GP200 Jetting & Atomiser help please

[Bugracer69]

Hi, hoping you can help/advise please.

I have a SIL GP200, it was all standard however I've just put on a TSR Evo exhaust and foam filter. It has a Jetex 22 carb
And I have tried to re-jet this - the standard jets were - 118 main - pilot 45.

I have changed the pilot to a 48 and went to a 128 main which would Rev low end but would cough and splutter when riding mid range. I then upped the main to a 132 and it's still the same.

I've read some posts about drilling the atomiser so I've taken it out to 2mm as stated and this has made a massive improvement to mid and top end. However it still feels better when the choke is on, but with the choke on or off it will not tick over and has flat spot at the start of the throttle.

Any suggestions please ?

Thanks Steve

[rosscla]

That's quite a big main for a jetex and a standardish barrel.

Boggy top end suggests too big, try a 122 or a 125.

Also if it won't tickover without choke suspect an air leak.

Jetex can be notoriously difficult to jet, try to use genuine <INC> stamped jets if you can get them. All styles or Scootopia do decent atomisers.

[Bugracer69]

Thanks for the reply, sorry my first post wasn't very clear - after drilling the atomiser it ran much better from mid to top end but still runs slightly better with the choke on. So I thought it may need slightly bigger jet or bigger centre hole in the atomiser maybe 2.5mm ?

When I had a 28 and before enlarging the atomiser it didn't seem to have the flat spot at first throttle.

Cheers