From the info you provided it sounds like the YZ426 has more of a wide ratio gearing then most MX bikes, is this true?
No, not really. Wider than many MX two-strokes, but that's typical of big displacement thumpers.
LOL, ok mr smarty pants, lol Actually I just need to know if the bike is geared for the trail, like on my bike I run a 13/48 on my final gearing. So if he was to use the same gearing we just want to know if the bike will still do around 60 or 65mph with out over tacking the motor.
Primary Ratio X Trans Gear Ratio X Secondary Ratio = Overall Gear Ratio
2.952 X 0.952 X 3.69 (48/13) = 10.38:1 OGR
((RPM ÷ Ratio) X tire circumference) ÷ 1056 = speed in MPH
10500 rpm/10.38 = 1011.56
1011.56 x 84.82 (27" tall tire X 3.1416) = 85803.56
85803.56 ÷ 1056 = 81.25 mph with 100% traction (impossible)
It's 73 mph at 90%, 77 at 95%
Or, plug in your info here, or on an online gear ratio calculator:http://www.thumperta...53&d=1242687809
Using the speed chart, you can see that the real problem is not so much how fast you can go, but more a matter of how high you rev at a cruise of say 45-50 mph. Over revving the engine under acceleration in the strict sense isn't possible, because the engine has a rev limiter built in. Of course, if you're tapped in 5th and downshift 3 gears without slowing down, that's another matter. Cruising the engine at 7000 for any length of time is probably not the best thing for it, though, and that's where "trail gearing" usually becomes a problem.