125cc no powerband help!

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Yamyzfrrider

Member

Jul 25, 2004

5

0

• Jul 25, 2004

• #1

I just rebuilt my old 1988 yz 125cc bottom and top end. Everything is running, but I don't think the bike is running properly. :bang: What happend was about 7 yrs ago I blew the bottom end bearing and the bike has been sitting since until about 1 month ago. I replaced the rod and top end with a weisco piston and hot rod kit. I've been riding the bike a lot and it runs good but It has no power band whatsoever. I know my bike has a power band because before I blew the bottom end it hauled butt, but now it seems really slow. Could this be a carboretor problem or a valve problem? Any help would be great. Thanks.

 

elf

Member

Jun 7, 2003

695

0

• Jul 25, 2004

• #2

Explain what you mean by no (power band), Where does it run good? and what is missing ? Top end power? low end?

 

K

KTA

Member

Jul 14, 2000

287

0

• Jul 25, 2004

• #3

I'd bet its your carbs. After sitting for 7 years (or even a few months) they tend to get gummed up. I bet if you gave your carbs a good cleaning, and possibly a rebuild kit (new float, gaskets, etc) it would get it's groove back.

 

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Yamyzfrrider

Member

Jul 25, 2004

5

0

• Jul 25, 2004

• Thread starter
• #4

elf said:

Explain what you mean by no (power band), Where does it run good? and what is missing ? Top end power? low end?

Click to expand...

It just feels like there is no top end power at all. Low end seems to be fine.

 

elf

Member

Jun 7, 2003

695

0

• Jul 25, 2004

• #5

If your carb is clean, then your problem is with the power valve. Its not opening all the way or not at all. I had the same problem with a 89 yz 125. Check to make sure every thing is hooked up correctly.

 

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hrc125rider

Member

Aug 22, 2003

47

0

• Jul 25, 2004

• #6

im going along wit that the accuater on the power valve is seized b/c i had the same problem with my 88cr125

 

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Yamyzfrrider

Member

Jul 25, 2004

5

0

• Jul 26, 2004

• Thread starter
• #7

I finally fixed the problem. I took off the exhaust and got a flash light and looked in the exhaust port and found out that the valve was positioned 180 degrees out of place. I took off the push rod and rotated the valve 180 degrees back to normal and boy does my bike haul butt now. Thanks guys for the help. I appreciated it.