• 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.

Still stumbling

  • Thread starter Thread starter slip
  • Start date Start date
S

slip

Guest
Ok, my bike is still stumbling a little in the mid range of throttle. Things done so far are:

Rebuilt VM29 carbs
Cleaned K&N Pods
Installed new coils and plug boots

One thing I did do that might be a problem is, I put the needle clip in the second position from the top. It was in the middle position. When I got it, it was running rich. But that could have been from a number of other things, not nessesarily the jetting.

But there is something else that might be causing a problem too, and that is, I only get about 12.8 VDC at the battery while revving it to about 7k rpms. I think my stator is putting out about 60 VAC at that rpm. In my mind, low primary voltage is going to equate to lower secondary voltage, and hence weaker spark! What does the collective minds of the gurus think???
 
slip said:
Ok, my bike is still stumbling a little in the mid range of throttle. Things done so far are:

Rebuilt VM29 carbs
Cleaned K&N Pods
Installed new coils and plug boots

One thing I did do that might be a problem is, I put the needle clip in the second position from the top. It was in the middle position. When I got it, it was running rich. But that could have been from a number of other things, not nessesarily the jetting.

But there is something else that might be causing a problem too, and that is, I only get about 12.8 VDC at the battery while revving it to about 7k rpms. I think my stator is putting out about 60 VAC at that rpm. In my mind, low primary voltage is going to equate to lower secondary voltage, and hence weaker spark! What does the collective minds of the gurus think???
Click to expand...
12.8 at 7K means you have charging problems to say the least. either your stator, or your RR are shot, or you have some corrosion going on in the wiring... Id suggest tending to that before you move on with the carbs.. Secondly, without doing plug chops in the necessary throttle positions, you truely have no idea where your carbs are rich or lean. The needle may have nothing to do with your problem, but the stumbling is most surely due to your moving the clip.. put it back, fix the charging issues, and then start with the carbs. Unless you are getting AT LEAST 12.7v AT THE COILS, you arent getting a good spark for sure.. and that will only compound your problems..
 
TheCafeKid said:
12.8 at 7K means you have charging problems to say the least. either your stator, or your RR are shot, or you have some corrosion going on in the wiring... Id suggest tending to that before you move on with the carbs.. Secondly, without doing plug chops in the necessary throttle positions, you truely have no idea where your carbs are rich or lean. The needle may have nothing to do with your problem, but the stumbling is most surely due to your moving the clip.. put it back, fix the charging issues, and then start with the carbs. Unless you are getting AT LEAST 12.7v AT THE COILS, you arent getting a good spark for sure.. and that will only compound your problems..
Click to expand...

I did the voltage check with the ground and power leads to the regulator, and saw that there was not a significant voltage drop, so I suspect my wiring out to the rr is good. I did replace some bullet connectors as well as running a separate ground lead from the rr mounting plate. But I do suspect my stator might be bad. I should just probably get a new one.
 
Well, I put the clips back in the middle position, and it is running much much better, but not quite there. But it is fine in the midrange now. I mean I can feel the monster within, but it misses some in the higher RPM's. I do think is is electrics now, and not jetting. So I guess I will order a Stator, as I don't think it is the RR. The stator just will not put out more than 60VAC no matter how high I rev it.
 
Last edited:
Geesh, now I don't think it is the stator. I pulled the plugs, and while the #1 and #2 looked nice and clean with a slight brown on the white insulator on the inside, numbers 3 and 4 were fouled. Number three was wet, while 4 was full of soot. Do you guys think that maybe these 2 spark plugs are bad??
 
One of the plugs just would not clean up, so I purchased a new set. I am going to remove the carbs and do a bench sync first, something I really didn't do after cleaning and rebuilding them, I just did a quick check. This time I will go through the proper procedure. :D Then hopefully after a test run, all will be good. Wow, I have never had to really troubleshoot an improperly running motor before to this extent. but then on the other hand, I have never owned a motorcycle that was 31 years old!!
 
Last edited:
slip said:
Geesh, now I don't think it is the stator. I pulled the plugs, and while the #1 and #2 looked nice and clean with a slight brown on the white insulator on the inside, numbers 3 and 4 were fouled. Number three was wet, while 4 was full of soot. Do you guys think that maybe these 2 spark plugs are bad??
Click to expand...
Could be the plugs, but perhaps you should check the plug caps resistance, (when is the last time youve replaced them actually?) I would say the coils could be at fault but 3 and 4 arent paired on the same coil so i dont think its that.. Wet with gas and you have consistant spark says to me that the air isnt getting there, maybe turn the idle air screw another half turn? black and sooty says you're getting spark, fuel, and air, but too MUCH fuel... Plugs RARELY are the culprit, but it wouldnt hurt to eliminate them from the equation. Gap correct also?
 
slip said:
One of the plugs just would not clean up, so I purchased a new set. I am going to remove the carbs and do a bench sync first, something I really didn't do after cleaning and rebuilding them, I just did a quick check. This time I will go through the proper procedure. :D Then hopefully after a test run, all will be good. Wow, I have never had to really troubleshoot an improperly running motor before to this extent. but then on the other hand, I have never owned a motorcycle that was 31 years old!!
Click to expand...
Ahhh yes, Bench sync is NECESSARY. I bet that is likely part of your problem with 3 and 4...Now, if i remember correctly, on the VMs there is no "master" carb, they can be individually set..so you'll want a baseline...A paper clip is an awesome gauge for this actually...
 
TheCafeKid said:
Ahhh yes, Bench sync is NECESSARY. I bet that is likely part of your problem with 3 and 4...Now, if i remember correctly, on the VMs there is no "master" carb, they can be individually set..so you'll want a baseline...A paper clip is an awesome gauge for this actually...
Click to expand...


Great, thanks for the info. In otherwords, I then will be able to use any carb as my baseline????
 
TheCafeKid said:
Could be the plugs, but perhaps you should check the plug caps resistance, (when is the last time youve replaced them actually?) I would say the coils could be at fault but 3 and 4 arent paired on the same coil so i dont think its that.. Wet with gas and you have consistant spark says to me that the air isnt getting there, maybe turn the idle air screw another half turn? black and sooty says you're getting spark, fuel, and air, but too MUCH fuel... Plugs RARELY are the culprit, but it wouldnt hurt to eliminate them from the equation. Gap correct also?
Click to expand...

I only have the air screws turned out 1 turn on all 4 carbies. The coils and plug caps are brand new.
 
slip said:
I only have the air screws turned out 1 turn on all 4 carbies. The coils and plug caps are brand new.
Click to expand...
They need to be turned out another half turn or so at least. Especially 3 and 4, try setting them all at 1 & 1/2 turns out.
 
slip said:
Great, thanks for the info. In otherwords, I then will be able to use any carb as my baseline????
Click to expand...
Yes, use the paperclip to gauge the opening on the slide. Stick it under the slide, the width of the paperclip should be your baseline.
 
You must log in or register to reply here.
Back
Top