Big Bore kit for a RMZ-450?

MXracn746

MXracn746

PR Addict
I'm going to get a big bore kit for my 07 RMZ. I've thought about it and I'm going against the KX500 as I don't think I've got the strength to hold to it anymore, but want the more torque. I like the RMZ, but realize I'll have it for only a season or two more before I get a newer one. So, what big bore kit do you recommend. I was thinking about the athena 475cc kit. I just want a bolt on kit and really don't want any machining. I'll be doing new cam chain and guide and probably valves and mabey a Hotcams cam this winter.
 
Cams alone really make that much a diff? Wanting more power and torque. I'm gonna be getting piston anyhow. Which cam?
 
Yes, from what I'm told Matt already put one in it before I bought it. Now it could be worn or need rings or something. But I want it to bark like the '03 YZ450F I had. That motor was a beast and it was stock!
 
I figured you opted out of a KX500 because they handle like a school bus!

If you want more torque, a bigger bore will do just that. You don't necessarily need more compression either, as that may stress the connecting rod. More torque will let you run taller gearing and realize lower RPM. That in turn will unload the chassis and make the bike a lot easier to ride.

The 03-05 YZ450s were handfulls and a lot of fun in the right conditions. I am not so sure those were the hot ticket for actual riding / racing. Well, maybe off the line, but 10 minutes into a moto?
 
I recently installed an Athena 490 kit in an 08 rmz450. Only reason was the cost dif from stock. The crank bearing went bad and splattered parts all over the cylinder wall. It still ran but sounded horrible. Only did break in rides as of now but man does it have tons of torque. Feels like a 500 of old but without all the hoopla.
 
what about trying to find a KTM 380, all the torque of a 500 but alot narrower and lighter feeling. I'm not giving up my KX 500 but a KTM 380 would be a cool second bike. I still want a CR 500 too.
 
hey guys ! i got to rebuilt almost complitly the engine of my rmz450 07.. i want to go with the hotcams and bigore kit 490, high compression piston and heavy duty conecting rod and crankshaft.. you guys got any suggestion ?? im looking to reach the highest performance possible with a good lifetime too.
 
I saw a transworld ad were it said that it increased the power in all parts of the curve. But, it took alot of lifetime off of the motor.
 
s!ckbr1 said:
hey guys ! i got to rebuilt almost complitly the engine of my rmz450 07.. i want to go with the hotcams and bigore kit 490, high compression piston and heavy duty conecting rod and crankshaft.. you guys got any suggestion ?? im looking to reach the highest performance possible with a good lifetime too.
Click to expand...


Are you guys on crack? What the heck do you want to mod a 450 for?!! Jesus. Most of the power isn't usable for us weekend warrior Joes anyway! 500 2 strokes vibrate your arms to sleep....you guys are nuts!

Just go pick up a 13 yz450 for dirt cheap and get the gytr tuner and tune that FI so it barks and rips your arm off with the stock motor......i'll detune the engine though. ;)
 
I was thinkin the same thing! Who needs more power outa a 450! Spend that money in suspension or wheels or ttiple clamps or somthin!
 
when im next to a guy who weighs 160lbs and is also on a 450, sometimes i wish i had a big bore!
 
You must log in or register to reply here.
Back
Top