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yz125 no low down power at all

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hi. ive got a 2001 yz125 with athena barrel but sleeved to 55mm. the bike as no power attall low down. its an animal when power valve comes in and lifts the bike in 1st 2nd and 3rd and im 15 an half stone. ive been to bonsall moor track today and my bike is useless, i was working the clutch like hell to get it in the high rpm but it will not have it attall. the power low down is none existamt. i know its only a 125 but ive ridden yzs,crs,ktms and rms and they were better. my mate bought a ktm sx 125 yesterday and although its not as aggressive as mine in powervalve its 3 times more powerfull low down. please someone help???

and just to say the bike runs great on power and starts first kick everytime without fail.

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Sounds. Like jetting

I agree, I bought a cr125 that was jetted wrong and i thought my 250 lb arse was the reason for no bottom end. After fine tuning the jetting the bike had a good bottom end. I think the change was as small as leaning the needle one clip position. i knew the bike was running a little rich, but i didnt know it would make that much of a difference.

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Maybe check your powervalve to see if its working properly. Here's a way to check.

Take off you expansion chamber and take the powervalve cover off. Then you put the pipe back on and start the bike. And let her warm up and give it a few blips of the throttle. If you see the powervalve arm moving up then your powervakve is working properly.

Now if it isn't moving you may have some carbon buildup that is causing your powervalve to stick.

Also a few more things. How is your compression? And one thing like stated above is that your throttle response could have to do with jetting as well. Sometimes the two strokes can be finicky. I'd check your plug out to see what color it is.

Hope you get everything figured out man

Thanks and god bless

Alex

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I think your a.) too heavy b.) dont know how to ride a 125! 125s have little or no bottom end. You have to keep them revving all the time. I weight very close to the same w/o gear and ride at an expert level, my 125 has to sing to make it go anywhere.

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Power valve is working as it should. . Plug is a light golden brown. I know I'm heavy for a 125 but I'm well build and 6ft 4 so it's hard to just loose stones. I'm not actually fat in any way. If I can get it like my mates ktm 125 it would be wicked. If people on here rode it road they would see what I mean. When I was at the track there were a couple of lads or raced at high level and they told me it didn't sound very good.

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my compression is 160psi but even when i had it rebored and new piston fitted its always been the same

Edited by v234fdb

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my compression is 160psi but even when i had it rebored and new piston fitted its always been the same

Huh maybe check your reeds. Its possible that they may not be sealing properly.

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