Athena 490 big bore kit need help???

[Red Juggernaut]

I recently purchased the athena big bore kit on my 07 trx450er. Im not very happy with the bikes performance.....Its slow i dont know why. I have a 04 trx 450 with stage 2 cam, high comp. piston, port polish, cdi etc. It walks on my 490. Motor work built by same person. The 490 also has the same parts as the 04.. cam, ported polished, cdi. What could be wrong with my 490?
JUG

[pro-rider46]

did you build it? is it jetting right?

[rt20ps]

The biggest mistake people make with big bores is in the jetting. Your 490 needs less fuel than the stock bore. Try leaning it out to gain some power..

[dtzalba450r]

dont forget that the gearings different on both bikes...

[Red Juggernaut]

No i did not work the motor... But a very popular builder did. He built my 04 n love it. As far as i know the jetting is right, sounds like it. i have a 182 main in the carb with a fmf power4 powerbomb header. I will try a smaller main but how small? The HRC air box lid is on the bike. Is the tranny gears different? I changed my sprocket sizes. Both bikes are the same, 15-36.
JUG

[310ESR]

Take the 07 to 14 in the front. The gearing is different on 06 on.

[Red Juggernaut]

I understand the gearing is different on the different years... Im trying to explain that both of my bikes are geared the same why is the bike with less mods out running my heavily modded bike. The power from the 490 is not at its peak and im trying to figure out the jetting like rt20ps said. But i dont know how much smaller i need to go.
JUG

[dtzalba450r]

Even though the sprockets are the same...the actual tranny gears are different.

Dont assume because the newer bike has more displacement that its actually faster jmho.

Have you considered the rider being the difference in the race?

Do you have the same exhaust on both bikes?

[310ESR]

Hey juggernaut some the gear ratios though out the tranny so thats why the final drive ratio from 04-05 are different then 06 on.
Trust me just because a bigger engine can pull more gear doesn't mean it shoud. My DASA 450 can out run a Duncan 480 of my buddys for the same reason.

[Red Juggernaut]

Ok, now everything makes sense to me. looks like i will need more work done to my bike. Thank you guys for the help.
JUG

[jjm400ex]

a 182 mj is to big, try 165-170, i run a 165 on my 06 modded 450

[Red Juggernaut]

OK ill try with the 170 first to see how it feels.
JUG