No acceleration above 4000

[Guest]

Hi folks,
I have a 79 GS1000 that I added a Dyna S ignition, the timming is set 1-4 "F" and 2-3 "F" at 1200rpm and the "I" marks line up at 2500rpm. I also cleaned the carburetors and replaced the rubber manifolds and o-rings. Last but not least, I added K&N pods and rejetted the main jet to 110.
In the lower rpms the engine runs fine, but lays over when the throttle is twisted. What did I miss?
Thank you,
Ken

[JTGS850GL]

You missed doing some plug chops to see how lean/rich you are on the mains.

[howardshane2]

Did you go to a richer needle clip position as well since you went to K&Ns?

[gsrick]

You missed doing some plug chops to see how lean/rich you are on the mains.

Yeah I'd say your starving for fuel. If I get time tomorrow, I'll pull the carbs on my '78 and see what mains it has.

[Kat4568]

Thanks for the replies. I will pull the plugs tomorrow, then check the float height, and raise the needles 1 clip.
Thanks,
Ken

[JTGS850GL]

Thanks for the replies. I will pull the plugs tomorrow, then check the float height, and raise the needles 1 clip.
Thanks,
Ken

Pulling the plug isn't going to help. You need to do a proper plug chop. What that means is you run the engine at the desired RPM and load. Once there for a few seconds do a sudden kill. Kill your ignition (red switch on right side) and pull in the clutch. Come to a stop and THAN pull the plugs to see what their condition is. That will tell you the cylinder conditions at that RPM/load. In your case it would be at the 4000 RPM area WOT. Running the bike, coming home and pulling the plugs will give you no information.

[Kat4568]

Thank you for your help. The solution was to lower the e clip on the needle to the bottom groove. This Sunday I plan to go to the mall early and do plug chops. There will be no cars and a big area to test.
Thanks again,
Ken

[mrbill5491]

Thank you for your help. The solution was to lower the e clip on the needle to the bottom groove. This Sunday I plan to go to the mall early and do plug chops. There will be no cars and a big area to test.
Thanks again,
Ken

To do a proper plug chop, you need to be out on the highway at speed for several miles. Doing it in a mall parking won't tell you anything.

[JTGS850GL]

To do a proper plug chop, you need to be out on the highway at speed for several miles. Doing it in a mall parking won't tell you anything.

Agreed. You need to be in the power band you're testing and be there for several seconds. Get out on an open road and do the tests as needed.