Plugs 2/3 fouling

[Jackbob]

Hi,

Just rebuilt and installed a set of VM28 carbs to my GS1000 (78).

Rode it today for a few hours (highway) - ran really well and no problems.
Then later on took it out again for a slow ride around town -after 10 kms it started missing badly and had to nurse it home using high revs to keep in going. Idling no problem.

Checked the plugs at home - 1 and 4 are perfect colour. 2 and 3 indicate excessive richness/black colour.

I thought perhaps the coil for 2/3, but does fire the plugs OK when ground out on the head. Coils are new Dyna 3 ohm (with Dyna electronic ignition also new).

It seems to run clean when at higher revs, and idles fine as i said.
Plugs are near new. Float level set at 24mm. Carbs synced etc. New manifold o rings. New carb kits. Fuel screws set at 1 turn out.
Side Air screws at about 2 turns out.

I intend to fiddle with the pilot fuel screws next weekend - any other thoughts anyone?

Thanks.

[Guest]

jackbob, my bike starts to miss badly if i idle it or ride it at low revs for too long - due to fouled plugs (less then one minute at idle is enough to do this)
at the same time the idle itself is ok, no misfires
after i run the engine for a few mins at higher revs the problem goes away and the bike runs well, it pulls from 2k rpm in any gear with no sputter

i wasnt able to determine the exact cause of the problem

i have cv carbs, meticulously clean, synced, float levels set, and no intake leaks
the pilot air and fuel jets are the stock sizes and the pilot mixture screws are at the factory specified position
with the 4-1 exhaust that i have it should run leaner if anything, not richer
if i lean it out on the pilot screws then it pops badly on decel AND the problem doesnt go away

one thing that i havent tried is to lower the fuel level in the bowls AND lower the needles at the same time

i'm very keen to see if you find a way to fix your prob
good luck

[Jackbob]

Thanks - I will just have to work thru everything carefully i guess. Pretty sure the problem is carbs. Might start by pulling the 2 bowls and checking the jets, then lean out the fuel screws.

[SqDancerLynn1]

Have you done a compression test & valve adjustment ???

[Jackbob]

Compression is fine - 130psi on all cylinders. Valve clearances were correct 0.0015"-0.003" bought new shims to get them all spot on. However I will recheck everything i think.

Thanks