a bad assumption. So the left coil is still wired to Cylinders 1 & 4. And the right coil is still wired to Cylinders 2 & 3. But as far as which output on the individual cylinders goes to Cyl 1 and which goes to Cly 4, I unsure. That being said the engine sounds like its firing correctly. But I could be wrong.
 
Yeah. All the headers are hot. So I assume they are all firing. Could the firing sequence be wrong because of how I wired the coils?
 
Your coil connections are fine. Both wires on each coil fire every time that coil fires. That is, 1 & 4 both fire, then 2 & 3 fire, then 1 & 4, etc. I think you get the idea. So you are good at that point.
 
6000 isn't near enough- you may need an assistant for this check- make sure your slides are opening all the way when you open full throttle. An inspection mirror and light might help too- depends on your help. I'm in a similar situation with my newly rebuilt engine/carbs with idle creeping and difficulty synching.
I suspect vacum leak at the airbox since the boots are really stiff and clamps are not healthy looking- these temps have me on hold-
I remember reading someone with a foam filter over oiling it and what you described too- he washed it out and lightly oiled and fixed it. Try that first if it applies.
 
Last edited:
Did you take the carbs fully apart, soak them in dip, and reassemble with fresh O-rings? Replace the intake boot O-rings? Valves adjusted? Set the pilot mixture screws at 3 turns open?



Badooka said:
6000 isn't near enough- you may need an assistant for this check- make sure your slides are opening all the way when you open full throttle. An inspection mirror and light might help too- depends on your help. I'm in a similar situation with my newly rebuilt engine/carbs with idle creeping and difficulty synching.
I suspect vacum leak at the airbox since the boots are really stiff and clamps are not healthy looking- these temps have me on hold-
Click to expand...


There is no need to go though all that. Just rebuild your carbs properly and check the parts while everything is apart.
 
Last edited:
I did take the carbs fully apart. I soaked all metal parts in carb dip. I replaced all the gaskets and o rings. My pilot screws are 2 1/2 turns out. I did not adjust the valves though. I didn't replace the O rings on the intake boots. The thought about removing the boots but I thought I was going to strip the Phillips screws that secured them. I decided not to try and remove them until I knew I had to. They boots look to be in decent shape.
 
Hi heater63, follow all the tutotial & guideline that had been given. Previous i just let my mech to do it (biggest mistake but no option) but now i DIY my self with the guideline & tutorial from GS resources members. Now my GS run great and healthy. There is no easy way to ensure the GS run well... you can read my hard journey with my GS in the GS story section.

Happy DIY... :D
 
Last edited:
Yes there is, having clean slides won't make a difference in adjusting them so they are fully open and the slide is even with the throat in WOT- this is a small item that can be missed and you'll never know if the bike is operating at top end-
 
So I think I've determined that this is an ignition issue. As I mentioned before, last week I noticed that the plugs on cylinders 2 and 3 were not firing. So I ordered new Dyna DC1-1 coils and replaced both of the original coils. I test them after installing and verified that all 4 plugs got a nice big blue spark. Today I tried starting up the bike again and noticed that the headers on cylinders 1 and 4 were very hot, but 2 and 3 were just warm to the touch. So I pulled the plugs on 2 and 3 and saw that they were not firing (well sometime I would get a single spark if I tried for a few seconds).
Does this sound like a bad ignitor? Do they fail intermittently? Seems strange that the coils seemed to work just fine 2 days ago ...but now I am seeing the original problem.

Any ideas?
 
I'd check voltage at the coils. Should be battery voltage or slightly less.
 
Hey Ed, I checked the voltages at the coils. They are both getting approx 8.8V. It sounds like it should be closer to 12V. Is that a symptom of a bad ignitor? Also, I followed the ignitor test outlined on BassCliff's site ... (using a multimeter to bypass the signal generator and fire your plugs.) I was unsuccessful. I did however verify that the signal generator had a resistance that was in the correct range.
 
Resistance in the wiring harness knocks down the coil voltage, which effects spark. Your coils should be getting at least 11 volts, or more. You can try cleaning up the harness connectors or look for the Coil Relay Mod on Cliff's site. Once you get your head around what needs to be done it's really easy.

You can grab power from the accessory screw on the fuse block.

Good luck

Edit: http://members.dslextreme.com/users/bikecliff/images/coil_relay_mod.html
 
Last edited:
You must log in or register to reply here.
Back
Top