Rebuilt carbs, now a question about tuning.

[Anonymous]

Alright, I rebuilt the carbs on my 78 GS1000 and in the factory manual under tuning it says NOT to touch the mixture screws and such....well I think I did

There were 2 screws which were spring loaded and are accessable from the outside (one on the bottom, and one on the side). My question is, how should these be set? I tried to put them ABOUT where they were when I took them off, but Im not perfect. Did I just cause myself more headaches?

[KEITH KRAUSE]

See my topic about original settings on these screws in the "tips and tricks" section.

[Anonymous]

Well, that helps alot....now the next question. HOW do I TUNE them?

The only instructions I have are the ones in the factory manual (which tell you not to touch them, so they offer no help). What is the proper procedure to tune them (or at least an idea). Im not sure what u mean by "able to achieve the highest RPM" and stuff like that, or HOW one would go about doing it.

If there is another post with the instructions, please point me to it. Im not stupid, and know what your talking about, I just need someone to tell me the order of operations the first time so I know what to do.

*edit*
Ok, after reading it again, here is my ***idea*** of how I should do it.

Get the carbs on and synched (shouldnt be a problem)
Ride around
Check plugs
If too rich, adjust the pilot screw (in to lean, out to richen I assume).
Clean plugs and go for another ride.
Repeat until all plugs are the right color.

If im missing something here, please let me know (also let me know WHERE the air screw comes into play and how to set that one).

Thanks,
Dan

[earlfor]

Re: Rebuilt carbs, now a question about tuning.

What do you mean by "rebuilt the carbs"? Does that mean you completely dis-assembled the rack, removed every part from the carb bodies, soaked the bare bodies, replaced all "O" rings and gaskets and re-installed new jets and re-set all needles. Do you have the stock exhaust pipes and airbox with filter. What main jet size is in your carbs?

I can give you step by step instructions on how to set them up, but I need to know what you have done. I seem to be doing a fair amount of carb work on GS1000's in my shop lately. :-)

Earl


[quote="DDMan"]
Alright, I rebuilt the carbs on my 78 GS1000 and in the factory manual under tuning it says NOT to touch the mixture screws and such....well I think I did

[Anonymous]

Well, I did pretty much what you mentioned, but cut a few corners :?
Heres what I did:

Completly disassembeled the carbs, removed everything off the rack
Took out all the jets/needles from each carb,
Cleaned everything with carb cleaner (went through 2 cans for 4 carbs, so I Cleaned them really well) and wiped everything clean,
Then put the ONE new o-ring that came in the K&L kit (went on the air screw on the outside)...The other 2 o-rings I just cleaned and put back on.
Put all new Main jets, float nedles, and replaced anything that came in the K&L kit.
If there wasnt a replacement, I just cleaned it really well and put it back in.

I also am bone stock, stock pipes and stock filters, so I assume the main jets were stock, since I used the ones that came in the K&L kit.


EDIT: Just went out, and sure enough there are little tabs on both the pilot and air screws. I set them as I thought they should be (1/2 turn out on the pilot screws...to line up to a tab, and between 3/4 and 1 1/4 turns on the air screws to line up to those tabs).

[KEITH KRAUSE]

OK. I think a 1/2 turn out on the pilot screws (underneath) is not enough.
Once you've moved the screws it's not certain how to re-set them as my other topic says. You can't know which "side" of the screws slot should be in line with the nick. It's more likely the screws would be closer to their original settings if you turn them all 180 degrees out more, or 1/2 turn more. All you can do is test the pilot circuit by riding a few miles at 35/40 mph in top gear and get plug reads. Turn the pilots in small increments until the plugs look good. It's not unusual for them to end up in different positions. Example: 1, 1 1/4, 1 1/8, 1. These screws are for fine tuning each cylinder, that's why they are commonly set at different points.
As for the side air screws, put the bike on the centerstand and warm it up first. Turn two screws in 1/4 to 1/2 turn increments until you hear the rpm's max. Fine tune these two. Then adjust the other two until the rpm's max. Fine tune them. Now re-set the idle to 1,100 rpm by adjusting the idle screwknob. After this, you can synch the carbs. Make sure the ignition is timed correctly before synching too. Don't go out testing until all this is done first.

[earlfor]

DD, I havent forgotten you. My computer at home went down last night.
I plan on getting it up and going again this evening. I'll post you answer as soon as I can.

Earl

[quote="DDMan"]Well, I did pretty much what you mentioned, but cut a few corners :?
Heres what I did:

[Anonymous]

Alright, sounds decent. Few more questions though.

1. The bike isnt street legal, so riding at 35-40mph isnt really possible. Can I do 25-30 in 4th gear?

2. When you say "max out" the RPM's, do you mean just watch them and stop when they reach the highest RPM?

3. As its set right now, the throttle doesnt really rest on the idle screw, the cylinders in the carbs are resting on the base of the throttle opening. Is this how it should be, or should the throttle be stopped by the idle adjuster?

[KEITH KRAUSE]

Alright, sounds decent. Few more questions though.

1. The bike isnt street legal, so riding at 35-40mph isnt really possible. Can I do 25-30 in 4th gear?

2. When you say "max out" the RPM's, do you mean just watch them and stop when they reach the highest RPM?

3. As its set right now, the throttle doesnt really rest on the idle screw, the cylinders in the carbs are resting on the base of the throttle opening. Is this how it should be, or should the throttle be stopped by the idle adjuster?

