Supermotos at Loudon

[xrocket21]

I'd kinda like to do another trackday at Loudon, but with my ATK instead of the RC51.

Im worried about the top end. The ATK is a 600cc thumper, but its current gearing limits it to 70 MAX.

What do the other motos run for a top speed? Do you guys just dog it down the front stretch and then enjoy the rest of the track? Or are they geared up for a higher top speed?

[BLACK SQUIRREL]

Get a Bigger front sprocket

[xrocket21]

I think I can only go one tooth bigger.

What kinda speeds do you see?

[SVRACER01]

motards are just north of 100 i believe
get a smaller rear.
is 1 tooth bigger all that is available or is that all that will fit? sprocket specialties will probably make you one if you can fit a bigger one.

[BLACK SQUIRREL]

motards are just north of 100 i believe

This is correct, But its not only the straight its 2 into 3 and 6 to 9 as well.

[SVRACER01]

This is correct, But its not only the straight its 2 into 3 and 6 to 9 as well.

if your moving, you can easily do 80+ from 6-9

[Awesome]

if your moving, you can easily do 80+ from 6-9

6-9 should be even faster than that. I geared the rear down to 38/39 on my crf, it tops out on power due to aerodynamics before it tops out at the engine limit. Slipper clutch saves the crank, valves, and rod. And don't let people that typically run GP shift on the track ride it.

[xrocket21]

ehh, being a difficult ATK, I think im as small as I can go on the rear already, and I can only go 1 tooth bigger on the front, and I cant get ahold of keith at american dirtbike for thast even :/

[Pittenger5]

Gear it as best as you can and do a track day. You're not gonna be racing the thing. I just did a track day where my super moto hit 108 and the big bikes were doing 160+. No biggie.

[xrocket21]

Gear it as best as you can and do a track day. You're not gonna be racing the thing. I just did a track day where my super moto hit 108 and the big bikes were doing 160+. No biggie.

yeah, theres a big difference between 108 and 70. It wount be fun winding it out banging off the rev limiter all day. Sounds like the atk just isn't cut out for it.

[Pittenger5]

I wasnt at Loudon doing 108, I barely hit 100 some times at loudon, and that was running 24s. Are you going to be THAT fast right off that youre winding it out? (no offense, serious consideration).

[xrocket21]

No, Im far from fast, the bike is just geared really low. I work in the city and it doesnt really like the 6 miles I have to go on the highway.

I have done 1 trackday on my RC, I just wasnt sure what it wasl ike on a sumo since I never have. If only a few parts of the track were a pain I could deal with it, but I just dont think the bike will do it.

The gearing is so weird, I wish it had a 6th gear. cruising, 25 is 3rd gear, 35 is 4th gear, and 45 is 5th gear. 55 isnt bad in 5th, 65 is taching, and 70 is about the max.

I just wanted an opinion on if it would work, and its sounding like it wont.

[Chippertheripper]

Do the best you can with gearing, then come outta twelve swinging, casually move inside down the front stretch and cruise, and then don't brake, just downshift into 1. That's my td routine, fwiw.

[xrocket21]

gearing options are 14,15,16 and 44, 46, 48, 50, and 52. Im currently running 15/44

[xrocket21]

I cant imagine a 14/52 gearing...

[Chippertheripper]

In my experience, the extra tooth in the front usually equals 5mph with a dirtbike. Nobody makes a smaller rear, or it isn't compatible with anything else?

[xrocket21]

In my experience, the extra tooth in the front usually equals 5mph with a dirtbike. Nobody makes a smaller rear, or it isn't compatible with anything else?

5 mph isnt much, but Id take it, it would help on the street.
with the ATK Im pretty limited on parts.

http://www.americandirtbike.com/newpage12.htm

they are talon hubs, and the motor is rotax. I have HEAR drz400 rotors fit, but I dont know. I guess I can try sprocket specialists.

[Paul_E_D]

Hell yeah, just take your sprocket to a dealer and find one that matches up. Don't let that stop you. Regear it and rip it on the track!

[rpiian]

I've had a custom aluminum sprocket made before from:

http://www.rebelgears.com/

I had them make a 26tooth rear (dropped from 33) for my KZ650. My speed is now wind limited and not motor limited. I get 50 ampg instead of 36. Win for me. A few problems though - the KZ's a slug to 30mph and it was $68...

Super fast shipping though.

EDIT: They will do ANYTHING. Trust me. If it fits on the hub they'll make it.

[Dannyf]

Sprocket specialties will make you up any gearing you need. Just remember the smaller you go in the rear the more the chains gonna ride on the swingarm.

[nt650hawk]

Check out PBI Sprockets

[xrocket21]

Thanks for the great advice

[SVRACER01]

Just remember the smaller you go in the rear the more the chains gonna ride on the swingarm.

this is a good point, not mention you may need to shorten the chain a link or 3 depending how small you go

[xrocket21]

new chain, and im almost at the smallest setting to account for future chain stretch

[a13x]

Re-gear of be in for a long day of no fun.

My 4-speed RMZ was geared 16/38 at Loudon and would hit just over 100mph. It was geared to not hit the rev limiter either, it would 'just' miss it as the bike started into T1. 19's pace.

I've ridden motards that were geared too short and would be on the rev limiter for 3/4th the front straight, T2-T3, T3-T6, T6-T9, etc. It's horrendous, plus you'll probably nuke the thing.