Trouble coming my way (GG300 GP-18)
 

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

I'd replace the spark plug wire. Sounds like its opening up and losing connection.

I have replaced the coil, wire and plug cap with a new KTM one I had on the shelf. But could not test yet. We have declared a state of emergency due to heavy rain since weeks.
Half of the country is flooded.

Perhaps a jetski is in order?

If your buddy has the identicle bike Why not start swapping parts. His are known to work. If you think it's electrical why not swap his coil with yours your bike should run fine his bike should run like crap if that doesn't work swap the carbs process of elimination.

That ktm part can screw anything up.

Nope, it works perfect.