Bike all of a sudden has no bottom end, even in first gear!

fatboyslim

Member
Apr 11, 2006
255
0
My Ktm is a power house for a 125. But one time I was out riding, not too hard. But then I started to pin it in 3rd gear and it all of a sudden sounded like an 80 and there was a loss of power. It sounds like a hornet in a tin can inside of my pipe. I just put a new vertex top end kit in it, I run the oil at 32:1 or 40:1, I put a new clutch in it, spark plug has plenty of spark, the power valve and reeds work fine. And I also clean out my carb like 3 times. The only change I made was leaning out the needle to one position (2nd) because black sludge is coming out of my silencer and I repacked my silencer.

Then just the other day I took it for a rip and it started to bog and miss terribly on the low rpms, the it would hit the high rpms just barely and fall off again. Please help. I need to ride.
 
Last edited:

sick 96 250

Damn Yankees
Member
Jul 16, 2004
1,207
0
move the needle back and see what happens? Moving it one clip could of leaned it out to much
 

Masterphil

DRN's Resident Lunatic
Member
Aug 3, 2004
1,003
0
What jetting are you currently running?
What is your compression (psi)?
Are you sure you didn't install the clutch wrong?
How fresh is your silencer packing?
Did you make sure the X value was in spec when you installed the new piston?
Did you clean the powervalves?
Where do you have the powervalve adjusted to come on?
 

dante

Member
Mar 24, 2004
555
0
After my last top end, my bike did the exact same thing... It may sound funny, but a fresh brand new plug had me up and running again... I took my bike out ran it around, everything was fine and all of a sudden loss of power... Hitting, then missing just as you describe... I pulled the plug, turned out the lights, kicked it over; I saw a spark... But after going through everything I could think of, it was a fouled plug...
 

Masterphil

DRN's Resident Lunatic
Member
Aug 3, 2004
1,003
0
dante said:
After my last top end, my bike did the exact same thing... It may sound funny, but a fresh brand new plug had me up and running again... I took my bike out ran it around, everything was fine and all of a sudden loss of power... Hitting, then missing just as you describe... I pulled the plug, turned out the lights, kicked it over; I saw a spark... But after going through everything I could think of, it was a fouled plug...

A result of too-rich jetting or a too-cold of a heat range plug for your riding conditions.
 

ComradeMikhail

Mi. Trail Riders
Member
May 2, 2005
244
0
Keep in mind: Just because a plug gets a good spark outside the cylinder, doesn't mean it always will inside. The spark may seem fine outside, but not enough to not foul out while inside the cylinder. If you havn't, I'd change the plug out.
 

OTHG_DAVE_858

Member
Feb 18, 2005
193
0
You might want to check and see if your reed is OK. Mine had a chip off the corner and did the same thing. After I put a fresh top end in and noticed the reed was cracked.So check that out to.
 
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