• 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.

650 vs 550 mechanical advance issues

  • Thread starter Thread starter wegs426
  • Start date Start date
W

wegs426

Guest
I have a '80 550e that I have swapped the top end of a 650g onto. It has been running great in the low and midrange, however I cannot get into the top range. Initially I though this was a jetting issue (was running dynojet stage 3) but have bumped to larger jets and the problem remains.

I have read somewhere that I should be using the 650 ignition but I am not.
I have since removed both mechanical advanced to check out the differences. The 650 has stiffer springs and advances further than the 550. They also use 2 different rotors (650 uses 1 magnet and 550 uses 2)

650 on left 550 on right
uO6OBM5.jpg


The easiest thing to do is to swap the 650 advance unit with the 550 rotor.

If this doesn't work I guess I have to swap the whole ignition system.

I will update on the results but I am skeptical that such a small difference will have a large result.
 
I made changes and am left with confusing results.

I managed to fit the 550 rotor onto the 650 advance, but I also had to use the 550 weights. This made quite a bit more tension in the springs. I can probably file the 550 rotor and get it to fit with the 650 weights.

The bike fired up and it now has a stumble at ~2k, The bike is still stumbling a lot around 6k, I think I can push through it but need to try on the highway.

I'm not sure what my next step should be. I should probably go back to the smaller stock dynojet jets, but I can't be certain that it will fix anything.
 
The advance units (and signal coil setup) likely have to be paired with correct ignitor unit.On the 650 one, that little tab swings by signal coils and triggers them. Your 550 unit is totally different- much broader, seems awfully broad-is it actually magnetic?
When you swapped the top end, do you have the correct pin count on camshafts?
 
Here's your answer:

I have since removed both mechanical advanced to check out the differences. The 650 has stiffer springs and advances further than the 550.

Switch out the springs for some stiffer ones & file the advance "arms" to allow the rotor to advance where you need it to be. If you have the right timing gun you should be able to file it little by little until you get where you need to be.

Right now with the weaker springs you have your advance coming in sooner (this may or may not be a problem, or may require you to run High test Gas in order to prevent Pinking (Knocking). You could fit heavier springs from somewhere (maybe the other advance mech?).

I suspect the higher revs issue is connected to not enough total advance. You may find that you can file slots into the mounting holes on the plate & increase the static advance to compensate but personally I would go with filing the arms as running additional static advance can bring problems at idle etc (although you might find you can overcome it by running a higher than stock idle - not what I would do personally but might work for you).

I WOULD NOT mix and match the ignition components as you have done but if I was going to mix & match them I guess you are going about it the logical way.

As another thought - Have you tested that Ignitor you are using? Is it known to be good? I had a 6k stumble problem (that couldn't be pushed through) on an 80 1000G that actually turned out to be a faulty ignitor, it ran faultlessly elsewhere.

Have you considered mounting a Dyna S or Dyna 2000 ignition as an alternative? The Dyna S allows independent movement of the pickups & of the plate so you might find it provides the range of adjustment you need. If you mounted a Dyna S the rotor is fixed & advance is electronic (with several curves to choose from & a programmable option).

Just some ideas...

:)
 
Last edited:
tom203 said:
The advance units (and signal coil setup) likely have to be paired with correct ignitor unit.On the 650 one, that little tab swings by signal coils and triggers them. Your 550 unit is totally different- much broader, seems awfully broad-is it actually magnetic?
When you swapped the top end, do you have the correct pin count on camshafts?
Click to expand...

The 550 rotor is not magnetic. When I swapped the top end I kept the 550 cams and made sure that the cam timing was set as per factory specs. The only reason I am changing out the parts is to make the 550 advance further as per 650 specs (40 deg BTDC above 3500)
 
salty_monk said:
Here's your answer:

I have since removed both mechanical advanced to check out the differences. The 650 has stiffer springs and advances further than the 550.

Switch out the springs for some stiffer ones & file the advance "arms" to allow the rotor to advance where you need it to be. If you have the right timing gun you should be able to file it little by little until you get where you need to be.

Right now with the weaker springs you have your advance coming in sooner (this may or may not be a problem, or may require you to run High test Gas in order to prevent Pinking (Knocking). You could fit heavier springs from somewhere (maybe the other advance mech?).

I suspect the higher revs issue is connected to not enough total advance. You may find that you can file slots into the mounting holes on the plate & increase the static advance to compensate but personally I would go with filing the arms as running additional static advance can bring problems at idle etc (although you might find you can overcome it by running a higher than stock idle - not what I would do personally but might work for you).

I WOULD NOT mix and match the ignition components as you have done but if I was going to mix & match them I guess you are going about it the logical way.

