02 YZ426 Gear ratio's

[barefootbob]

I have a friend that found a plated 02 YZ426 and we where wondering about how close is the gear ratio's on that bike.

My MX bike's, when geared for the trail wont do over 50 so I/we wanted to find out more about this bike from people that have had or still own one of these bikes.

Has anyone found a happy medium between keeping the bike geared low enough for the trail but still able to hit freeway speeds?

Thanks for your input.

Edited February 17, 2010 by barefootbob

[grayracer513]

Primary reduction ratio 62/21 (2.952)

Secondary reduction ratio 49/14 (3.500) 48/14 (3.429)

Gear ratio: 1st 24/13 (1.846)

2nd 23/15 (1.533)

3rd 23/18 (1.278)

4th 24/22 (1.091)

5th 20/21 (0.952)

Top speed at 10,500 in 5th as delivered (assuming 95% traction): 81 mph

[barefootbob]

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.

From the info you provided it sounds like the YZ426 has more of a wide ratio gearing then most MX bikes, is this true?

[grayracer513]

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.

You asked.

Primary Ratio X Trans Gear Ratio X Secondary Ratio = Overall Gear Ratio

so,

2.952 X 0.952 X 3.69 (48/13) = 10.38:1 OGR

((RPM ÷ Ratio) X tire circumference) ÷ 1056 = speed in MPH

so,

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:

https://www.thumpertalk.com/forum/attachment.php?attachmentid=10553&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.

[barefootbob]

Thank you, What I mean by over tacking is the rpm's at 60/65 for a distance of 20 or 30 miles that wont hurt the motor. Sounds like the bike is geared a lot like my Husky510. The bike will go 55 or maybe even 60 but I wouldn't ride that speed for more then maybe a 1/8 mile because it's just to many RPM's to hold for a distance. If I changed my final gearing so I could go 65 for a distance my 1st gear would be so high I couldn't hit the tight single track.

Doesn't sound like the yz426 would make a good duelsport if you plan on hitting the freeway and single track in the same ride.

[grayracer513]

Doesn't sound like the yz426 would make a good duelsport if you plan on hitting the freeway and single track in the same ride.

That's why they made the WR.