baseline jetting

[gearjammer]

Just wondering where to start. I've never worked on m/c carbs. I've got a 78 gs1000 with individual air filters, 4 into 1 pipes and a muzzy muffler.

[Big T]

120 main

Raise the needles one notch

Maybe a 17.5 or 20 pilot jet

[cowboyup3371]

Honestly, why not take your carbs off and follow the cleaning instructions on Basscliff's site. While you are at it, you can record what you have in there. End result - perfectly cleaned and rebuilt carbs with a knowledge of your bike.

[KEITH KRAUSE]

Just wondering where to start. I've never worked on m/c carbs. I've got a 78 gs1000 with individual air filters, 4 into 1 pipes and a muzzy muffler.

If carbs are clean, floats set to .95", fresh inner o-rings, fresh manifold o-rings and good manifolds and all other tuning correct such as timing advance and valve clearances and clean air filters...
If you use separate jets and try to keep the stock jet needles it should run well with 130 Mikuni mains, jet needle e-clip in position 5 (bottom) with an approx' .022" jetting spacer (standard jetting spacer used for 1/2 position changes) directly on top the e-clip. That would be called position "4 1/2". If stock, the jet needle will have 5 grooves in it. Be SURE the thicker factory plastic spacer goes on top of the e-clip and the thinner plastic spacer goes under the clip.
Try keeping the stock #15 pilot jets and adjusting the pilot fuel screws (underneath/engine side) to 1 1/2 turns out from LIGHTLY seated to start. If not rich enough go ahead and try up to 3 turns out. If no joy by 3 turns out then you'll need #17.5 Mikuni pilot jets and return the screws to about 1 turn out and test.
Initially set the side air screws to 1 3/4 turns out. Once the bike is started and fully warmed up you will adjust the side air screws using the highest rpm method found on this site with a search.
REMOVE the two upper floatbowl vent lines and leave the ports open to breath. This helps avoid fuel starvation caused by poor bowl venting especially during windy days.
A stage 3 jet kit from Dynojet will work better because they use a better jet needle. They use a 138 DJ main but that's technically the same as a 130 Mikuni jet because they use different methods to size their jets. Their kit also runs best with the stock pilot jets. If you use the DJ kit, then most common jet needle e-clip position is #4 from the top (DJ uses 6 grooves on their needles). DJ says to remove the two vent lines also.
Be aware you must carefully bench synch the carbs and once started you should vacuum synch the carbs with a quality tool. Once final synch is completed, re-check the side air screws for highest rpm.
Fine tuning the screws will probably be needed. Any jetting questions you have please make a new thread so we can help.