I had bought 17T front and 35T rear sprockets for my 83 xs400 Seca recently. I haven't put it on yet but after reading your posting, I'm starting to wonder if it's worth it. But intentionally I did want to lower the rpm all the way down to as much gas saving I can get while cruising along the highway. But when I start reading your post about it can start losing power as trade off... i started to wonder... is it worth it? Now I'm debating on returning one of the sprocket or not, lol.[/I][/SIZE]
It won't be an exact comparison since the SECA and the MAXIM are set up so differently. The rear wheels are a different rolling circumference, the Seca has a 6 speed while the Maxim has a 5, and, I believe the rear sprockets are different too.
My goal was to have a lower "note" at cruising speed and allow me to sometimes not have to up-shift while going through town (revving high while putting along at 50 kph(30) is pretty tacky).
Simply adding one tooth to the front sprocket did this for me - shaved 400-500 rpm off in top gear (5th).
The only time I ever perceived any performance difference was when starting from a dead stop on an up-slope, and even then, it only affected the initial engagement of the clutch. Once the engine is into its power-band in low gear, it doesn't know the difference.
On the flat, I couldn't tell at all. That's the reason I did the "time-trials" on the very steep, tall hill. While it didn't accelerate to quite the same speed at the top of the hill, it was still accelerating and, had the hill been taller, it would have continued.
As to top speed, I have no idea. I never once drove the 400 over 115 kph (72).
I don't think you can lose with the simple front sprocket +1 switch. I'd be cautious with combining that with fewer teeth on the rear until you try the front only first.