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Unable to reach top rpms after new top end

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I have 02 125sx and my friend recently helped me put a new top end on it.

Fired up fine on the second kick, no apparent problems at all.

Then took it for the break in procedure to the nearest ohv park.

It was there when I noticed that the motor would not reach the top rpms, in other words, it would not scream even at wide open throttle, it will quickly reach the mid range and it just stayed there.

It doesnt make any weird sounds, its not lacking any noticeable power from the midrange down and its not fouling any plugs. It just wont reach the top rpms.

Anybody knows what the problem could be? jetting, pvalve, piston ring maybe?

Btw, During the break in procedure I did not gave it wide open throttle, short shifting, etc. It was after the break in when i noticed the problem.

Thanks in advance!

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PV linkage not right. Remove L side cyl inspection port, start bike and rev it. You should see one of the two pieces of metal sliding vertically. If it isnt then remove pipe, drain water, unbolt cyl(leave head on), remove R side cyl inspection port and then lift cyl an inch or so. Then thru the port you can see the fork n ball and get them together as you lower the cyl back down.

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I have an 02 125SX as well. This definitely sounds like the powervalve. Follow Mikes instructions and you should be ready to rip!

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I did the same thing when I did the last top end on my 01 200. It's really easy to do! When you're reinstalling the cylinder, pay CLOSE attention to how the rod and the arm of the PV meet up.

I actually did something else, and it's really stupid and weird, but worth looking into ... you have to use the shortest bolts on those little sight window covers. I grabbed one that was a hair too long, and caused the arm to hang up and not open the PV all the way.

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Thanks guys,

it was the pv. The same problem as Firecracker's with the long bolt.

Fixed it and now bike works awesomely!

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I did the same thing when I did the last top end on my 01 200. It's really easy to do! When you're reinstalling the cylinder, pay CLOSE attention to how the rod and the arm of the PV meet up.

I actually did something else, and it's really stupid and weird, but worth looking into ... you have to use the shortest bolts on those little sight window covers. I grabbed one that was a hair too long, and caused the arm to hang up and not open the PV all the way.

Firecracker, you're my hero! A girl that rides and works on her own bike! :) ........Where have you been all my life. :D

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Thanks guys,

it was the pv. The same problem as Firecracker's with the long bolt.

Fixed it and now bike works awesomely!

I'm SO glad I'm not the only one who's done that!!!

Firecracker, you're my hero! A girl that rides and works on her own bike! :) ........Where have you been all my life. :D

Hehe, I'm too much trouble, I promise. But thanks. :worthy:

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Hehe, I'm too much trouble, I promise. But thanks. :)

I believe you are correct, but that's a great tip, and one I'll have to file away for future reference.

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