Trouble coming my way (GG300 GP-18)

[Doc Brown]

I am stumped. My GG 300GP-18 when it was jetted originally it came with:

MJ 172, pilot jet 42, NE1F neeedle in clip 3, AS was two turns out. It was runing okay (300feet, 72 F) but a bit blubbery from zero throttle to about 1/4. It produced lots of spooge during the running in phase (mix 50:1). It smoked a lot but my mates identical bike did as well.

After washing the bike I started it and let it run a minute or so, then blipped the throttle, it made a big misfire and the spark plug was dead. At this time it was a Denso 24 something. I then installed a NGK BR8ES as I had no BR8EG available.

I changed the MJ to 170 and the pilot to 40 as we had already 88F the next few days. I started and let it idle while put my gloves on, it suddenly died and I had no chance to get it back into life. I changed the spark again (BR8ES) and it started and run fine the next two hours. I tried the previous plug a day later but it didnt work.

Few days later I put new fuel in started the bike blipped the throttle a few times, another misfire and the spark plug instantly died. The bike had 7 hours on the clock.

At this time I decided to have a closer look and did this:

- checked reeds and air filter boot
- slightly reduced float height
- installed JD kit (blue needle on clip 3, 40 pilot jet, 176 MJ)
- cleaned carb with carb cleaner and compressed air
- inspected float needle
- fuel tap's flow rate
- took idle screw out to see if the little o-ring is OK
- took off ignition coil, sanded ground points
- checked all connectors and wires visually
- measured voltage while engine was running, all good
- took ignition cover off and checked for water ingress, all good
- checked ignition pick up visually and its mounting screws, all good
- installed Shido battery
- replaced spark plug for a NGK BR8EG according to owners manual


Then got on the bike and really hooned it like there was no tomorrow, I admit I was furious about all the trouble. I drove it WOT for about 3,5 miles then killed the engine while I was in gear. Checked the spark plug but it was too new I guess, it looked like it came out of the box, a bit grey. On the silencer there was a lot of spooge but I reckon its just all the shit which was in it.
After that the bike run fine, better than ever before, no blubbering with small throttle openings.

I had no chance to ride it since due to catastrophic weather, half of the country flooded. For testing I installed a used but good KTM ignition coil, nipped a bit off th elead and installed a brand new NGK (OEM KTM) soark plug cap. Bike started fine and run well in the first two gears with little throttle as well as full throttle, I couldnt test it as my neighbour was annoyed already.

Now that I wait to make a proper test ride I wonder if anyone has an idea what else I could check. My mate has an identical bike and his runs fine with MJ170, NE1F, clip 3, pilot 42.

Thanks

Doc