I saw a noticeable gain in power and throttle response on the stock 26cc going from a
668 to a
990. Granted I also had an exhaust that matched the motor and could adjust my clutch engagement to match the power band. Individual results will vary, but you might be surprised at the difference it can make even on a modest engine.
As for fuel lines, I'm still running 3/16"OD x 1/8"ID lines on the stock grommet. Sure, over a long span of time the outer portion will stretch, making it look like the fuel line has been constricted, but the inner diameter still hasn't changed. The wall thickness has simply reduced. I experienced this very phenomenon this season.
Even running my 34cc with old lines I was always rich as hell, so I am in no way concerned that my engine is starved. If anything, it could stand a bit more leaning.
My primary reason to choose a
990 over an 1107 is the sand factor. If you're going to run in sand you don't want the added risk of infiltration via the choke shaft and you sure as hell want to avoid a v-stack with a built in choke. For you guys sticking to dirt and grass, it's a non issue. I like to hit the coast, and am building out my car to go bonkers on the dunes nearby, so it's a major consideration for me. Sand is no joke.