June 13, 200521 yr We are having difficulty with my mates bike, it seems to foul up plugs a lot (very black)! Its a Fantic 309 so I presume getting the correct jetting info may be hard so I was wondering if you guys had any tips? Is it worth dropping the needle and adjusting the air/fuel screw? If so by how much?? Any ideas guys?
June 13, 200521 yr Start at basics, Clean gas, proper oil ratio, clean air filter, new correct plug etc. etc. Then tune / jet from there. All too often we miss these basic steps and go past what the actual problem is.
June 13, 200521 yr Author Thanks Alan! We have drained the tank and put in fresh gas (we are mixing at 100cc to 5 litres) and my buddy is getting a couple of new plugs so we are ok so far but it did foul up a new plug yesterday so we thought it may now be down to jetting??
June 13, 200521 yr It will be if your not using too much oil. Running too rich. Check air screw adjustments, failing that, jetting.
June 13, 200521 yr And if it used to run well, it can't be jetting. Those little holes in those little brass thingies seldom get bigger
June 14, 200521 yr Could be crank seal too, sucking gearbox oil. Perhaps ignition is weak. Lots of possibilities, but like Alan said, start at the basics and work your way forward, making no assumptions.
June 14, 200521 yr Those little holes in those little brass thingies seldom get bigger Not true! It won't happen suddenly but a 309 is going to be 13-14 years old. I have got a 301 which was fouling plugs very quickly, changing the needle & needle jet for new ones (of the same size) stopped the fouling but also leaned things off so much that it started to pink & I had to raise the needle a notch.
June 14, 200521 yr try running the bike with a dry air filter or a filter with very little oil if you dont fancy that.i own a 94 kroo it used to do that but did what bill pye said and it worked.good luck.
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