[ScotD]

Mech,

Thanks for your posts both to this and my aerodynamics thread. On that one you mention that your trike project is 1100 lbs, so I can easily see that you'd see the Grom as lacking adequate power! Since using a Grom I expect my trike's weight would be under 300 lbs (vs over 400 if using the 250); and since the Grom reviews suggest 60mph stock and my trike would be far better aerodynamically, I think it would have adequate power for my desires and use (though greater power would create additional versatility). Yes, final drive ratio is important . . . and yes, availability of a Grom is problematic.

The California Commuter, built in 1980 and setting world mpg records that year, started with a Honda Super 90 engine, and they got highway speeds and something like 186 mpg. To make it legal on the freeway they had to increase the power, using a stroke kit to bring it up to 130 cc. Though there was no significant weight change, the mpg went down to under 160mpg (they had expected an even greater change).

So since using a CBR250R would result in at least an extra 100 lbs weight, as well as twice the cc's, it seems very likely that mpg would be significantly lower than using a Grom . . .

But the truth is, that for me, this is all speculation - somewhat educated guessing!

Any further input???