Yes, you can test the pilot circuit by going slower. 3rd or 4th gear is fine too. I like to test by simply riding the bike easy and at a steady throttle position. The whole idea is to minimize any overlap effect from the needle circuit. So you want to open the throttle just a bit beyond closed. Just enough so you can putt around slowly.
By max out the rpm, I mean LISTEN for the highest rpm's. Turn 2 side air screws as a "set" to more easily hear the rpm's rise. By a set, I mean turn one screw and then quickly turn the second screw on the two carbs that have their air screws facing you. Turn the screws in equal amounts. You will reach a point where turning the screws out more will no longer make the rpm's rise. You want to set the screws at the point where the rpm's rise as much as they will go but no further. Just get them close, they don't have to be perfect. Then do the same thing to the other two screws on the other side. After you've set all 4, adjust the idle to 1,100 rpm's with the idle screwknob.
Before starting the bike, give the screwknob 2 or 3 turns or so after it starts to make contact with the throttle pulley. If it's not touching, the bike won't start or idle.

[earlfor]

Well DD, it only took all evening to get this electronic bucket of bolts functioning again. Sheesh!

Ok then. I know how difficult it is to get the carb stack on and off
the 1000, but what can I say? :-)
1. Remove the carb stack
2. Turn the carbs upside down and set the float heights. Reinstall
float bowls.
3. Slowly turn the fuel pilot needle (on the bottom of the carb/float bowl)
in until you feel it lightly seat. Turn it out 1 1/4 turns.
4. Turn the airscrew in until it seats. Turn it out 1 3/4 turns
5. Turn the idle adjustment knob (between 2 and 3 cylinders) out until
it no longer makes contact with the throttle linkage.
6. Remove the throttle return spring from the carb linkage.
7. On the top of the slide in each carb, there is a brass adjustment
screw with a jamb nut. Loosen the jamb nut and turn each adjuster screw
lightly all the way down. Back it off two turns. Finger tighten the
jamb nuts to hold that setting.

Close the throttle linkage using your finger and hold down the linkage
lightly in the closed position (slides down) Take the shank of a 9/64"
drill bit and insert it between the skirt of the slide and the bottom of
each carb throat on the airbox side. If you find a slide skirt that is
too low to allow the 9/64" bit between the skirt and carb body, turn the
idle adjustment knob in until that lowest slide raises enough to barely
allow the drill bit to be inserted when the throttle linkage is held in
the full down position.
This will be considered the control/baseline carb.

Once you have a carb set to the 9/64" baseline, do not turn/touch the
idle adjustment knob again. On the remaining three carbs, Use the
brass adjuster on top of each slide to set the slide to 9/64" clearance
when the throttle linkage is held in the closed position. Finger tight
the jamb nut to hold the setting. When you have finished this part, all
slides should have a 9/64" opening between the skirt and the carb body
when the throttle is held closed. When this is correct, turn the idle
adjustment knob in about three turns. (you should be able to see all
four slides slightly raise in unison when you do this)

8. Reinstall the return spring.
9. Install the carbs on the bike
10. Leave a slight amount of slack in the choke and throttle cables
once installed Check that when the choke is off, the choke arms on the
carbs are fully seated/off and that the throttle grip when closed allows
the linkage to return to fully closed.
11. Remove the vacuum plugs on the underside of the carb intake between
the carb and cylinder head and install the 4 mm adapters for the vacuum
lines for the mercury carb stix/vacuum guages.
12. If using the bikes fuel tank as a fuel supply (I do, I just use
long fuel and vacuum lines so I can sit it on a stool beside the bike),
be sure to install the vacuum line to operate the petcock. If using a
small test tank and gravity feed, then plug the vacuum line on the carb
that normally would be connected to the petcock.
13. Start the bike and set the idle adjustment knob so that the idle
rpm is 1200. ( it make take a few minutes for it to warm up enough to
hold a 1200 rpm level)
14. At 1200 rpm, you want the vacuum on each carb to be 8 inches of
mercury. Turning the brass adjusters on top of each carb in will lower
the slide and increase vacuum on that carb. Turning adjuster out will
decrease vacuum. Adjustments are usual made in small amounts and I
usually adjust the carb that is the farthest out of synch. There is no
particular sequential order. You want to get all carbs at the same
vacuum level first. With each adjustment, rpm may climb or fall.
Between each adjustment, reset the idle adjustment knob to always
maintain 1200 rpm.
Once all carbs are drawing the same vacuum , lower or raise the vacuum
level bit by bit across the board until all carbs are drawing 8 inches
@1200 rpm. Holding the slotted adjusters on top of the slides from
turning with a
screwdriver, gently snug the jamb nuts down to hold the adjustment
(probably about 6 ounces of torque is all that is needed on the adjuster
jamb nuts.......they will strip easily....careful! :-) )

That should do it. :-) :-) :-)

Earl

[Anonymous]

Great post Earl!
Would I use the same drill bit size and screw turns on my 82 650gl?

[earlfor]

Yes, you would. Vacuum levels and baselines will be the same.

Earl

Great post Earl!
Would I use the same drill bit siz
e and screw turns on my 82 650gl?

[Anonymous]

Thanks alot!
You rock

[Anonymous]

Ya...I agree. Earlfor is the man when it comes to fixing these things! Im SOOOO glad you guys are willing to help out when it comes to fixing up these old beasts.