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03 kx125 powerband problems

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I just picked up an 03 kx125 and when riding if I go full throttle its takes a long time to get to the powerband and then finally hits the powerband and it seems to bog a lot it has full pro circuit is the problem my jets? Plus the bike sounds like its always bogging if I let off the throttle and get back on it

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For me, it sounds like it's time for a top end rebuild. My kx did this. I have a video of it on YouTube as well.

It has a new top and bottom end and lots of compression and my friends cr125 that blew the next day cuz it had no compression hit the powerband

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Then yes, it may be the jetting. Play with it and see where it's heading. Also make sure the reeds are intact and there's no air leaks.

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Sounds like you have a powervalve issue. Linkage, governor, etc. Also, the PC pipe on these bikes absolutely suck. Get yourself an FMF and you'll understand my meaning.

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Sounds like you have a powervalve issue. Linkage, governor, etc. Also, the PC pipe on these bikes absolutely suck. Get yourself an FMF and you'll understand my meaning.

How would I go about fixing the power valve problem or checking to see if that is the problem

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Unfortunately, you have to remove either the cylinder or the engine to check your powervalves themselves. Since the frame is in the way. You'll have to remove the right side case to access the governor.

 

But first thing is to remove the cover on the right side of the cylinder where linkage is at. Start bike on stand and give a few WOT revs to see if linkage moves.

 

Now, my first few questions: Is the first time you ran it with all the parts on it? New pipe, rebuilt etc. Or have you had the bike awhile and it just started doing this?

 

I will tell you the PC pipe has a very late powerband and is an all-top-end pipe.

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Unfortunately, you have to remove either the cylinder or the engine to check your powervalves themselves. Since the frame is in the way. You'll have to remove the right side case to access the governor.

But first thing is to remove the cover on the right side of the cylinder where linkage is at. Start bike on stand and give a few WOT revs to see if linkage moves.

Now, my first few questions: Is the first time you ran it with all the parts on it? New pipe, rebuilt etc. Or have you had the bike awhile and it just started doing this?

I will tell you the PC pipe has a very late powerband and is an all-top-end pipe.

I just bought it with about 10 hrs on new rebuild but I think the jets are in correct i have to check

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Yes check the jets. But If it runs ok but feels like a turd. The scrap that PC pipe and get a stocker or FMF. I couldn't believe the difference on ours. It was like a whole new bike. I'm gonna say that PC didn't do their homework on this bike too much since the 04's were coming out and used a different design altogether and 4 strokes were the new thing during this era. FMF stayed loyal.

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