Abgeschickt von Matthias (NZ) am 19 April, 2005 um 15:28:40:
Antwort auf: Jetting von Matz Rosenquist am 19 April, 2005 um 09:01:54:
: Hi All!
: Problem: Way too black sparkplugs, sooty and black.
: Conditions: 45 idle jet, 160 main jet, 2.64 nozzle jet, needle in ordinary position, 1043 Q-Tech engine, 320/3 canshaft, 44 mm inlet valves, valve clearance 20/15, NGK 5 KOhm resistor caps, NGK BP6ET plugs, ignition timing set to 3-4 degrees static, HPN open airfilter, standard exhaust system
: I've tried raising and lowering the needle withot result, same goes for nozzle jet having tried 2.64, 2.66 and 2.68 in various combinations with main jet and needle position. Choke system works, new gaskets.
: Any ideas anyone??
Plugs black after what speed? Have you checked them after a good midrange run, i.e. riding along at, say, 110kmh then cutting the engine and checking the plugs?
I had exactly the same symptoms for years (similar jetting to yours): After a city trip the plugs were solid black. After a midrange run the centre of the plugs looked about right but deep down the centre insulator and around the outer ring it was still pitch black.
It turned out to be the O-rings around the idle jets. They are round and soft when new, but mine were squashed square and hard. After replacing these the plugs look fine after any type of run, and the influence of the needle-position and needle jets was more marked.
Not sure, when you said "new gaskets", whether you changed the O-rings as well? Worth a try (also those of the needle jet holder).
Cheers
Matthias