Crf450r low on power

Hey guys, need some help. Really scratching my head on this one.

03 crf450r project.

Brand new 13:1 wiseco piston in it. Bike will only start by push starting it. And when it does start, seems like it's super low on power. Feels like I'm riding an underpowered Harley. No hit at all. Piston hasn't even been broken in yet, that said, haven't revved this thing up either, it just feels super weak.

What would cause these symptoms? Could it be the carb? The bike is popping a lot but I didn't think the carb really could change the power this much and even have the bike run? Before you all ask, the timing is right, I've triple checked that and the valve gaps are in spec.

Only thing I can think of is carb or cdi but I'm confused on this one for sure.

What do you guys think?

Your cam timing is off one tooth, or you put the slide plate back in the carb upside down

Maybe you installed the timing chain auto-adjuster without retracting the spring???

Have you compression tested it. Never trust someone else's work

Yep, check the timing chain tensioer, the cam timing itself too. You did something incorrectly somewhere. If you tried to set the cam timing the way the book tells you, Im almost certain you missed it.


When I do them, the last thing I put on is the stator cover. If you look, there's a mark on the flywheel and an arrow on the engine that marks TDC. With the stator cover off, its impossible to miss the timing unless youre drunk or not trying. And If you leave the top end off to put the engine back in the chassis, the stator cover is still the last thing I put on. Although, I'll put the head on and the valve cover before I put the engine back in. B)

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