YZ450F 08 Anybody home?

Hello everyone!

I have had YZ 450F '04 and RMZ 450 '05. Now I changed back to Yam and 08 YZ 450. But what has happened, where is the top end power? Next summer would be try to race supermoto and that bike is just too slow for that!

I have now JD-ignition box and Van Hasselt full system. But I think the biggest issue is cam shafts? I think to timing those again or should I buy new ones, example GYTR/Hot cams?

What do you think, what else to do?


Unless there is something specifically wrong with your particular bike, I think that if you run the '08 head to head on asphalt against the typical '04 from mid-RPM up, you'll be surprised to find out the '08 has a lot of top end. Mid range and the low end blast of the '04 is what they lack.

With an '08, start with a decent exhaust system, then stick a CDI from an '06 on it, and that should change the nature of the thing quite a bit. The power delivery is quite deceptive, and it's much faster than you think at first. The Euro model was a little different than the US unit, but that was mostly the pipe. Since you've basically done most of that, it may be that you want more mid range. Installing a set of '06 cams will change the lobe centering to a less top end biased setting.

That 08 power delivery especially with a stock setup was almost the ideal tight woods bike for me. Small feeling, seemless. I liken it to a big bore 250F. As stated, very deceptive. But all my friends immediately put a Dr. D on for more "bark."

You may also want to look at the carb jetting as well. How many hours on the bike?

I got a few wins on a stock 07. I also use to race a 04. If anything the 07 is weak off the corner but much faster mid to top than the 04. Unless you are running big road courses I wouldn't worry about the power too much. Stock power is fine until you get to the intermediate/expert level then you might need some more HP.

Thank you for the answers. There is a lot of power, but it feels that power curve drops too early. So I want to change engine nature a little bit.

There are only about 40 hours on bike and I'll put new piston and cam chain. Is there anything else to check/change?

What size rear sprocket?

Have Ron Hamp do some work on your head and carb and you will have the top end beast you are looking for.

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