• 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.

Pilot air screw setting - maximum rpm method

  • Thread starter Thread starter ianralph
  • Start date Start date
I

ianralph

Guest
I'm seeking help to tune the pilot fuel circuit.

My bike is a '79 GS1000S with a transac 4 into 1 (not sure if this is a good pipe or not), standard air filter with the lid on, Dyna S ignition with the timing spot on, standard cams with the valve clearance all within spec, and a recently rebuilt motor. I've also replaced all the O rings in the carbs as well as the ones between the inlet manifold and the head. The needles, mainjets and needle jets are all standard and the float levels are also within spec.

I've raised the needles to 4th position from the top with the plastic spacers the right way round in response to suggestions in other posts. I did a bench synch and the pilot fuel and pilot air screws are both set to 1 1/2 turns out. The bike starts (too?)easily when cold without choke.

I'm trying to use the maximum rpm method to set the pilot air screws, but no matter which way I turn them the engine speed does not change noticeably from a 1100rpm idle when the bike is fully warmed up.

Does this lack of sensitivity to pilot air screw position indicate that the fuel screws are too far out - or something else?

Thanks is advance for any help you may be able to offer.

Ian
 
Last edited:
I am not the expert, I just seem to be the first to respond.

I think the usual starting point for the fuel screws is between 3/4 and 1 full turn out. The air screws are OK at 1.5 turns.

.
 
How does it run as you ride around slowly, barely opening the throttle? Look at the plugs, are they rich after a very few minutes at very small throttle openings? Try going leaner on all four fuel screws together, then ride it again, look at the plugs again. By the way, are the carbs synched well?
 
Thanks guys - I'll try leaning off the fuel screws to 1 turn out and then have a look at the plugs after a ride just off idle. I thought it started too easily when cold....

I haven't synched the carbs yet - the suggestion from other threads seems to be that the pilot settings should be pretty right before synching.

Thanks

Ian
 
Pilot settings should be close enough to start and run, or you will never be able to do the sync. One thing I like to do when syncing carbs is to leave the gauges hooked up after the sync, then check the mixture screws, tuning for highest rpm. Yeah, there are different methods for the VM and the BS carbs, but the can both be done with the manometer connected. Then I will double-check the sync to make sure that the tweaking of the mixture did not affect things enough to change vacuum settings.

I know, it will probably never do it, but it makes me feel better.
smile.gif


.
 
A great way to fine tune the air screws is by parking the bike with the sun behind it so the needle on the tach is casting a shadow. While you turn the screws, assuming the idle is pretty steady, you can see the needle move in slight increments as the screws are adjusted.

Josh
 
You must log in or register to reply here.
Back
Top