[jonathan180iq]

The deal is that by increasing the jet size you are letting more gas into the engine than before. It's very commong to experience a loss in gas mileage when rejetting for more power. Try backing off just slightly on the jet size and see if you can maintain a proper mixture. You can find a balance between power and economy. Selecting jets isn't a written-in-stone procedure. If they make a 138, for example, I would try that. If you're get a lean mixture with a 138, then you need to stay with the 140 and you'll just have to live with the loss in mileage.

I just recently down jetted my scooter and I saw a 17MPG increase. Talk about exciting. Top speed and engine "smoothness" stayed the same. Some clown before me had it over jetted. I must be a clown too, for not checking it sooner. I dropped from a 125, which was only slightly rich, down to a 115, which is perfect.