82 GS750TFlat Spot 5500 - ~6500

[xkrnxjonnyx]

Just adjusted valves on my 750, dipped and rebuilt the carbs (full kit +all orings, intake boots are good), and balanced the carbs with a sync tool (1 & 4 at +2lbs vacuum than 2 & 3). I have 4 to 1 exhaust with Yoshi pipe, K&N pod filters, 127.5 main jets, stock needles (no adjustment available). The bike starts and idles smooth, but when I ride it I hit a flat spot at 5500 to around ~6500+ then it pulls again at higher rpms. I have the air screws at 3 turns, I've tried lower settings like 1.5, and I've tried the trick of turning them in individually until the engine starts running rough then turning back out just until smooth. Any ideas of what's going wrong? I'm pretty sure my gas cap valve is clear, I do have the original petcock.

 

[Nessism]

One thing is the set the sync all level. The reason the manual states to set 2&3 lower is because the stock exhaust system has a crossover feature. That said, I doubt this is the problem with your bike. Sounds like a lean condition. Try shimming the needles by reducing the thickness of the spacer on top of the clip, or remove the spacer all together and give it a try.

Good luck.

 

[blowerbike]

try a st.3 jet kit if you ever want it to carborate properly.
shim it day and night/up and down but it will never be right without the correct needles.
its a GS vaccum carb thang.

 

[xkrnxjonnyx]

try a st.3 jet kit if you ever want it to carborate properly.
shim it day and night/up and down but it will never be right without the correct needles.
its a GS vaccum carb thang.

Is it possible to purchase adjustable needles individually? I don't think I need anything else from the Dynojet kit.

 

[blowerbike]

kit only.
its only 125.00 or so.
the different shape needles require less main jet so yes you need the whole kit.
they developed and dyno tested the kits and all the parts work together.

 

[xkrnxjonnyx]

kit only.
its only 125.00 or so.
the different shape needles require less main jet so yes you need the whole kit.
they developed and dyno tested the kits and all the parts work together.

Thanks, I'll order it. Only other issue could be the petcock right?