77 GS750 Gas fouling plugs

[Dphillips030]

Long story short... bought a 77 gs750. Carbs had pods w/ stock exhaust. Rebuilt the carbs. Main jets are 115's. Needle's raised one notch. floats at 24mm height. Ive had it running and its fouling the plugs (gas) on all 4 cylinders. I've checked valve clearances and compression and everything is in spec. Any suggestions on what to do?

[chuck hahn]

Drop the needles to the center clip is the first thing I would do to lean it out some. Stock for the bike is a 95 main and a 15 pilot. Whats size are the pilots in yours?? I thin k I have a set of brand new 102.5 mains that you can have. Between dropping the needle to its original center groove and starting with a little smaller main youll get it leaned out a lot. Too Much??? Maybe..maybe not. But starting off a tad lighter is gonna let you determine better is my point.

Where are the bottom pilot screws set at. Should be around 7/8 as a general rule from GENTLY seated.. The side mixture screws should be at around 1 1/2 to 2 out to start. Use the side mixture screws to adjust the fuel to air ratios. Turning them in RICHENS the cylinder and out will lean them out.

Shoot me a PM and I will get to the storage unit and see if i can find the baggie with the jets. In the mean time let us know what the pilot jet size is and try some of these adjustments and report back.

[chuck hahn]

Be sure the choke plungers are going all the way down too and the pods arent over oiled causing a choking condition there.

[Dphillips030]

bottom screws were turned to 7/8 out. Side screws were turned 2 out. Was planning on dropping the needle to center tonight and seeing what happens. Thought I'd get a little advice on here before getting some new jets though. Will get back with you on what happens. Thanks

[chuck hahn]

Check the plug gaps too..improper gaps make for poor fuel ignition.

[Dphillips030]

choke plungers were going all the way down as well

[chuck hahn]

Look at the plunger lifters. There are rounded raised areas that ride the edges of the plastic drum looking things. Notice these are two different sizes of raised areas..the bigger sided one goes down toward the carb body. Reason is this pushes the plunger fully seated when you push the choke lever down. If they are upside down the chokes will be held open ever so slightly even though the lever is down and it appears the plungers are fully down.

Just another thing to be aware of.

[Dphillips030]

You're exactly right. I put the lifters on the wrong way. I've already put the needle back to the center slot. Should I put it back to raised one notch or see how it does in the middle notch?

[chuck hahn]

Middle. The bigger mains gonna do its job. Its way too rich now so I dont see any reason for the clip to be down one groove at this point. Set it at the factory spot and establish a baseline withn how the plugs look..tweek from there.

[Dphillips030]

Put the needle back in it's middle position. I got it running and it idles great. I think it's still running a little rich. When I give it throttle I can see a slight mist of gas spray from the back of the carb. Should I look into going with smaller jets?

[Dphillips030]

It's also a little sluggish at low rpms but once I hit about 4k it starts to run really great

[chuck hahn]

Have they been synced with the gauges yet? Go that first and see how it goes. If its still a tad sluggish then It may need a size bigger pilot jet..obviously after it has transitioned to the needle fully it runs awesome. the pilot is effective most up to about 3,000ish RPMs and then the needle ( main circuit ) starts to take over..BUT BUT the pilot still is providing the transitional spots fuel to more smoothly make the transfer..follow me??

So by fattening the pilot jet your supplying the transition point a little more fuel so she doesnt cough.

[Dphillips030]

Gotcha. Makes complete sense. I have not synched them yet. I'll hook the sync gauges up to it and get them dialed in. If I still have the same issues I'll go up one on the pilot and see how it goes

[chuck hahn]

thats what i would do..the snyc WILL make a big change