As another thought - Have you tested that Ignitor you are using? Is it known to be good? I had a 6k stumble problem (that couldn't be pushed through) on an 80 1000G that actually turned out to be a faulty ignitor, it ran faultlessly elsewhere.

Have you considered mounting a Dyna S or Dyna 2000 ignition as an alternative? The Dyna S allows independent movement of the pickups & of the plate so you might find it provides the range of adjustment you need. If you mounted a Dyna S the rotor is fixed & advance is electronic (with several curves to choose from & a programmable option).

Just some ideas...

:)
Click to expand...

The weaker springs that I am running, when paired with the weights from the 550 actually makes it advance later since there is more "preload" on the springs. I have observed that it definitely advances all the way by 4000 rpm (650 specs call for 40 deg above 3500 rpm). I going to play around with these parts, but I have never considered the the ignitor.

This is the same ignitor that I ran on the 550 (which had the same problem unresolved).

Also from my testing today I can barely push through it but I have to go WOT and then very slowly back off until it starts accelerating.

I'll try a few more things but a dyna s may be in my future. I would really like the 2000 but I spent all my budget on brakes :p
 
salty_monk said:
Have you considered mounting a Dyna S or Dyna 2000 ignition as an alternative? The Dyna S allows independent movement of the pickups & of the plate so you might find it provides the range of adjustment you need. If you mounted a Dyna S the rotor is fixed & advance is electronic (with several curves to choose from & a programmable option).

Just some ideas...

:)
Click to expand...

On my Dyna S the rotor advances and retards and is controlled by the strength of the springs. It is not electronically controlled as in Salty's case.

I have been through this. As you will see I have done this same conversion some time ago but used 650 camshafts for more broad torque curve.

I have a solution but am too busy at present (night work, 12hr shifts, etc) to reply here.

I will endeavour to post to you in a few days if I can find the necessary time.
 
Last edited:
Just to mention, salty dog misspoke. He meant to say that that the Dyna 2000 is an electronic advance. Whenever the springs are present, it is a mechanical advance, and he knows that.
You have a mechanical advance, same as a Dyna S, and there are a couple of issues involved in a mechanical advance:
Full advance
Rate of advance
These factors are influenced by the strength of the springs (weaker = faster rate), the mass of the weights involved (heavier = slower) and the form of the plates (stop).
AFA the 2 vs. 1 issue, IDK
So, a lighter spring will cause it to advance faster.
A heavier weight will cause it to advance slower.
The place where it stops is machined into the plate (in degrees).
 
Thanks for all the responses.

koolaid_kid said:
Just to mention, salty dog misspoke. He meant to say that that the Dyna 2000 is an electronic advance. Whenever the springs are present, it is a mechanical advance, and he knows that.
You have a mechanical advance, same as a Dyna S, and there are a couple of issues involved in a mechanical advance:
Full advance
Rate of advance
These factors are influenced by the strength of the springs (weaker = faster rate), the mass of the weights involved (heavier = slower) and the form of the plates (stop).
AFA the 2 vs. 1 issue, IDK
So, a lighter spring will cause it to advance faster.
A heavier weight will cause it to advance slower.
The place where it stops is machined into the plate (in degrees).
Click to expand...

I would actually think that the rate of advance is slowed for less weight.
Either way the weights are very close in weight the largest difference is where the springs loop to the weights, which effects the intitial tension in the springs. There is also a slight size difference in the lobes which fit into slots on the rotor (enough to where they are not interchangeable) This is why I had to pair the weights with the rotor.

My question now is the differences between the dyna s and the dyna 2000 as there seems to be some confusion on which does what.
Primarily, does the dyna s use the stock ignitor and/or springs/weights?
Will I need to upgrade coils with either system?
 
I want to update this thread as I finally have my bike running well.

I ended up installing all the 650 mechanical advance parts. Didn't fix issue.
Then I upgraded to the dyna s and kept the 650 mech. adv. thinking the ignitor was faulty. Still didn't fix the issue.
Then I went back to playing with the jetting. I wasn't having any luck with that either (tried going rich and lean).

All this time my fuel consumption has been getting worse and worse (thought it was jetting).

This week after another jet swap my bike started spewing gas out the exhaust and running on 3 cylinders. After reverting the jet swap it was still doing it. I did a quick search and determined it was my vacuum petcock. Turns out I had a hole in the diaphragm which slowly got worse and worse over the last 5 months. This was sending fuel into the vacuum port of carb #2 and flooding the cylinder. I swapped a different petcock on and took it for a ride.
It pulled hard like it never has before. It was terrifying in the best way.
Thank you for all the help.
 
Glad it's running "terrifying in the best way" and thanks for update. I wish more folks would check/replace petcock to rule it out ASAP and then looking for other problems. enjoy
 
You must log in or register to reply here.
Back
Top