Gs1100e 1170

[Guest]

I have mkuni RS 36 millimeter smoothbores And having a very hard time getting the idle correct I have 17.5 pilot jets and 130 main jet. Bike run stron once i get off idle but a puff of black smoke Butt plugs are very dark black bike sound very lazy when i hit the throttle i was told that the air/fuel screw should be 11/2 to 13/4 out. Can someone Help me with this problem?????

[Sahi2ed]

do I need smaller main jets

[Rob S.]

So the bike's been enlarged by almost 100cc?

[Tom R]

I’m not too familiar with those carbs, but main jets won’t affect your idle. Pilot jets are what you should be looking at.... and if you still can’t get it right pilot air jets.... if those carbs have them.
I'm assuming you have pods and a pipe on that setup...... which pods?

[80GS1000]

I have RS34s on my bored out GS1000 with pods/pipe.

Your pilot jetting sounds too rich. First turn off the accelerator pump if it's enabled. Then try turning in the pilot screws 1/4 turn at a time until the engine revs cleanly off of idle.

I found that this manual was very helpful in tuning RS carbs. It's for a different model of carb but all the same principles/parts apply. https://www.mikuni.com/pdf/hs40_manual.pdf

[GregT]

Yes, disable the accelerator pump before doing anything else. You can pull the rod out which runs down into the carb body without much effort.
If you get them set up as has been suggested - but without the pump in circuit - you can then add the pump to fill in any flat spot off idle.
The pump stroke is adjustable. The less you have to put through the pumps the better.
It's quite possible it's already adjusted to the point where it's bleeding fuel all the time - causing your rich idle.

[Sahi2ed]

Yes it been bore to J&E 1170 piston kit with portend polish head big valves and cams by paul @ fast by gas V&H headers what i did was change plugs and turned the big brass screw that located on the bottom of the carburetors in front were they connected to the head. Don't know where it was before turning it all the way as y in and about 2 turns out. Now bike runs like chap at part throttle but seems ok at 3/4 to full open

[Sahi2ed]

now bike idle hi then goes down to about 1000 rpms and ba c k up to 3000rpms wh a t is causing this????

[80GS1000]

Sounds too lean now...correct pilot screw setting is somewhere between where you had it before and where it is now.

Does the engine rev cleanly off idle now after adjusting all 4 pilot screws to the same position on each carb? What position are they currently at?

Just for reference on my bored out GS1000 running RS34s I have my pilot screws set at about 1/2 turn out from lightly seated on each carb. 17.5 pilots, needles at the 3rd notch from the top, 130 mains.

As per the manual referenced above:

"TUNING THE IDLE CIRCUIT (PILOT SYSTEM)The first step in tuning any carburetor is to getthe idle circuit correctly adjusted. And, the first step inthis procedure is to adjust the pilot screw position for bestidle. Mikuni sets the pilot screw at three turns open duringassembly. This is the position we have found to be rightmost of the time. If the screw position has been altered,gently bottom it and re-open to three turns out.Next, ride the bike until the engine is at its normaloperating temperature. This may require several miles athighway speeds. If you have an oil temperature gauge, rideuntil the oil temperature is at or near 150 degrees.With the machine vertical and the engine idlingnear 1,000 rpm, adjust the pilot screw in one-half turn ata time until the idle either slows or becomes irregular. Thepilot screw is now in too far and the idle mixture is toolean. Pause for a few seconds at each half turn to allowthe engine to settle down and give a clear indication of themixture strength.Now, begin turning the screw out in half turn intervals until the engine again slows or begins an irregularidle. Count the turns between the too-lean and too-richpositions.Tuning ManualSet the pilot screw mid-way between the too-leanand too-rich positions. You may further refine the pilot screwposition with riding experience but this setting will be very close to correct."

Once you get the idle mixture correct, use the idle speed knob on top of the carbs to set your idle speed to about 1000 RPM.